# Vintage Pine Electronics Amp with My Name On It!



## p_wats

*Vintage Pine Electronics Amp with My Name On It! - "Paul" 201 - Repair/Advice*

For the money, weight and tone I always thought my Blues Junior was the bees knees (or whatever the kids are saying these days). Then my world was rocked when I stumbled across a vintage tube amp made by Pine Electronics in Montreal around 1965. I got it on Ebay pretty much as a joke, as it was only $100 and the model is "Paul," so the amp literally has my name on it!

I guestimate this little guy to be about 5-8 watts, 3 tubes, 3 inputs and two knobs (volume and tone). It's light as a feather (easily half the weight of the Blues Junior, but about the same size) and the strange cabinet decor has a really distinctive look. Of course, none of that would matter if this thing didn't sound FRIGGIN' GREAT! 

I stood with it and my Blues Junior on either side and went back and forth with an a/b pedal for hours--I finally understand that "boxy" criticism everyone levels on the Blues Junior, as this amp is the exact opposite--rich, full and smooth. Compared to this the Fender sounds like I'm playing through a walky-talky.

It hums like a vending machine and gets louder depending on which lights in the apartment are on, but my god the tone (what's that thing you guys are always talking about...mojo? Heh)! Actually, used with the Mosfet Boost I built last year for no reason (and never thought I'd use) this amp is capable of some very rich and naturally distorted sounds. 

Here are some pics. I've got some maintenance questions below too for any of you with experience with old amps like this:










Here's the capacitor for the tone pot. I think I need to replace it, as the pot currently has no effect on the sound.


















Here she is with the serendipitously matching Mosfet Boost (build in a sewing machine pedal) and my old Saturn solid-body ('60s Japanese...plays great)!









What do you guys think about replacing the capacitors? I've read mixed things, but would it help reduce the hum/hiss? Also, this amp already has a 3-pronged cord, but should I do anything else to make sure it's safe? 

Whatever the case, I've found me new recording amp.


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## Hypno Toad

Can't give you much advice, but I can say I'm jealous. I'm not much into tube amps because of the price, but I love little vintage things like that.


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## p_wats

Hypno Toad said:


> Can't give you much advice, but I can say I'm jealous. I'm not much into tube amps because of the price, but I love little vintage things like that.


I was always worried about cheap old amps like this because I've had friends who received healthy electric shocks when using them, but this one has a 3-prong ground plug already, so I'm hoping it's not bad. It sounds phenomenal with that boost pedal.


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## bcmatt

Wow! It sounds like a great little amp you got there.

I wouldn't be afraid to replace that and all the capacitors. It may help with the noise (and effectiveness of the tone control). I guess it may alter the tone slightly as well. Come to think of it, those old carbon comp resistors probably add a bit of noise too but people often feel they also add a bit of the sweetness to the tone of old amps.

You could try replacing all the resistors with Carbon Films and the Caps with silver micas and polypropelene or something. Then if you think you hate the new sound, you could swap them back and you are only out a few bucks. Whatever, it's up to you and I'm sure there are some stronger opinions than mine.


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## John Bartley

My comments have to do with potential capacitor failure and proactive replacement. They aren't related to tone.

The photos you've shown us don't show anything other than ceramic disc caps. These aren't prone to failure like the old paper/foil caps are. The major trouble with the old paper/foil caps was that the paper would corrode away and the foil elements would short. In a tube amp with high levels of B+ voltage, a short circuit can cause some serious damage to tubes and transformers. In this case I'd leave the disc caps in place and I would only replace the filter caps in the power supply as well as any electrolytics used in cathode bias circuits. Also, I wouldn't suspect the cap in the tone circuit as much as I would suspect the control itself. A good cleaning might work, but before doing anything I'd check it with a DVM (or VTVM if you like vintage test gear :smile

and that's my two cents worth.

cheers

John

Edit :: that's just a really cool looking little amp! I think you're lucky to find something like that to play with, especially in such great shape. I keep my eyes open for them too, but I don't see too many like that.


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## jcayer

You might want to check this out:
http://www.jcayer.com/bricolages/renoamp.htm

I refurbished a Pine electro a couple of years back...


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## jcayer

Almost forgot,

Here's a fellow forumer's site,

http://sites.google.com/site/pepcotubeampinfo/

:smile:


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## p_wats

Thanks for the advice/links guys! It's all very helpful as I'm new to the world of vintage tube amps. Turns out a friend of mine had a similar "Paul" amp that he had a bunch of stuff done to and now doesn't like the sound, so I think I'll just start with the two electrolytic capacitors and see how that goes. I'm not even sure where I'd get a new can filter cap...any suggestions?


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## John Bartley

p_wats said:


> I'm not even sure where I'd get a new can filter cap...any suggestions?


You may not want to bother looking for a "can cap".

When I rebuild an old tube radio (similar to a tube amp in many ways), I decide if I want all the parts to look original or not. If I do, I gut the old cap can, put the new replacements inside the old can, extend the new cap leads out thru' the bottom, and use a solder type terminal strip under the chassis to make the connections on (instead of the lugs on the can). If I don't care about "under the chassis" appearance, then I put a pair of terminal strips under the chassis, mount new electrolytic filter caps on it, put the associated resistors and wires on the strips also, and leave the disconnected can on the top side just for appearance' sake.

The old cap can should have the values (uF and voltage) printed on the side.

cheers

John


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## keeperofthegood

p_wats said:


> Thanks for the advice/links guys! It's all very helpful as I'm new to the world of vintage tube amps. Turns out a friend of mine had a similar "Paul" amp that he had a bunch of stuff done to and now doesn't like the sound, so I think I'll just start with the two electrolytic capacitors and see how that goes. *I'm not even sure where I'd get a new can filter cap...any suggestions?*



http://www.justradios.com/orderform.html is where I would go. Email him to ask about something specific, I think he can get items too, seem to recall that from somewhere.


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## p_wats

Thanks guys! I spent the afternoon playing around with the amp and have found that the noise is only really an issue when the volume is past noon (ie, when it starts to break up). I've found that leaving the volume knob pretty low in conjunction with boost pedal gives me great volume with negligible noise (and much earlier breakup if I so choose...sweet tube distortion)! 

The tone control doesn't even bother me at all, as this thing sounds great as is. Any advice on how to use my multimeter to check if it's the cap or the pot? 

I think I'm going to use this amps tone as a guideline for some Blues Junior cap replacements!


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## BadCo73

*ARC Amp*

I have the same amp but the name on mine is ARC, I found mine in the local dump about 8 or 9 years ago. The cabinet looks to be covered with the same material as the one you have, but my cabinet was not in the best of shape so I got my brother to build me a new cabinet that I just varnished. I put a Celestion 10" greenback in it instead of the 8" inch speaker was in it when I found it, I also got him to make the cabinet just a little bit bigger to fit the 10" speaker. I love the sound of this little amp, it has very nice tone for what it is and I love how it sounds when it is cranked.


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## p_wats

BadCo73 said:


> I have the same amp but the name on mine is ARC, I found mine in the local dump about 8 or 9 years ago. The cabinet looks to be covered with the same material as the one you have, but my cabinet was not in the best of shape so I got my brother to build me a new cabinet that I just varnished. I put a Celestion 10" greenback in it instead of the 8" inch speaker was in it when I found it, I also got him to make the cabinet just a little bit bigger to fit the 10" speaker. I love the sound of this little amp, it has very nice tone for what it is and I love how it sounds when it is cranked.


The dump?! Wow! Nice find. My problem is that this one, while having an amazing tone, hums pretty loudly past 12 o'clock on the volume. I'm going to try some simple cap switches to see if that helps though. How about yours?


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## John Bartley

p_wats said:


> Any advice on how to use my multimeter to check if it's the cap or the pot?


Here's what I would do:

Disconnect any two wires from the pot. (note where they were, for correct rewiring)
Measure the resistance across the two outer lugs (not the centre one), and write this down.
Then measure the resistance from the centre lug to either of the outside lugs, and do this measuring by rotating the knob slowly through its full travel. It should go from zero ohms to almost the full amount measured in step #2.
Then measure from centre to the other outside lug. Other than being reversed, the resistances should be the same as in step #3.

If you get a smooth resistance increment in steps #3 and #4, and if the max resistance measured in #3 and #4 is the same as (or very close to) the resistance measured in step #2, then your pot is fine. This is where an analog meter is nice to have, as you can watch the travel of the needle and get a better idea visually about how smooth the resistance change is.

cheers

John


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## BadCo73

Mine is fairly quiet but when I turn the tone knob over to the bass side when it is cranked it makes quite a bit of noise but if I leave the tone knob in the middle it does not do it. I am no amp tech so I have done nothing about it I just leave the tone in the middle, but other than that I have had really no problems with it. Which is pretty good for as old as it is.


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## p_wats

Thanks for the pot advice, John! This one is wired a bit strangely, in the sense that there is only 1 wire going from the first lug (to the tone capacitor) and the second lug is grounded to the pot itself, leaving the third empty. I'm sure I can amend your advice to fit though.


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## p_wats

BadCo73 said:


> Mine is fairly quiet but when I turn the tone knob over to the bass side when it is cranked it makes quite a bit of noise but if I leave the tone knob in the middle it does not do it. I am no amp tech so I have done nothing about it I just leave the tone in the middle, but other than that I have had really no problems with it. Which is pretty good for as old as it is.


Hmm, that is interesting to know. My tone is fairly bass-y (sounds great, very full) at the moment and my tone pot doesn't work. Maybe it's stuck on the bass side of things?


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## John Bartley

p_wats said:


> the second lug is grounded to the pot itself



When one of the lugs is soldered to the case of the pot, that means that it is using the mechanical connection of the pot mounting to the chassis as an electrical connection also. Sometimes the mechanical connection develops some corrosion and the electrical connections "sees" a very high resistance. If your pot testing shows to be ok, then test for "zero" resistance between the grounded lug and somewhere else on the chassis. It should be zero. If it's anything else, then remove the pot, clean the mounting threads and hole, and remount it securely. A bit of white grease or Vaseline will keep air (oxygen) out of the electro-mechanical connection,and reduce the possibility of future corrosion (oxidation).

