# Simple but safe?



## Johnny (Nov 30, 2010)

Hello,

I have a small vintage Canadian built PEPCO tube amp that has a broken solder connection from the TONE pot. I have a solder gun and some solder wire and want to reconnect so that I can use the TONE function. The amp has not been turned on for about a month and it looks simple enough to fix, but I want to be safe. Any suggestions? Is this something that can be done without having to discharge the volts from an amp? And, if needed to take away charge from amp, how is that done?

Tone knob is on right. You can see the wire that is connected to it.


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## tbellisario (Apr 14, 2010)

Johnny,
If you are not familiar with the discharge proceedure I would not recommend performing this fix yourself.
For fear of you not being 100% accurate I cannot in good faith walk you through the proceedure. There are deadly voltages of 450 volts plus stored in capacitors that can be fatal if you touch a connection to one. The tube sockets south of the tone pot in your photograph are connected to these high voltages. Perhaps a member of this site could do the work for you. It is a 2 minute fix.
If you lived close to me I would do it for free. I am north of Brampton if it is worth the gas let me know.


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## Johnny (Nov 30, 2010)

Thanks for the warning; I appreciate it and your willingness to help. It's not a pressing matter at this point, just something I intend to fix one of these days.


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## tribi9 (Sep 19, 2006)

I believe you have a "widowmaker" amp there. Is there a Power Transformer on that thing? If there isn't, I recommend you don't play it until you get an isolation transformer.


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## ajcoholic (Feb 5, 2006)

Johnny said:


> Hello,
> 
> I have a small vintage Canadian built PEPCO tube amp that has a broken solder connection from the TONE pot. I have a solder gun and some solder wire and want to reconnect so that I can use the TONE function. The amp has not been turned on for about a month and it looks simple enough to fix, but I want to be safe. Any suggestions? Is this something that can be done without having to discharge the volts from an amp? And, if needed to take away charge from amp, how is that done?
> 
> Tone knob is on right. You can see the wire that is connected to it.


If you have a multimeter, just take a reading on the larger caps from either end to the chassis (or across the cap itself). I would think after a month they will be discharged. Generally, you might read a very weak voltage (like well under a volt). If you read some residual voltage, you can take your multimeter leads, and drain the capacitor by shorting to ground. I wouldnt do this if you have just powered it up, but after a month like I said I would be very surprised to see any stored voltage in the caps. Also, try flipping the standby or on switch (without the amp plugged in) to drain the remaining stored energy, some amps will self discharge this way.

If you measure no high voltages stored in the caps, you are good to go. Thats the only thing that can be potentially dangerous - again assuming the amp is not plugged in. The caps can store the high working voltages, but not forever. If you read nothing, there is nothing there to hurt you.

AJC


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## fraser (Feb 24, 2007)

man, that looks familiar-
does it look like this?









inside


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## Johnny (Nov 30, 2010)

Looks like this:
front








top








inside








tube layout








speaker


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## Johnny (Nov 30, 2010)

To AJC

Thanks for the tips there. I just bought a multimeter for the amp building course offered here and have yet to use it, so this would be good practice for me. So, to read across the cap I would take the multimeter leads and touch both sides of cap lengthwise (blue ones on end) to get a reading? Or touch one end (either end?) and the other to the chassis to get a reading? Also, (sorry for my newby status over-inquiry) how do you drain capacitor by shorting to ground (what/where is the ground?). 
If I were to flip the ON switch, how long would I need to leave it on for?
Also, once I feel everything is good to go, where do I make connection from that tone pot to...?
http://i128.photobucket.com/albums/p195/johnnyangel69/PINE AMP/P1120708.jpg

Thanks again.


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## ajcoholic (Feb 5, 2006)

Yes you can drain the caps by connecting each end together, or the + end to anywhere on the chassis, assuming it is grounded. If there is little left in the caps, you can just short out the cap to ground with a multimeter lead. If you read still a fairly high voltage you can use a resistor in series with the lead to drain the cap and not get a spark/arc.

If you are not sure where the broken wire is supposed to go, I cant help with that, I assumed you had thebroken wire and just wanted to resolder it Perhaps the guys at the course can help with that?

AJC


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## Johnny (Nov 30, 2010)

Thanks for the quick reply. No, this amp was like this when I got it. Fraser, above, sent a pic of his amp which looks very similar to this. Good idea about taking to the course if not mended by then. I'm in the middle of a move so I probably won't even get to test until after the new year. BTW, that's a TRAMP in garnet red cab that you have eh? Looks nice. I see you've been busy the last couple days putting that together. Any more test drives with the TRAMP?


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## fraser (Feb 24, 2007)

mine is a 201 as well- same amp but yours looks cooler. or more cool- i dunno how that works
your caps have been done- is there 2 transformers?


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## Johnny (Nov 30, 2010)

No, just the one transformer. I got the amp like this over the summer. It was missing the back but I made one from an old piece of wood that I found on the curb. I bought some vinyl covering at Fabricland and covered it (not so well, but ok) definitely not as cool as the original tolex, but better than having the internals open and showing. Here are some more pics:
Transformer and tubes








The missing link 








New DIY back cover








Front and side view


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## Johnny (Nov 30, 2010)

ajcoholic said:


> If you are not sure where the broken wire is supposed to go, I cant help with that, I assumed you had thebroken wire and just wanted to resolder it
> AJC


AJC

I found a picture that I took of this a while ago that shows part of the original(?) connection. Does this look right?
Located in this pic (slightly off center lower bottom left) broken solder connection shown at white wire:
http://i128.photobucket.com/albums/p195/johnnyangel69/P1140010.jpg


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## tribi9 (Sep 19, 2006)

Ok, so it is a widowmaker. I suggest you google that up and don't play until you get an isolation transformer unless you really want to risk getting shocked.


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## Johnny (Nov 30, 2010)

Thanks for the tip. I've only had this for a few months and have played it minimally. I have heard the widowmaker term used before and have just looked it up online and realize the hazard. I will probably leave it alone until I can have it looked at or feel confident in my own abilities. I couldn't pass it up based on the looks. Thanks for the heads up and sorry I didn't respond to your earlier post.


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## Blue_Tokai (Dec 8, 2010)

Looking at the pix of those two amp... it appears that your 'broken connection' is actually a missing capacitor. Cant tell you what value it should be, but perhaps one of the guys that own one of these babies can tell you than you can replace it.
Take ALL the safety precautions that everyone has told you VERY seriously. Those old amps hold very lethal voltages. Hope you get her fixed up.


Cheers,

Russ


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## Johnny (Nov 30, 2010)

Blue_Tokai said:


> Looking at the pix of those two amp... it appears that your 'broken connection' is actually a missing capacitor. Cant tell you what value it should be, but perhaps one of the guys that own one of these babies can tell you than you can replace it.
> Take ALL the safety precautions that everyone has told you VERY seriously. Those old amps hold very lethal voltages. Hope you get her fixed up.
> 
> 
> ...



Thanks Russ. I will definitely not be doing any work here until I am confident in my own skills or can have someone talented enough to help me.

Johnny


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## fraser (Feb 24, 2007)

indeed, a missing cap.









on mine, the red wire insulates one leg of the cap, which is connected to lug 3 of the pot.
the other end goes to pin 8 of the 50l6 (on mine the pins of the tube socket are numbered).
value of the cap is .02uf
you can see where the connections on yours are cut, makes it easy!


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## fraser (Feb 24, 2007)

weird- double post


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