Let me know if you run into troubles.

cheers

John


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## keeperofthegood

p_wats said:


> Thanks for the pot advice, John! This one is wired a bit strangely, in the sense that there is only 1 wire going from the first lug (to the tone capacitor) and the second lug is grounded to the pot itself, leaving the third empty. I'm sure I can amend your advice to fit though.





p_wats said:


> Hmm, that is interesting to know. My tone is fairly bass-y (sounds great, very full) at the moment and my tone pot doesn't work. Maybe it's stuck on the bass side of things?



This makes sense and makes sense too why you have so much bass. What you have is a series RC circuit to ground, if either open then the circuit fails and you get all the treble there is, or if the wiper sticks (this can happen, you move the shaft but the shaft no longer moves the wiper) then you get a seemingly single setting that doesn't change, and if the capacitor shorts I think you get a volume control like effect (I think). 

The tone function of a series RC to ground filter is to bleed off treble, and if you have no treble then I am willing to bet between the grounded center lug and the outside lug of the pot to the capacitor is going to be 0 ohms or close to it, and if you just put the meter between that center and the outside lugs and turn the knob you wont have any resistance change.

EDIT: And, the ungrounded/unused lug is normal to see. Just not as normally done. It can act like a little antenna and broadcast signal causing noise. The better practice would be to wire that unused lug to the center lug.


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## p_wats

John Bartley said:


> If your pot testing shows to be ok, then test for "zero" resistance between the grounded lug and somewhere else on the chassis. It should be zero.


I tested the pot and it seems fine. Between lugs 1 and 3 I get a resistance of about 420K, then between lug 1 and 2 I get a range of 0-420 as it's turned. The ground lug also shows a resistance of zero when tested with another point on the chassis. 

Does that mean it's likely the ceramic capacitor? Lug 1 goes to the cap then to a lead on one of the tube sockets--could it be the tube? 

An amp tech friend of mine said bad tubes are the cause of nearly all the issues he sees and to check there. 



keeperofthegood said:


> EDIT: And, the ungrounded/unused lug is normal to see. Just not as normally done. It can act like a little antenna and broadcast signal causing noise. The better practice would be to wire that unused lug to the center lug.


That's a great point! I'll do that while I'm messing around with the guts.


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## keeperofthegood

p_wats said:


> I tested the pot and it seems fine. Between lugs 1 and 3 I get a resistance of about 420K, then between lug 1 and 2 I get a range of 0-420 as it's turned. The ground lug also shows a resistance of zero when tested with another point on the chassis.
> 
> Does that mean it's likely the ceramic capacitor? Lug 1 goes to the cap then to a lead on one of the tube sockets--could it be the tube?
> 
> An amp tech friend of mine said bad tubes are the cause of nearly all the issues he sees and to check there.
> 
> 
> 
> That's a great point! I'll do that while I'm messing around with the guts.



What is the tube line up? Ive been googling for a schematic with no luck but one site put the line up at 12AX7 50C5 and 35WA? I think they meant 35W4 but yea. From that, what tube, what pin number does the cap go to? if it is shorted (the cap) try just clipping the lead off at the pot (or desolder it) to take it out of the equation, how does that change the tone?


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## fraser

nice amp paul!

here is mine-











dont even know where i got it anymore- acquired in the early nineties somehow.
ive put an isolation transformer in it, but it doesnt sound good anymore- either a tube or other component is dying- kinda gives a weak, wobbly sound. ill look into it one day.

i do know that wild bill pointed me to a can cap replacement for this amp- available at 
http://thetubestore.com/ 
here in hamilton. ive been trying to get the link to it, but the webpage seems down at the moment-



> What is the tube line up? Ive been googling for a schematic with no luck but one site put the line up at 12AX7 50C5 and 35WA? I think they meant 35W4 but yea.


keeper, if pauls amp is indeed the same as mine, a model 201, then its a 50l6 and a 35z5. unless of course, ive got the wrong tubes in it lol.


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## keeperofthegood

kqoct I read the page wrong: http://www.fenderbronco.com/id14.html edit: Maybe, it does say the Paul is an 801 Chassis :/


Could be a tube too. Only way to know is grabbing a new one off somewhere. There is a pair of "suspicious" 50L6's on eBay at the moment for 1 dollar, and I think 5 in shipping. I say suspicious because the base and pins look rather dirty but for a buck eh  OH and 50L6 is the same as 6L6 12L6 25L6 and 35L6 just a higher voltage for the filament.


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## fraser

keeperofthegood said:


> kqoct I read the page wrong: http://www.fenderbronco.com/id14.html edit: Maybe, it does say the Paul is an 801 Chassis :/
> 
> 
> Could be a tube too. Only way to know is grabbing a new one off somewhere. There is a pair of "suspicious" 50L6's on eBay at the moment for 1 dollar, and I think 5 in shipping. I say suspicious because the base and pins look rather dirty but for a buck eh  OH and 50L6 is the same as 6L6 12L6 25L6 and 35L6 just a higher voltage for the filament.


hi keeper- thanks muchly for that info-
its entirely possible that i am using the wrong tubes. the originals for my paul amp were lost, and the sticker that is on the cabinet is mostly gone- 
ive got a regal #301 (canadian made too), and it is such a similar amp, that i used the same tubes it uses. 
in fact the very same tubes- ive only got one each of the 50l6 and 35z5 lol.
and both amps dont sound right anymore- these are ancient hit-ray tubes lol.
the tube store has them, one of these days ill get some fresh ones.

p_wats- id be really interested to know what tubes yours has in it, if it is a model 201, and if your sticker is intact and legible-


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## p_wats

Hey Fraser! Thanks for chiming in! Glad to see another "Paul" owner out there, even if yours isn't doing se well these days.




keeperofthegood said:


> kqoct I read the page wrong:
> Could be a tube too. Only way to ...un, as I don't know anything about tube amps!


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## keeperofthegood

fraser said:


> hi keeper- thanks muchly for that info-
> its entirely possible that i am using the wrong tubes. the originals for my paul amp were lost, and the sticker that is on the cabinet is mostly gone-
> ive got a regal #301 (canadian made too), and it is such a similar amp, that i used the same tubes it uses.
> in fact the very same tubes- ive only got one each of the 50l6 and 35z5 lol.
> and both amps dont sound right anymore- these are ancient hit-ray tubes lol.
> the tube store has them, one of these days ill get some fresh ones.
> 
> *p_wats- id be really interested to know what tubes yours has in it, if it is a model 201, and if your sticker is intact and legible-*


kqoct yes, there is a LOT of old metal out there with little or no documentation on it. And it seems the Canadian made anything (doesn't matter it was) is amongst the poorest documented of anything globally (I've seen obscure third world radios with better documentation than some leading Canadian made ones). I think as a nation we really do embody the saying "instructions? we don't need no loose leaf instructions."

Yes, if the information for the amp is still there, a photo/scan online would be good to add to the body of knowledge on this amp.


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## p_wats

Your wish is my command!










It is indeed a combination of 12AX7, 50L6 and 35Z5. I'm trying to track some new ones down as we speak!


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## fraser

keeperofthegood said:


> kqoct yes, there is a LOT of old metal out there with little or no documentation on it. And it seems the Canadian made anything (doesn't matter it was) is amongst the poorest documented of anything globally (I've seen obscure third world radios with better documentation than some leading Canadian made ones). I think as a nation we really do embody the saying "instructions? we don't need no loose leaf instructions."
> 
> Yes, if the information for the amp is still there, a photo/scan online would be good to add to the body of knowledge on this amp.


a few years ago, i saw the identical amp in a burlington music store- i immediately tried to look inside, but was stopped by an employee. when i explained i just wanted to see the sticker, he said the amp was $400. as my jaw dropped, he qualified the price with "hey, its from the 60's"
i was so flustered i never got to look inside to see the sticker lol.


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## fraser

p_wats said:


> Your wish is my command!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It is indeed a combination of 12AX7, 50L6 and 35Z5. I'm trying to track some new ones down as we speak!


stellar! thank you paul!


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## keeperofthegood

:wave: Thanks!!

Ok, what is here is:

35Z5/35Z5G/35Z5GT, Half-Wave Rectifier
Subs also: CV567 and CV568
http://www.nj7p.org/Tube4.php?tube=35Z5G

50L6/50L6-GT, Beam Power Amplifier
Subs also: CV2534 and CV571
http://www.nj7p.org/Tube4.php?tube=50l6

12AX7, High-Mu Twin Triode
More Subs than you can shake a stick at 
http://www.nj7p.org/Tube4.php?tube=12ax7

Now, usually the order would be Rectifier -> twin triode -> power tube, but in yours it looks the other way around. The capacitor looks like it connects to pin 8 of the 50L6?


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## BadCo73

Inside the cabinet of mine which I still have had a tag on the bottom of the cabinet with the chassis number and the tube layout, it is chassis #801 and the tubes are 35W4, 50C5 and 12AX7. If I remember correctly on my chassis beside each tube on the chassis it is stamped with the tube number right by the tube sockets. The amps pictured have different knobs than mine but other than that they are identical to the one I have.


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## p_wats

keeperofthegood said:


> What is the tube line up? Ive been googling for a schematic with no luck but one site put the line up at 12AX7 50C5 and 35WA? I think they meant 35W4 but yea. From that, what tube, what pin number does the cap go to? if it is shorted (the cap) try just clipping the lead off at the pot (or desolder it) to take it out of the equation, how does that change the tone?


Alright, so I just desoldered the cap from the tube socket (the only place the tone pot/cap combo was attached to the circuit) and it had no effect on the sound whatsoever. 

The cap is usually connected to the 50L6 at pin 8. Here's a pic:










I suppose, seeing as my multimeter showed the pot to be working and removing the cap had no effect on tone, I have no other recourse but to assume it has to be the capacitor? Or that the 50L6 is bad? 

Can anyone think of other options? It's going to take me some time to get new tubes and new caps, so this will have to be an ongoing project.


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## keeperofthegood

Well, that is the Cathode of the 50L6, where else does that go? It should, in theory, go either directly to ground or to a resistor to ground or a resistor/capacitor to ground. It looks like there is a green wire leading from it to somewhere. Follow that, if it goes to a resistor or resistor/capacitor, those should also be tested.

As the amp is working, would think the tubes are, for now, good.


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## keeperofthegood

BadCo73 said:


> Inside the cabinet of mine which I still have had a tag on the bottom of the cabinet with the chassis number and the tube layout, it is chassis #801 and the tubes are 35W4, 50C5 and 12AX7. If I remember correctly on my chassis beside each tube on the chassis it is stamped with the tube number right by the tube sockets. The amps pictured have different knobs than mine but other than that they are identical to the one I have.



So your compliment is:

35W4, Half-Wave Rectifier
http://www.nj7p.org/Tube4.php?tube=35w4

50C5, Beam Power Amplifier
http://www.nj7p.org/Tube4.php?tube=50C5

12AX7, High-Mu Twin Triode
More Subs than you can shake a stick at 
http://www.nj7p.org/Tube4.php?tube=12ax7

These are all miniature tubes, two 7 pin and one 9 pin. The other amps compliment was Octal and 9 pin miniature. Octals have been on their way out since the end of WW2 but guitar amps tended to keep them alive more. 

The 50C5, 35W4 group and the 35Z5, 50L6 group were very commonly found tubes in AA5 radios. The odd one in both amps is the 12AX7, very little mention of those in reference to radio.

Interesting comparative video:

[YOUTUBE]<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/YbFQlGJvgYI&hl=en_US&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/YbFQlGJvgYI&hl=en_US&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>[/YOUTUBE]


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## p_wats

keeperofthegood said:


> Well, that is the Cathode of the 50L6, where else does that go? It should, in theory, go either directly to ground or to a resistor to ground or a resistor/capacitor to ground. It looks like there is a green wire leading from it to somewhere. Follow that, if it goes to a resistor or resistor/capacitor, those should also be tested.
> 
> As the amp is working, would think the tubes are, for now, good.


It goes to a 150 Ohm resistor and then...if I'm following it right, to a 270K resistor & 0.047uf cap combo to ground. I've been looking for a schematic, but can't find anything. 

I assume those 2 yellow caps on the left are axial electrolytics that I might want to replace?


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## keeperofthegood

p_wats said:


> It goes to a 150 Ohm resistor and then...if I'm following it right, to a 270K resistor & 0.047uf cap combo to ground. I've been looking for a schematic, but can't find anything.
> 
> I assume those 2 yellow caps on the left are axial electrolytics that I might want to replace?



Those caps look like polyester films in the photo, sure fire way is if they have - or + or + and - markings then yes they are electrolytic, and cathode bypass ones seem to be often electrolytic and yes, they are probably due for updating. Cut one end, and put the replacements under them so it stays looking original  

. If you hand draw a tube, and put in the components from the cathode down does it in a way look like this:











See this big article http://mysite.du.edu/~etuttle/electron/elect27.htm


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## p_wats

keeperofthegood said:


> Those caps look like polyester films in the photo, sure fire way is if they have - or + or + and - markings then yes they are electrolytic, and cathode bypass ones seem to be often. If you hand draw a tube, and put in the components from the cathode down does it in a way look like this:


You're right about the caps, someone in another forum just confirmed they are polyester films. I'll leave them alone. 

As for your question/image, I'm not so sure I follow (I'm very new to tubes...VERY new). Sorry for my ignorance!

Incidentally, I tried wiring the tone cap up to another pot, just to further rule out the pot as the source of the problems and it still didn't work. I'm not that bothered by the lack of tone pot, as it sounds amazing without, but I would like to fix it for posterity's sake.


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## keeperofthegood

p_wats said:


> You're right about the caps, someone in another forum just confirmed they are polyester films. I'll leave them alone.
> 
> As for your question/image, I'm not so sure I follow (I'm very new to tubes...VERY new). Sorry for my ignorance!
> 
> Incidentally, I tried wiring the tone cap up to another pot, just to further rule out the pot as the source of the problems and it still didn't work. I'm not that bothered by the lack of tone pot, as it sounds amazing without, but I would like to fix it for posterity's sake.



:rockon2: I am not "new" but I am just really starting to learn this too. I think you missed my link I edited in. However, yea, time to sit down with a pencil and make a full end-to-end drawing of the amp schematic!!

If there is 2 resistors coming from Pin 8 of the 50L6, and the output transformer is connected to the middle of those two resistors, it is a "bootstrap" amp, the benefit of which is that your output transformer is referenced to ground and not B+ while keeping everything else the same. Probably a safety measure with this amp being line wired.


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## p_wats

keeperofthegood said:


> If there is 2 resistors coming from Pin 8 of the 50L6, and the output transformer is connected to the middle of those two resistors, it is a "bootstrap" amp, the benefit of which is that your output transformer is referenced to ground and not B+ while keeping everything else the same. Probably a safety measure with this amp being line wired.


Hmm, it looks like one of the wires from the transformer goes to the can cap, which then goes to the middle of those resistors, does that sound right? The other transformer wire goes directly to pin 3 of the 50L6.


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## keeperofthegood

p_wats said:


> Hmm, it looks like one of the wires from the transformer goes to the can cap, which then goes to the middle of those resistors, does that sound right? The other transformer wire goes directly to pin 3 of the 50L6.



It could. Draw out the schematics  and we will see it realised. I think part of the trouble is, this is more what people are accustomed to seeing in terms of amp layouts:










Here, it may look more like this in fact:


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## p_wats

Drawing out the schematics would be very good practice for me, but I fear it would take years, as I've never done that before. I'll definitely give it a shot as I get more knowledgeable. I think I'll take it to a tech in my neighbourhood to get an opinion. 

In the meantime, I need to get a multimeter that measures capacitance, so I can check that tone cap.


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## keeperofthegood

p_wats said:


> Drawing out the schematics would be very good practice for me, but I fear it would take years, as I've never done that before. I'll definitely give it a shot as I get more knowledgeable. I think I'll take it to a tech in my neighbourhood to get an opinion.
> 
> In the meantime, I need to get a multimeter that measures capacitance, so I can check that tone cap.


If you can do it in pencil on paper and photo that to me in PM's I could use a program or two I have handy to do it up neat and clean. Yes, it is good practice and any part you are stuck on just photo that and we can work past that too  

To me this is relaxing and fun, and I have been looking at amp schematics a LOT the last few months so educational to me too.

OH and you can try putting in a new tone cap inplace of the one you have now to see if that changes things. It currently is a 0.02uF buy the look of it, any from .047uF to .001uF would probably do you.


----------



## p_wats

keeperofthegood said:


> OH and you can try putting in a new tone cap inplace of the one you have now to see if that changes things. It currently is a 0.02uF buy the look of it, any from .047uF to .001uF would probably do you.


Hmm, how about voltage? the 2 yellow caps are 200v, but I don't see markings on the ceramics.


----------



## keeperofthegood

p_wats said:


> Hmm, how about voltage? the 2 yellow caps are 200v, but I don't see markings on the ceramics.


Safe bet is twice the supply voltage (and that is very often how electrolytics are done, so 117V supply, 240V caps for example).

Ceramic caps are usually done more though, 3 or 4 times supply. Standard voltages being what they are, I would look in the range 400 to 600 volts on those. In reading over a lot of schematics that is how many engineers have done those voltages too.

The ones you know the voltage of, may as well leave them that way


----------



## p_wats

keeperofthegood said:


> Safe bet is twice the supply voltage (and that is very often how electrolytics are done, so 117V supply, 240V caps for example).
> 
> Ceramic caps are usually done more though, 3 or 4 times supply. Standard voltages being what they are, I would look in the range 400 to 600 volts on those. In reading over a lot of schematics that is how many engineers have done those voltages too.


Wonderful! Thanks. I don't have anything that large at the moment, so I'll grab one soon. 

People have been saying that I should put an isolation transformer in this. Think it's necessary?


----------



## keeperofthegood

p_wats said:


> Wonderful! Thanks. I don't have anything that large at the moment, so I'll grab one soon.
> 
> People have been saying that I should put an isolation transformer in this. Think it's necessary?


I've not seen the other side, if the line goes to a power amp then to the rest of the circuit no, if the line wires go directly into the tubes then yes.

There are a bunch on eBay ranging from 1 dollar to 1000000s and shipping as wild to match


----------



## p_wats

Hmm, when you say "power amp" what should I be looking for? Basically, what you see in the gut shot is all there is. The only wire on the other side connects the transformer directly to pin 3 of the 50L6.

That said, I just spoke to Tim at Superfuzz in Toronto (formerly of Songbird) and he said it would be overkill to install an isolation transformer and that the 3-prong chord could be doing more harm than good (as it's grounded straight to the chassis). 

That threw me for a loop. I basically just want to be able to record with this amp and maybe play it at small gigs safely (don't often play with drums). 

He also said replacing the filter cap would probably not have much effect on the noise, as these are noisy old amps anyway.


----------



## keeperofthegood

XD so the chassis is wired hot. Isolate it. Over kill or not, it is safer. There is a reason the UL/CSA made rules against these.

You can get a decent isolation transformer for 40 bucks from eBay (there was a site selling the *ONEAC CL 1101 5* for 9.95 but I have not been able to refind it sadly, that one is a 1.5A isolation transformer and what I use).

Yes, there will be noise. There are ways you can remove that noise a lot and they involve a few parts additions. Will it ever be "noise free" hmm, probably not without changing more than what you would want changed. Certainly I don't think it is out of the ballpark to clean it up some though (like grounding that pot lug etc).


----------



## p_wats

keeperofthegood said:


> You can get a decent isolation transformer for 40 bucks from eBay (there was a site selling the *ONEAC CL 1101 5* for 9.95 but I have not been able to refind it sadly, that one is a 1.5A isolation transformer and what I use).


Like this one? Doesn't look like what I was expecting...

http://cgi.ebay.ca/Oneac-CL1101-Pow...lectrical_Equipment_Tools?hash=item2557db8039

I could always buy one and then take it to a tech to install...or is it a simple process?

As for noise, I actually don't mind the noise, as I can reign it in with the Mosfet Boost and it sounds amazing. I've found the tubes at thetubestore.com and will probably order replacements just in case. 

Basically, my main goal is just that tone pot at the moment, but I don't have a new cap to try there.


----------



## keeperofthegood

p_wats said:


> Like this one? Doesn't look like what I was expecting...
> 
> http://cgi.ebay.ca/Oneac-CL1101-Pow...lectrical_Equipment_Tools?hash=item2557db8039
> 
> I could always buy one and then take it to a tech to install...or is it a simple process?
> 
> As for noise, I actually don't mind the noise, as I can reign it in with the Mosfet Boost and it sounds amazing. I've found the tubes at thetubestore.com and will probably order replacements just in case.
> 
> Basically, my main goal is just that tone pot at the moment, but I don't have a new cap to try there.



Close enough  That model is 1.0 amps, mine is 1.5 amps. Your tube heaters are using 0.15amps and the most the tube plates would draw is 0.06 amps (from the data sheets). So no worries. And, no installation. you plug the one end of the ONEAC into the wall, and then the amp plugs into the ONEAC and you are done 

For that tone cap, still, try drawing out the way it is wired. Like I said, I can help with that easy enough. Good practice for me too.


----------



## greco

This is also an isolation transformer by Hammond. Problem is that it is expensive !! 

http://datasheet.octopart.com/171A-Hammond-datasheet-23660.pdf

You can also put 2 transformers together (Transformer 1 secondary to Transformer 2 secondary) IF you have 2 of the same transformers and end up with the VA (watts) you require for your amp. There is an old thread about this.

*Keeps*...Is a power conditioner the same as an isolation transformer? I always thought that a power conditioner just filtered/"stabilized" the input VAC form the wall. Thanks 

Cheers

Dave


----------



## p_wats

keeperofthegood said:


> Close enough  That model is 1.0 amps, mine is 1.5 amps. Your tube heaters are using 0.15amps and the most the tube plates would draw is 0.06 amps (from the data sheets). So no worries. And, no installation. you plug the one end of the ONEAC into the wall, and then the amp plugs into the ONEAC and you are done
> 
> For that tone cap, still, try drawing out the way it is wired. Like I said, I can help with that easy enough. Good practice for me too.


Really? So all I do is buy that, plug the amp cord in there and the ONEAC to the wall, then I'm safe to gig with this little guy? If so I'll buy it right now! Ha. 

I'll give the drawing a shot when I have some down time, meanwhile I've asked justradios if they've got the schematic. 

Thanks again for all your help!


----------



## Wild Bill

p_wats said:


> Like this one? Doesn't look like what I was expecting...
> 
> http://cgi.ebay.ca/Oneac-CL1101-Pow...lectrical_Equipment_Tools?hash=item2557db8039
> 
> I could always buy one and then take it to a tech to install...or is it a simple process?
> 
> 
> Basically, my main goal is just that tone pot at the moment, but I don't have a new cap to try there.


Nope! WAY overkill! Zillion dollar part for a 50 cent application.

An isolation transformer looks like any other transformer. It is designed to be bolted onto the chassis. You would need one that has a 120 volt primary and a 120 volt secondary. For a current or VA rating you add up all the watts involved. A 50L6 has a 50 volt filament that draws .15 amps so there's 7.5 watts. All your tubes will add up to a bit over 15 watts and the amp puts out maybe 2. This is just a little bit over the rating for a Hammond 169PS isolation transformer. Hammond makes RUGGED trannies so I would go with this one rather than the bigger and more expensive 169QS, which would be far over-rated.

Incidently, I don't mean to keep picking on Keeps with his advice but he had mentioned that *"Safe bet is twice the supply voltage (and that is very often how electrolytics are done, so 117V supply, 240V caps for example)."* This is not really true!

First off, what is the supply voltage? Just because the amp plugs into the wall doesn't mean that the caps are supplied with 120volts. That line voltage is rectified in your amp by a half-wave rectifier, the 35Z5. Your caps are never gonna see much more than 90 volts. That also depends on where they are in the circuit. In some positions they won't see any volts at all!

As for filters, please don't use "double" as a rule of thumb. Most amps have a power transformer that steps up the voltage to make a high voltage for the tube plates. You could have more than 500 volts of DC generated by the power supply and filtered by those capacitors. At only double the line voltage of 120 volts they would blow!

In your amp you will likely find that, as said already, there is no power transformer and only a halfwave rectifier the manufacturer used 150 volt rated caps, the closest higher standard rating offered in stores.

Me, I wouldn't bother with an isolation transformer. Zillions of amps, radios and tvs were made in the Golden Years without one and people were NOT dying like flies from electrocution! I would just make sure that the hum bypass cap tied to one or the other of the 120 volt lines coming into the amp is in good shape. It might be a good idea to replace it with something way over-rated, like a 600 volt Orange Drop.

When overhauling an old amp and trying to fix problems it can help to know the "usual" stuff! Usually, filter caps get old and dry up, causing loud power supply hum. Other caps DON'T! They work forever unless some failure blows them up. Ceramics are the most reliable of all. So one of these caps failing can cause a problem but it is not the most common.

Resistors, especially power resistors, are likely culprits. The really old amps using those old carbon comp resistors have the most resistor failures, since those old style resistors were really crappy quality.

The number one fault is always tubes! They are like tires and windshield wiper blades. They're supposed to wear out! If you don't have a tube tester you can always use a known good tube to sub in as a test.

I'd hate to see you replace every single part in your amp trying to fix any problems. This is a very expensive way to fix something and besides, you won't learn anything. Hopefully, you wouldn't use the same approach to fix a car engine.

This link is one of the best anywhere for working on tube amps:

http://www.geofex.com/

In the top left of the opening page you'll see "Tube Amp De-bugging Page". Even experienced techs refer to this site often.

There were a lot of amps like yours made back in those days. Many were sold by stores like Sears as a "first" amp to go with a "first" guitar. In Canada Pine was one of their sources and so was Garnet Amps. The circuit is basically a Fender Champ, perhaps the simplest amp you can make. You have only one output tube, one preamp tube and a rectifier for the power supply.

To keep costs down the manufacturer used the cheapest parts he could get. Resistors and caps are all pretty much the same but you could consider a better output transformer. The biggest improvement would probably be a modern speaker. An Eminence would likely sound killer and twice as loud!

:food-smiley-004:


----------



## greco

p_wats said:


> Really? So all I do is buy that, plug the amp cord in there and the ONEAC to the wall, *then I'm safe to gig with this little guy? *If so I'll buy it right now! Ha.


That is my question...Is a *power conditioner *going to provide you with the safety you require?

Dave


----------



## p_wats

Wild Bill said:


> Nope! WAY overkill! Zillion dollar part for a 50 cent application.


*Wild Bill*! I've been reading your posts all over for the past 2 days trying to get more info before I acted on anything. 

So far here is where my head is at: the amp sounds amazing right now. A bit of hum, but it's not a deal-breaker. I'd rather not change anything but the tubes if I can avoid it. However:

1) *The tone control doesn't work* (not a big deal, as it sounds great right now, but I want to fix it for my pride). I've ruled out the pot and removing it from the circuit altogether has no effect on tone, so aside from the ceramic cap being dead I'm stumped.

2) *Safety*: I just want to be able to play small gigs with this little guy and not worry. 



Wild Bill said:


> I would just make sure that the hum bypass cap tied to one or the other of the 120 volt lines coming into the amp is in good shape. It might be a good idea to replace it with something way over-rated, like a 600 volt Orange Drop.


Hmm, which cap would that be given the gut shot I posted? Aside from the tone cap and filter can there are 2 200v 0.047 polyester film caps and 2 ceramics.

As for resistors, I checked all their values last night and they seem fine.


----------



## keeperofthegood

greco said:


> This is also an isolation transformer by Hammond. Problem is that it is expensive !!
> 
> http://datasheet.octopart.com/171A-Hammond-datasheet-23660.pdf
> 
> You can also put 2 transformers together (Transformer 1 secondary to Transformer 2 secondary) IF you have 2 of the same transformers and end up with the VA (watts) you require for your amp. There is an old thread about this.
> 
> *Keeps*...Is a power conditioner the same as an isolation transformer? I always thought that a power conditioner just filtered/"stabilized" the input VAC form the wall. Thanks
> 
> Cheers
> 
> Dave


In this case, it is isolation for sure. They use an iron type in the transformer that does not promote spurious signals. At least that is what the tech doc on them claims.




p_wats said:


> Really? *So all I do is buy that, plug the amp cord in there and the ONEAC to the wall, then I'm safe to gig with this little guy? If so I'll buy it right now! Ha. *
> 
> I'll give the drawing a shot when I have some down time, meanwhile I've asked justradios if they've got the schematic.
> 
> Thanks again for all your help!


Yup, and that is the reason I recommended this one, there is no installation and can be used for other applications over time you are not dedicating something to one job.



Wild Bill said:


> Nope! WAY overkill! Zillion dollar part for a 50 cent application.
> 
> An isolation transformer looks like any other transformer. It is designed to be bolted onto the chassis. You would need one that has a 120 volt primary and a 120 volt secondary. For a current or VA rating you add up all the watts involved. A 50L6 has a 50 volt filament that draws .15 amps so there's 7.5 watts. All your tubes will add up to a bit over 15 watts and the amp puts out maybe 2. This is just a little bit over the rating for a Hammond 169PS isolation transformer. Hammond makes RUGGED trannies so I would go with this one rather than the bigger and more expensive 169QS, which would be far over-rated.
> 
> Incidently, I don't mean to keep picking on Keeps with his advice but he had mentioned that *"Safe bet is twice the supply voltage (and that is very often how electrolytics are done, so 117V supply, 240V caps for example)."* This is not really true!
> 
> First off, what is the supply voltage? Just because the amp plugs into the wall doesn't mean that the caps are supplied with 120volts. That line voltage is rectified in your amp by a half-wave rectifier, the 35Z5. Your caps are never gonna see much more than 90 volts. That also depends on where they are in the circuit. In some positions they won't see any volts at all!
> 
> As for filters, please don't use "double" as a rule of thumb. Most amps have a power transformer that steps up the voltage to make a high voltage for the tube plates. You could have more than 500 volts of DC generated by the power supply and filtered by those capacitors. At only double the line voltage of 120 volts they would blow!
> 
> In your amp you will likely find that, as said already, there is no power transformer and only a halfwave rectifier the manufacturer used 150 volt rated caps, the closest higher standard rating offered in stores.
> 
> Me, I wouldn't bother with an isolation transformer. Zillions of amps, radios and tvs were made in the Golden Years without one and people were NOT dying like flies from electrocution! I would just make sure that the hum bypass cap tied to one or the other of the 120 volt lines coming into the amp is in good shape. It might be a good idea to replace it with something way over-rated, like a 600 volt Orange Drop.
> 
> When overhauling an old amp and trying to fix problems it can help to know the "usual" stuff! Usually, filter caps get old and dry up, causing loud power supply hum. Other caps DON'T! They work forever unless some failure blows them up. Ceramics are the most reliable of all. So one of these caps failing can cause a problem but it is not the most common.
> 
> Resistors, especially power resistors, are likely culprits. The really old amps using those old carbon comp resistors have the most resistor failures, since those old style resistors were really crappy quality.
> 
> The number one fault is always tubes! They are like tires and windshield wiper blades. They're supposed to wear out! If you don't have a tube tester you can always use a known good tube to sub in as a test.
> 
> I'd hate to see you replace every single part in your amp trying to fix any problems. This is a very expensive way to fix something and besides, you won't learn anything. Hopefully, you wouldn't use the same approach to fix a car engine.
> 
> This link is one of the best anywhere for working on tube amps:
> 
> http://www.geofex.com/
> 
> In the top left of the opening page you'll see "Tube Amp De-bugging Page". Even experienced techs refer to this site often.
> 
> There were a lot of amps like yours made back in those days. Many were sold by stores like Sears as a "first" amp to go with a "first" guitar. In Canada Pine was one of their sources and so was Garnet Amps. The circuit is basically a Fender Champ, perhaps the simplest amp you can make. You have only one output tube, one preamp tube and a rectifier for the power supply.
> 
> To keep costs down the manufacturer used the cheapest parts he could get. Resistors and caps are all pretty much the same but you could consider a better output transformer. The biggest improvement would probably be a modern speaker. An Eminence would likely sound killer and twice as loud!
> 
> :food-smiley-004:


kqoct Sorry, I should have spoken clearer. The line voltage is ~120, I was ignoring the rectified value because it would be ~120 if the tube shorted out. :/ no idea when I learned that, to use the raw voltage, not the modified. 

For the ceramics (yea, I think he has a resistor gone more than that cap but hey stranger things have happened too LOL) there are power on spikes and there are spikes that can come from plugging the instrument in and out. This would be the only reason why I see "plate volts +275" down to "plate volts +104" and the cap from there rated 600v or more, that some extra padding is included in those cap voltage values.

... then again, it could be a matter of "unmodified" voltage too.


----------



## Wild Bill

keeperofthegood said:


> Yup, and that is the reason I recommended this one, there is no installation and can be used for other applications over time you are not dedicating something to one job.


I didn't think of that! It's a very good point.

I don't think that it will help with noise much, though. I doubt if the amp is picking up line noise. More likely if there is a scratchy noise (other that from turning a dirty control, of course) it's from a resistor breaking down, a cap leaking or even a cheap OT that has had its internal insulation deteriorate over the years.

Paul, I can't tell you which cap to replace 'cuz I can't follow the wiring with those damn pictures! I REALLY HATE trying to diagnose with pictures! You can never see what you need to see.

Give me a schematic any day! The cap would be obvious! Just follow the white and black wires from the power cord. One side will go through a switch on the pot, maybe the fuse holder and on to the tube rectifier. The other should be tied to a common ground point for the circuit, but that ground point should NOT be tied to the chassis! All the grounds should come together and then there will be a big cap from that point to ground. That's the cap to check.

:food-smiley-004:


----------



## p_wats

Wild Bill said:


> I don't think that it will help with noise much, though. I doubt if the amp is picking up line noise. More likely if there is a scratchy noise (other that from turning a dirty control, of course) it's from a resistor breaking down, a cap leaking or even a cheap OT that has had its internal insulation deteriorate over the years.
> 
> Paul, I can't tell you which cap to replace 'cuz I can't follow the wiring with those damn pictures! I REALLY HATE trying to diagnose with pictures! You can never see what you need to see.
> 
> Give me a schematic any day! The cap would be obvious! Just follow the white and black wires from the power cord. One side will go through a switch on the pot, maybe the fuse holder and on to the tube rectifier. The other should be tied to a common ground point for the circuit, but that ground point should NOT be tied to the chassis! All the grounds should come together and then there will be a big cap from that point to ground. That's the cap to check.
> 
> :food-smiley-004:


Yeah, the pictures are a bit messy and hard to tell what goes where. I'm looking for a schematic, and and worst will try to figure one out with Keeperofthegood's help. 

The isolation transformer idea is more for safety than noise. The noise doesn't really bother me. I just want it to be safe to play small shows with. Actually installing an isolation transformer is something I'm not yet knowledgeable enough to try, so if that Ebay product will work and make it safer then I'll do it. If it's not a safety concern as is then I won't bother. Thoughts?

As for following the wires, I have what is likely some disappointing news: 

The *white wire* from the cord goes to the power switch.
The *black wire* goes to the fuse
The *green wire* goes directly to the chassis. 

Is it possible that someone removed the big cap when they added the 3-prong chord (which I assume isn't original)? 

Eventually I'm going to have someone in Toronto actually look at the amp, but I'm trying to learn as much as I can. Ideally I'm going to look for a tech who might be willing to let me "sit in" while they give it a once over, so I can learn something.


----------



## p_wats

Alright, so I've been messing around with the tone capacitor and pot some more outside of the circuit. Here's what I've found: 

*Cap:* I don't have a way to measure the capacitance to make sure it's working, but I figured, why not gator clip it across the volume pot of another circuit to see if it affects the sound. Low and behold, it kills the treble completely.

I tried it clipped across the volume pot of this amp as well and it kills the treble (along with most of the hiss too). 

*Pot:* I hooked it up to another simple circuit I had kicking around and it worked perfectly. 

Therefore, I have no recourse but to say that both the cap and pot are fine. In my mind that only leaves a few options for the faulty tone control: 1) The 50L6 that the cap connects to is bad 2) The way the pot/cap are wired isn't working properly 3) Some other component that in some way affects the tone control isn't working.

I'll try to start drawing up a "schematic" (quotations as it probably won't look like a schematic to you guys...more like a drawing of where things are in my eyes).


----------



## keeperofthegood

p_wats said:


> Alright, so I've been messing around with the tone capacitor and pot some more outside of the circuit. Here's what I've found:
> 
> *Cap:* I don't have a way to measure the capacitance to make sure it's working, but I figured, why not gator clip it across the volume pot of another circuit to see if it affects the sound. Low and behold, it kills the treble completely.
> 
> I tried it clipped across the volume pot of this amp as well and it kills the treble (along with most of the hiss too).
> 
> *Pot:* I hooked it up to another simple circuit I had kicking around and it worked perfectly.
> 
> Therefore, I have no recourse but to say that both the cap and pot are fine. In my mind that only leaves a few options for the faulty tone control: 1) The 50L6 that the cap connects to is bad 2) The way the pot/cap are wired isn't working properly 3) Some other component that in some way affects the tone control isn't working.
> 
> I'll try to start drawing up a "schematic" (quotations as it probably won't look like a schematic to you guys...more like a drawing of where things are in my eyes).


:wave: All drawings are good. I've seen some REALLY rough schematics. Like, when I do them  hehe before firing up one of the programs on the compy for drawing things out.

Use the two schematics I posted earlier too as a visual reference for "how" to draw out the parts too, that will help a lot.

Maybe a good pot cleaner is needed too?


----------



## p_wats

No drawing yet, but I did check all the resistors to see if they match their colour-coded values. Here are any variations I've found:

There are two 3.3K resistors that measure 3.5K and 3.6K respectively.

There are four 270K resistors that measure closer to 290K. 

One 150 Ohm resistor measures 190 Ohm.

Otherwise they are all pretty close to what they should be. I wouldn't think these differences are actually bad enough to merit replacement. Am I wrong?


----------



## keeperofthegood

p_wats said:


> No drawing yet, but I did check all the resistors to see if they match their colour-coded values. Here are any variations I've found:



Most of these resistors would be 5% or 10% Tolerances (silver or gold band, no band is 20%), so let me break what you found down in those terms and see where your measured values lay:



p_wats said:


> There are two 3.3K resistors that measure 3.5K and 3.6K respectively.


5% of 3300 = +/-165
10% of 3300 = +/-330
20% of 3300 = +/-660

This one measures only a little more than 5% less than 10%



p_wats said:


> There are four 270K resistors that measure closer to 290K.


5% of 290000 = +/-14500
10% of 290000 = +/-29000
20% of 290000 = +/-58000

This one measures a little more than 5% less than 10%



p_wats said:


> One 150 Ohm resistor measures 190 Ohm.


5% of 150 = +/-7.5
10% of 150 = +/-15
20% of 150 = +/-30

This one is over 20% greater than the marked value.



p_wats said:


> Otherwise they are all pretty close to what they should be. I wouldn't think these differences are actually bad enough to merit replacement. Am I wrong?


I will leave the "_change that resistor_" to others, however, it is measuring high and I will "wild guess" that that resistor is in a cathode leg, affecting tube bias etc etc etc.


----------



## p_wats

keeperofthegood said:


> 5% of 150 = +/-7.5
> 10% of 150 = +/-15
> 20% of 150 = +/-30
> 
> This one is over 20% greater than the marked value.
> 
> I will leave the "_change that resistor_" to others, however, it is measuring high and I will "wild guess" that that resistor is in a cathode leg, affecting tube bias etc etc etc.


Funny you should mention it, as that 150 Ohm resistor is connected to the same leg of the 50L6 socket that also connects to the tone cap. Think it could be the culprit of the lack of tonal adjustment?


----------



## keeperofthegood

p_wats said:


> Funny you should mention it, as that 150 Ohm resistor is connected to the same leg of the 50L6 socket that also connects to the tone cap. Think it could be the culprit of the lack of tonal adjustment?



:rockon2: Well, a 150 ohm resistor is less than a buck from Mouser. Why not? I mean, if it IS the culprit (could be for the noise at least, crystallized carbon is noisy) then hey, bob's yer uncle!!


EDIT ... erm, and 8 or 9 dollars shipping :/ I PM you ok!


----------



## keeperofthegood

:wave: BUMP!


Paul, how goes the schematic and the amp in general?


----------



## p_wats

Not much progress since last week, as I was out of town ringin' in the new year. I haven't been able to get to a parts store to buy any new resistors and am still waiting on 35z5 tubes. 

I'm hoping to start a rough schematic drawing very soon though (just working out some recent wrinkles in my employment...).


----------



## p_wats

Alright, so I was able to get some parts today. I immediately replaced the 150 Ohm resistor that seemed to have drifted beyond its tolerance. 

Unfortunately, this didn't bring the tone pot back to life, so it's back to the drawing board on that. However, would it be crazy to think replacing this resistor actually made the amp a little louder though? It might be my ears wanting to justify the effort, but it seems there's a tiny difference. 

The next step is to try new tubes when they are available. In the meantime I'll give a schematic a shot as soon as I've got some downtime. 

In other news, I went to Paul's Boutique in Kensington Market today and they knew of this amp right away (even though I didn't have it there to show them). They said it's a highly regarded amp that blows a Blues Junior or similar out of the water regardless of the inherent noise. Turns out they sell them for double what I got mine for on Ebay (when they can find one), so I'm happy. 

They'll also put in an isolation transformer and said it wouldn't cost much (which is the opposite of what I was told by another shop last week).


----------



## p_wats

Another quick update: looking at the guts of my amp it's obvious someone has been in there messing around before me (however added the 3-prong cord, for instance), so I started thinking that maybe other things have been changed too and looked up gut shuts online. 

Low and behold, I find an old post on this forum by none other than our own *Fraser* (who chimed in with a picture of his amp earlier in the thread) that has links to gut shots. 

If you look at his guts here:










And mine here:










You'll notice that the tone cap is wired to a different spot in each. His seems to cross over the 50L6 (the socket in the centre) and connect to the turret board at the bottom, whereas mine goes to the cathod of the socket. 

I used gator clips to try his way and it definitely has an effect on the tone, but only at the most extremes (ie, all the way to bass kills the treble and adds a huge amount of hiss, and a slight turn the opposite way brings back the treble (and less hiss) with pretty much no change throughout the rest of the pot. 

If Fraser would chime in with a closer gut shot that would be ideal.


----------



## John Bartley

p_wats said:


> You'll notice that the tone cap is wired to a different spot in each. His seems to cross over the 50L6 (the socket in the centre) and connect to the turret board at the bottom, whereas mine goes to the cathod of the socket.


A close up photo of Frazers amp would help, and while I didn't say anything, I did wonder whether yours had been molested in the past. I have never seen a tone control in the cathode circuit. I usually expect them to be in a grid or plate circuit. It would be nice if we could find a schematic. I've looked for one, but without success.

cheers

John


----------



## p_wats

John Bartley said:


> A close up photo of Frazers amp would help, and while I didn't say anything, I did wonder whether yours had been molested in the past. I have never seen a tone control in the cathode circuit. I usually expect them to be in a grid or plate circuit. It would be nice if we could find a schematic. I've looked for one, but without success.
> 
> cheers
> 
> John


Yeah, I found my tone wiring a bit weird too. I've since soldered it up according to the testing done after seeing Fraser's photo and it does adjust the tone (abrubtly, but still seems to do it). 

I'm going to try my hand at drawing a schematic based on my wiring, but it might not be the most accurate do to past meddling and my poor ability. 

In the end though, I really can't stress how great this amp sounds. Kills me every time.


----------



## fraser

just took a bunch of gut shots- probably overkill, but ill post em all here anyway- i just got home and am desperate for a shower before the game starts lol.
i think aside from my adding an isolation tranny and 3 prong cord, this amp is as new inside-


----------



## fraser




----------



## fraser

ill leave the back of the amp off, so if youve got any questions, i can look, or take another pic for ya!


----------



## p_wats

fraser said:


> just took a bunch of gut shots- probably overkill, but ill post em all here anyway- i just got home and am desperate for a shower before the game starts lol.
> i think aside from my adding an isolation tranny and 3 prong cord, this amp is as new inside-


Wow! Thanks for those pictures. 

There are definite discrepancies with mine. What changes in the wiring had to be made to get your extra transformer in there? It looks like we've got a few differences coming off the volume pot (one lug on the bottom looks like you've got 3 wires coming off it while I only have two). I also have two wires coming off a lug of the preamp tube whereas you only seem to have one (the blue-ish wire going to the lug on the volume pot I just mentioned).  Can you confirm these connections (I can take pictures if it's confusing)? 

Also, I guess the tone pot really is wired to the cathode! Weird how mine doesn't work there, but works (fairly well) going to the bottom turret.

Thanks again for the help! We're surely amassing some wealth for other "Paul" enthusiasts out there.


----------



## fraser

hi paul- the transformer hooks up to the fuse- (yellow wire at end of fuse holder) and to the green wire you see coming off the lug on the back of the volume pot- i just connected it to where the original cord went-

yup- the other lug on back of the volume pot has three wires coming off it- one of them goes to the front lug of the pot, another goes to the preamp tube, and another goes to that front terminal strip.

and nope- all lugs of the preamp tube only have one wire attached to each.

now keep in mind that mine doesnt actually work currently lol, tho i never changed anything other than the power wires, who knows?

strange beasts arent they?
hope this helps.


----------



## fraser

paul, i just tried my regal amp out, its really the same amp, and the tone knob essentially does nothing, except an either bassy tone all the way to the left, or a trebly tone anywhere else on the knob-


----------



## p_wats

fraser said:


> paul, i just tried my regal amp out, its really the same amp, and the tone knob essentially does nothing, except an either bassy tone all the way to the left, or a trebly tone anywhere else on the knob-


That's funny, as that's exactly what my tone pot does now in the position I switched it to thinking it was where yours was. As long as it's doing no damage I may just leave it there (but I'll probably as a tech I know). 

I'll try wiring the other differences like yours to see what results I get.


----------



## p_wats

Hey Fraser, I just tried wiring mine up like yours and it didn't work either. Maybe you should try yours like mine? I might just leave the tone pot out of the circuit altogether until I have time to draw up a schematic and see where it makes sense to be. 

How is the tone pot wired in your regal?


----------



## fraser

hi paul- the tone pot is wired the same on the regal- ill have to get some shots of that tonite, just on my way to work, but the regal is now working fine-:smile:
my paul does work, to a degree, except theres a "fluttering" to the sound- i think it needs a cap job or something-

edit- turns out its not wired the same!


----------



## fraser

heres some gut shots of my regal- its a model 300. essentially the same as the pine, component placement is a bit different, and the cabinet of slightly better construction- looks like it has an asbestos shield on the back cover lol-
its this amp here-


----------



## fraser




----------



## p_wats

Thanks for the photos! I'm not really knowledgeable enough to make heads or tales of those guts (or my amp's for that matter), but I'm sure that will be helpful to more experienced parties!

How does the Regal sound?


----------



## greco

Cool thread...thanks for all the pics.

Cheers

Dave


----------



## fraser

so my paul amp tone control has only one wire, with cap, connected to the tube socket- and the pots wiper is grounded to its case-
(the green wire coming off the volume pot in that earlier pic doesnt go to the tone pot- just noticed that pic may give that impression- it actually goes to the power-)
while my regal has the wiper, with cap connected to one tube socket, and the full open lug connected to the other tube socket. hmmm.
the regal tone pot definately works as i discribed before- im going to have to throw those tubes into the paul and see how the tone pot works-


----------



## fraser

p_wats said:


> Thanks for the photos! I'm not really knowledgeable enough to make heads or tales of those guts (or my amp's for that matter), but I'm sure that will be helpful to more experienced parties!
> 
> How does the Regal sound?


lol- i know about the same as you paul
the regal sounds good- bit of a hum of course, but nothing unnerving.
very warm tone, not very bright, almost zero headroom, it distorts at any volume really lol- i like that. cranking it doesnt introduce any more real breakup, it just increases the volume.
definately has a tube radio kinda sound- you know that warm quality, with a bit of a ratty edge.
ive never been good at putting tones into words, put im trying here, really.
it never really sings on its own- sustained notes dont 'bloom', almost like somethings holding it back, but its got loads of character.
with a germanium boost, and my strats tone control backed right off, it screams- lots of 'bloom' then lol.
very manageable volume, and earthy, gritty tone.
one cool advantage is the cab is big enough that even with a little speaker and low wattage it never sounds boxy-
ive got a couple other small modern tube amps that may have better tone all around, but they have a boxy quality to them-

its funny, a week or two ago i thought this amp needed work, only thing i did was pull the tubes out to confirm what they were back when this thread started- perhaps when i popped em back in they loosened some crud in there or something. sounds good now.


----------



## keeperofthegood

fraser said:


> so my paul amp tone control has only one wire, with cap, connected to the tube socket- and the pots wiper is grounded to its case-
> (the green wire coming off the volume pot in that earlier pic doesnt go to the tone pot- just noticed that pic may give that impression- it actually goes to the power-)
> while my regal has the wiper, with cap connected to one tube socket, and the full open lug connected to the other tube socket. hmmm.
> the regal tone pot definately works as i discribed before- im going to have to throw those tubes into the paul and see how the tone pot works-



What tube number? What socket pin number?


----------



## fraser

keeperofthegood said:


> What tube number? What socket pin number?


well.. i, ermmm 

ok lets discount my paul amp for the now- i must test it again- 
im already getting confused- on the regal- the tone connects from the wiper of the pot, to one of the outer lugs on the tube socket for the 35z5- its got 4 lugs on the outside of the socket, not on the pins- none of the other 3 lugs are connected to anything.
the outer lug of the tone pot, has the cap , and is connected to one of the pins on the 50l6
honestly, i dont know the correct names for any of this, so treat me as you would a 6 year old-
my journey into amplifier technology lasted about a week, and then i went back to making noise lol.


----------



## keeperofthegood

fraser said:


> well.. i, ermmm


kkjuw I know, all the tough questions!



Looking at the socket from the bottom, from either the key-way (on octals) or the space (9 and 7 pin tubes) the first pin on the left is 1, and you go clock-wise around from there


----------



## fraser

keeperofthegood said:


> kkjuw I know, all the tough questions!
> 
> 
> 
> Looking at the socket from the bottom, from either the key-way (on octals) or the space (9 and 7 pin tubes) the first pin on the left is 1, and you go clock-wise around from there


ahh ok- thanks keeps!

so the outer lug of the tone pot, bearing the cap, connects to pin 6 of the 50l6.
and on inspection, it appears the lug that the wiper connects to is actually connected to ground.
those 4 lugs on the 35z5 go to the chassis.

so they are wired the same lol! except on my paul, the wiper is simply soldered to the pot case, rather than run to a ground. 
forgive me you guys, most of my posts in this thread where made either first thing in the morning, or right after work when i shoulda been showering-
typing in haste, inspecting in haste- you know. 
ive got forklift grease all over my keyboard now.


----------



## keeperofthegood

fraser said:


> ahh ok- thanks keeps!
> 
> so the outer lug of the tone pot, bearing the cap, connects to pin 6 of the 50l6.
> and on inspection, it appears the lug that the wiper connects to is actually connected to ground.
> those 4 lugs on the 35z5 go to the chassis.
> 
> so they are wired the same lol! except on my paul, the wiper is simply soldered to the pot case, rather than run to a ground.
> forgive me you guys, most of my posts in this thread where made either first thing in the morning, or right after work when i shoulda been showering-
> typing in haste, inspecting in haste- you know.
> ive got forklift grease all over my keyboard now.


kqoct







http://www.nj7p.org/Tube4.php?tube=50L6GT

But, there isn't anything inside the tube at pin 6... pin 5 would make sense though >_>


----------



## John Bartley

keeperofthegood said:


> But, there isn't anything inside the tube at pin 6... pin 5 would make sense though


Sometimes, when a tube has unused pins (no connection inside the tube to that pin), the corresponding socket connections are used as "tie points". This would be the same as using a lug on a terminal strip and it's very common to see this in tube chassis', especially old radios. The next step in the circuit tracing/troubleshooting is to follow the wiring away from that tie point and see where it goes.

cheers

John


----------



## p_wats

Wow. This really is turning into a very knowledgeable thread. I'm learning more from this $100 tube amp than I ever expected! 

Thanks to everyone who has contributed so far!


----------



## fraser

just double checked- and yeah, if the first pin after the keyway is 1, then going clockwise, the pin in question would be 6- also connected to pin 6 is a wire, including a resistor, from the volume pot-

the keyway is directly in between the red and blue wires at the front of the socket here- making the blue wire tied to pin 1- yes?
you can just see the resistor coming off the bottom lug on the back of the volume pot- it ties to pin 6 as well


----------



## fraser

John Bartley said:


> Sometimes, when a tube has unused pins (no connection inside the tube to that pin), the corresponding socket connections are used as "tie points". This would be the same as using a lug on a terminal strip and it's very common to see this in tube chassis', especially old radios. The next step in the circuit tracing/troubleshooting is to follow the wiring away from that tie point and see where it goes.
> 
> cheers
> 
> John


it goes to the volume pot, but meets some resistance on the way there! cool, thanks john!


----------



## keeperofthegood

50L6 is not as common an output tube (compared to 6L6) so a google on "50L6" has limited responses, however:











This "might" be similar, at least the tone pot here is grounded


----------



## p_wats

Quick update: I finally received the OneAC external isolation transformer/line conditioner recommended earlier in this thread. The result was immediately beneficial--not only can my girlfriend now turn on lights in other parts of the apartment without causing weird noises in the amp, but it also very noticeably reduces the overall hum. 

All I'm left to do now is try a small gig with this bad boy then it's off to Craigslist for my Blues Junior!


----------



## keeperofthegood

p_wats said:


> Quick update: I finally received the OneAC external isolation transformer/line conditioner recommended earlier in this thread. The result was immediately beneficial--not only can my girlfriend now turn on lights in other parts of the apartment without causing weird noises in the amp, but it also very noticeably reduces the overall hum.
> 
> All I'm left to do now is try a small gig with this bad boy then it's off to Craigslist for my Blues Junior!


RIGHT ON!

Next, to get you going on a schematic LOL


----------



## corailz

John Bartley said:


> Edit :: that's just a really cool looking little amp! I think you're lucky to find something like that to play with, especially in such great shape. I keep my eyes open for them too, but I don't see too many like that.


I found one in Québec city for $80 http://montreal.kijiji.ca/c-buy-and...S-FAIT-AU-CANADA-VERS-1964-W0QQAdIdZ180598083

Congrats p_wats for the nice little amp...I like vintage stuff at great price.


----------



## Talisk3r

*First schematic for Paul model 201*

(First post ever, be kind)

I just bought a Paul model 201 like yours. Cool little bug. I like it a lot. I play guitar but i'm sure any harps player will try to snatch it from me. Does yours has a Jensen speaker too?

If I read the thread correctly there is no schematic yet. So I took a few minutes and did this.
http://picasaweb.google.ca/Talisk3r/Paul201#

I know it's ugly but I think it's accurate since it's a fairly simple amp. Didn't figure out a nice way to draw the on/off switch.

My tone control is not working too. Looking at the schematic it's obvious why. The easiest fix would be to move the cap to the already crowded volume pot or to the 50L6 grid, but changing the cap for a 10uF would enable/disable Bypasse cathode bypass. Also using something like 1uF would change the highpass gain of the actual 53kHz to something more useful like 1KHz and therefore create a 'more treble' tone control. The voltage rating need to be twice V_g, something like 50V.

If I can find some benchtime i'll try those idea and keep you posted.


----------



## keeperofthegood

Talisk3r said:


> (First post ever, be kind)
> 
> I just bought a Paul model 201 like yours. Cool little bug. I like it a lot. I play guitar but i'm sure any harps player will try to snatch it from me. Does yours has a Jensen speaker too?
> 
> If I read the thread correctly there is no schematic yet. So I took a few minutes and did this.
> http://picasaweb.google.ca/Talisk3r/Paul201#
> 
> I know it's ugly but I think it's accurate since it's a fairly simple amp. Didn't figure out a nice way to draw the on/off switch.
> 
> My tone control is not working too. Looking at the schematic it's obvious why. The easiest fix would be to move the cap to the already crowded volume pot or to the 50L6 grid, but changing the cap for a 10uF would enable/disable Bypasse cathode bypass. Also using something like 1uF would change the highpass gain of the actual 53kHz to something more useful like 1KHz and therefore create a 'more treble' tone control. The voltage rating need to be twice V_g, something like 50V.
> 
> If I can find some benchtime i'll try those idea and keep you posted.


 Pretty decent. Do you have Photoshop?


----------



## Talisk3r

Sorry no photoshop . I do have real CAD but for me now it serve its purpose as is. I have 2 other similar amp schematic to draw eventually and I prefer invest that time in thinkering with my soldering iron. The problem is thinkering in a small appartement is hard on the neighbords.

I was primarly curious about the non working tone control and the non existent power transformer. I was hoping for a voltage doubler but it's much simpler thant that. The A+ is 130V. 

I'm thinking of using the tone pot for a variable feeback. It's still a kind of tone change so the labeling will still be relevant ;-)


----------



## keeperofthegood

LOL its all good, I would have to look it up again, but there is a 'premade' images file online. All in bmp format. I think it was part of a larger schematics program at one time, but the gentalman that was building this has become a silent key.

*EDIT http://www.qsl.net/wd4nka/TEXTS/Tubepadf.html Though, it is not complete and a number of the links are dead, there is enough left to be useful.*

There are a few parts/points I am unclear on from your schematic, what did I get wrong here (Yes, there are errors).


***** Updated see below ******


----------



## Talisk3r

Wow!!! That is nice a really nice sch.

I don't see any error from what I draw except the confusing part both on my drawing and on the amp that I will try to describe now.
1- AC line is always connected to the fuse where you draw the switch.
2- the switch (which is located on the pot volume) is between the 'ground side of the volume pot and the other AC line. In other word, the CAP/resistor at the bottom of the volume pot is the '"Death Cap". Yes this is the first time I see a resistor beside a 'death cap' (forgot the proper naming for that cap). 

And yes my Paul is still 2 prong cord. I have to think about it but having no Power transformer it might be more complicated and less safe to perform a 3 prong conversion because of all the chassis contact points... not sure. Have to think about it... really busy day/week.

Mathieu


----------



## p_wats

Talisk3r said:


> And yes my Paul is still 2 prong cord. I have to think about it but having no Power transformer it might be more complicated and less safe to perform a 3 prong conversion because of all the chassis contact points... not sure. Have to think about it... really busy day/week.
> 
> Mathieu


A couple amp techs in Toronto told me my 3-prong chord without a power transformer could be doing more harm than good (because of the chassis contact that you mentioned). I've since picked up an external transformer thanks to Keeperofthegood's suggestion and it helped a lot (and I feel safer). 

As for the tone pot, I managed to get mine working (subtly, but definitely alters the treble/bass) by disconnecting the cap from the tube and connecting it to the right side of the bottom turret. However, I'm not sure if I'll leave it there, as I don't quite know what it is actually doing now. 

These days I'm trying to build/find a suitable road case for my Paul, as I'm itching to gig with it!
Also, thetubestore.com says they should be getting stock of the 35z5 tubes soon (they have the others already).


----------



## keeperofthegood

Talisk3r said:


> Wow!!! That is nice a really nice sch.
> 
> I don't see any error from what I draw except the confusing part both on my drawing and on the amp that I will try to describe now.
> 1- AC line is always connected to the fuse where you draw the switch.
> 2- the switch (which is located on the pot volume) is between the 'ground side of the volume pot and the other AC line. In other word, the CAP/resistor at the bottom of the volume pot is the '"Death Cap". Yes this is the first time I see a resistor beside a 'death cap' (forgot the proper naming for that cap).
> 
> And yes my Paul is still 2 prong cord. I have to think about it but having no Power transformer it might be more complicated and less safe to perform a 3 prong conversion because of all the chassis contact points... not sure. Have to think about it... really busy day/week.
> 
> Mathieu


Thank you  I have it as a photoshop doc and did the wiring in blue because it is still being "edited". If you look at the ##L6 tube, I have nothing to the first grid. That was one other area where your schematic confused me a little. Pins 4 and 5 of the 50L6 I need help with.

 and that is an odd arrangement with the switching. How does that turn power on/off for the amp? @[email protected] I must be missing something for sure LOL


----------



## Talisk3r

You are right my drawing is bad in the pentode area. The beam forming grid should be connected to the Cathode and I shouldn't have let a little line hanging there on the right like I did.

According to TDSL of duncan amplification, the pin-out for the 50L6 is:
1: Shell (that trick me once.. :-( )
2: h
3: a
4: g2
5: g
6: Not connected
7: h
8: K
The PIC is much more clear in TDSL.

So you just have to connect the screen grid (which is usually the second grid) to the Screen supply point (B) (no there is no screen resistor on that amp, another possible improvement). But that would look odd on your schematic since your screen grid is on the left... Did you reverse the pic, because usually the cathode connection is on the right? Anyway those are details.

The amp power on/off because the neutral AC is cut from the chassis by a switch located on the schematic on the ground side of the volume pot. I wrote neutral near the end of that line but then again it's pretty hard to read.

I appreciate your effort to decipher my little drawing. I never tough someone would bother otherwise I would use a CAD.


----------



## keeperofthegood

Yup, flipped the image. I did that because it "looks" like you have the signal coming in at pin 4 and not pin 5 and I wanted to draw that straight in. SO, the signal does do in at pin 5 and pin 4 goes to B?


----------



## keeperofthegood

p_wats said:


> A couple amp techs in Toronto told me my 3-prong chord without a power transformer could be doing more harm than good (because of the chassis contact that you mentioned). I've since picked up an external transformer thanks to Keeperofthegood's suggestion and it helped a lot (and I feel safer).
> 
> As for the tone pot, I managed to get mine working (subtly, but definitely alters the treble/bass) by disconnecting the cap from the tube and connecting it to the right side of the bottom turret. However, I'm not sure if I'll leave it there, as I don't quite know what it is actually doing now.
> 
> These days I'm trying to build/find a suitable road case for my Paul, as I'm itching to gig with it!
> Also, thetubestore.com says they should be getting stock of the 35z5 tubes soon (they have the others already).


This is the way I would go http://octopart.com/parts/category--filters--power+supply+filters/search?c=4578 if I were to design an amp today. 



















These will do what the "death cap" did, only these are many times safer.


----------



## Talisk3r

keeperofthegood said:


> Yup, flipped the image. I did that because it "looks" like you have the signal coming in at pin 4 and not pin 5 and I wanted to draw that straight in. SO, the signal does do in at pin 5 and pin 4 goes to B?


Yes exactly signal to pin 5 and B to pin 4. sorry for the confusion.

As for the switch, I was influenced by the layout of the with my Volume pot comment. The point was there is the fuse on one side of the AC line (the black one = live if plug correctly into the wall) and the switch on the other line (the withe one = neutral again if plug correctly). So anywhere between neutral and the other side of the filament in series is ok from a schematic point of view.


----------



## Talisk3r

Look nice. Good suggestion. Didn't about those. I'll probably add a full bridge rectifierbefore the 35Z5 as well.


----------



## Talisk3r

But I look at the schematic, your not isolated with those. It's just filtering.


----------



## keeperofthegood

Talisk3r said:


> But I look at the schematic, your not isolated with those. It's just filtering.


They are "safer" because the internal caps are made to self destruct open circuit and not closed (there is an actual industrial standard to that too). The chassis isn't supposed to be a part of the white or black lead either, just the ground. It is the combination of these makes them safer, not that you are more isolated, but that failure modes are better contained. This would, for me, still also include an isolating transformer of some kind. In more modern switch-mode equipment, the nature of switch-mode circuits means there is usually transformer isolation following the filter circuits.


So, yes, the line filters were only specifically about that death cap  not overall isolation.


----------



## keeperofthegood

Ok here we go, the UPDATE


Let me know if I got this .... better?


----------



## Talisk3r

Yes. That's exactly it as far as I can tell.

BTW take a look at my other little amp.
http://picasaweb.google.ca/Talisk3r
( I know it's too much. I cannot play them in my small appartment anyway.)

One of them has the same Power tube cathode tone control then the Paul. Don't remember if it's working...


----------



## Talisk3r

You are gonna hate me for this but I made others ugly schematics. lol.


----------



## keeperofthegood

Talisk3r said:


> You ar egonna hate me for this but I made other ugly schemaic. lol.



HAHAHAHA no gosh, all is good!!

Download that package I linked up there somewhere. It is a good helper to making schematics!


----------



## p_wats

Thanks for all this work on the schematic guys! I'm learning a lot just trying to catch up. 

I almost bought another one of these little amps the other day. I love mine so much!


----------



## keeperofthegood

p_wats said:


> Thanks for all this work on the schematic guys! I'm learning a lot just trying to catch up.
> 
> I almost bought another one of these little amps the other day. I love mine so much!



Welcome.

This is, for me, FUN. The next update on the Paul schematic will be black wires, clean connections, and all the part values labeled. I just need to know it is accurate and correct, and if there are "mods" to also put those in as well


----------



## p_wats

Well, it's been a while since I started this thread and I've been trying to learn about amp circuits in the meantime, so now I can almost understand what you guys have been talking about! 

I've been using the Paul regularly at shows for the past few months (with an external isolation transformer)--in most cases it works perfectly for a mic'ed gig, but I think I'll keep it more as a recording amp. 

I'm actually starting to understand the schematic posted above and it will prove very helpful in the future I'm sure (I may one day install an internal isolation transformer--as well as full-wave rectification). 

In the meantime, I've ended up with ANOTHER Paul amp--an 801 with 2x8" and tremolo, as well as an old Northland amp, so my plate is full (as is my apartment). 

Next up, getting my feet wet building a 1.5 watt Firefly amp from a PCB I just ordered. Woo!


----------



## dalanglois

Wow! just wanted you to know that I too have an amp looking a lot like these. It's been a while since i search for info on the web, but mine had a "Lark" faceplate and, until today, I didn't find anything as close as this!

Mine seems to be a bit "modified", it's got two speakers in it (one looks like one from a car system), and was given to me after a basement flood... Inside are a 12DW7 preamp tube, a 35W4 rectifier and what looks like a 50c5 power tube

After a power cord/fuse change (and major cleanup) it powered on, but hummed a lot and sounded wobbly. I changed the big 3-in-1 power capacitor with 3 separate (and new) replacements, and now it works pretty much like new!

I still got to add an isolation transformer, and I am thinking about replacing the speaker too.

Here's what it looks like:


----------



## rideough

Here is a schematic for chassis 801. I just picked up an ARC 801 that was refurbished professionally at Kingston Guitar Shop. Sounds and looks awesome.


----------



## keeperofthegood

rideough said:


> Here is a schematic for chassis 801...


Thank you!


----------



## p_wats

rideough said:


> Here is a schematic for chassis 801. I just picked up an ARC 801 that was refurbished professionally at Kingston Guitar Shop. Sounds and looks awesome.


Excellent! Thanks!

I had to do some repairs on mine recently, as something was going on with the switch (was always on when plugged in...but continuity seemed good). Eventually one of the 0.47uf caps literally exploded. All good now though. 

Now that I've actually built a tube amp from scratch I've been thinking about going back into this one and altering the rectifier and adding a power transformer, but I'm also tempted to just leave it stock for posterity's sake.


----------



## Johnny

Paul! Loving that dual 8" PAUL that I got back from you this summer. Nice to see/hear uh, read you here! I'm signed up to take the amp building class here from Trinity amps. I'm looking forward to building my 1st amp and getting some knowledge on the inner workings of them. All the best to you sir!
Here's a look at your old pal PAUL...


----------



## p_wats

Johnny said:


> Paul! Loving that dual 8" PAUL that I got back from you this summer. Nice to see/hear uh, read you here! I'm signed up to take the amp building class here from Trinity amps. I'm looking forward to building my 1st amp and getting some knowledge on the inner workings of them. All the best to you sir!
> Here's a look at your old pal PAUL...


Johnny! I'm glad you're enjoying the amp. I miss that ol' girl. Mine had some problems recently, but still sounds great. 

That amp course is going to be excellent. Here's the one I recently built. I'm sourcing the parts for an old Ampeg build now too.


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## Johnny

Paul, yeah the PAUL is one of my faves and I play it more than my SF Princeton Reverb I have with me. I would someday like to switch out that huge transformer that bulges the back on this amp, so if you ever come across the right transformer and want to switch and keep this one let me know. Your amp looks very cool. I like that you were able to use recycled parts...what a cool idea to use an old record player! NICE!!!


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## rideough

Here's my Arc Chassis 801. Excuse the red lead as realized I can't jump the inputs as I realized after finding the schematic that they are in parallel.


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## Johnny

NICE ARC! Looks to be in pretty good condition. I really love the grill cloth patterns that they used. Wish I could get a hold of some. Anyone know where...?
Here's a 201 that I have...again, the super cool grill cloth.

http://i128.photobucket.com/albums/p195/johnnyangel69/PINE AMP/P1120700.jpg


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## rideough

OK I've got some questions about the 801 now after extensive inexperienced research. 
Is this a safe circuit if there is only the one transformer in it and a 2 prong plug? i've heard some say it is because it is chassis grounded.I've heard some say it isn't because the tube heaters are in series. i am pretty sure the output is 2.3 watts and that's fine by me...loud enough for me as I have a 120 watter for my super loud needs. 
I there any way to find out by reading the schematic if it is an 8 ohm impedance speaker? 
Is this a class A or AB? So many questions!!!! One thing I am certain of is it sounds great!


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## markxander

Just picked up a Trend branded 801 chassis (single 8" Jensen speaker) in Waterloo yesterday!

The tolex is in rough shape, but it works beautifully and it's dead quiet.

It looks cool, but I'm going to use it to practice re-tolexing, and I have a very strong suspicion that I'm going to make it tweeeeeeeed.

Has anybody looked into switching speakers? My first impression is that I have enough room in there to put in a 10", but haven't taken it apart or measured yet...


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## Buzz

Hey cool, I've got an Arc amp just like yours. My tolex has a hole in the front of it. The amp works but it likes to hiss and crackle. i think I need to deoxit the pots.


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## markxander

I didn't go with tweed after all--it was sold out at Steamco and I'm an impatient guy... Thanks to Lens Mill (fabric store my girlfriend suggested), I got $8 worth of this stuff. Hot rod time.










Think I'll get some white piping for around the back panel and grill, and I'll need to decide on a grill cloth material. Q Components in Waterloo seems to carry most of the standards--I'm sort of thinking silverface Fender style--or I could re-use the old wacky grill cloth it came with. Ideas?


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## greco

How is the search for a speaker progressing?

Cheers

Dave


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## markxander

Going to be a little while before I have access to a router (don't want to buy one since I live in a tiny apartment), so it's going to stay an 8" for now!


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## markxander

Some more pics:

















Aaaaaand a little special something else...


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