# Botched the Filter Caps on my Bassmaster!



## Planetsmasher (Feb 7, 2015)

Gents, hello to you all, long time lurker...recent joiner here. I need some help if you can see your way clear..

I have a 68 Bassmaster that was sorely in need of filter cap replacement. I did the research..found out how to drain the old caps off and ordered up the parts. The old Mallory caps of course only have 2 leads while the F&T's that I got to replace them have 3. After some reading I determined that the negative lug could just be grounded to the chassis, which is how I did it. As far as the rest, I put the wire back on the new cans precisely like the old ones came off. That being said, the Mallory cans have a pair of symbols.. a triangle and a D. The F&T's just have the two positives and a neg, so I had no reference anyways. In addition, the one Mallory had its two leads squeezed together, and all the wiring to that Capacitor was soldered in one spot. I couldn't do it with the F&T's so I made a little bridge between the two lugs and joined them that way. Long story short= not a peep out of the amp now. Oh, there's the hum when it gets turned on, but nothing else.

What the heck guys? What could have went wrong with such a simple little procedure?


----------



## Planetsmasher (Feb 7, 2015)

To make it simpler, this is the route of any wire that's attached to the Filter Caps now, with the rest of it omitted for clarity. I have the schematic guys, but I may as well be looking at a string of DNA for all the sense I can make of it. Thanks for any input you might have.


----------



## keto (May 23, 2006)

I think the F&T's are 2 caps inside 1 body, that could be what's causing the issue? I mean, I'm pretty sure that's why they have dual leads out one end.

Also, the single (assumed negative) end has to go back into the circuit where it was before, makes no sense to me that you could just ground it to the chassis.

I can't blow up your attachments for a closer look unfortunately.


----------



## WCGill (Mar 27, 2009)

Yup, can't see a thing with the small images.


----------



## Planetsmasher (Feb 7, 2015)

how is this instead:

http://s776.photobucket.com/user/planetsmasher66/library/


----------



## epis (Feb 25, 2012)

Well, you did a few mistakes, there is no need for that bridge you made, check out that black wire (probably ground)
Your old caps had visually clear ground tabs on casing, new ones have ground in the middle - minus.
Check out the images in this link, it should help.

http://www.thegearpage.net/board/showthread.php?t=1497502

Just friendly advice, next time take a few images of the chassis or make a sketch of wiring before start desoldering . And improve your soldering skills.
Cheers, Damir

P.S.

For ground connections, get some ground lugs and star washers, there is no need to struggle with soldering to the chassis.
This is a must for mains ground connection.


----------



## dcole (Oct 8, 2008)

My suggestion is you don't do this stuff unless you actually know what you are doing. It is dangerous to just go in blind even if you read about draining caps. Not knowing how to read the schematic is my first indication you don't know electronics and the looks of your soldering is my second indication. I am not trying to be a dink here as you could end up doing some serious damage to your amp or yourself. Please take it to a repair tech and have them do it properly.


----------



## Planetsmasher (Feb 7, 2015)

Thank Damir, that is the same layout as my amp. In post #14 you can see pretty well. Those tabs on the right can are pushed together and it's all soldered at a common spot. Are you saying that because of the way the F&T's are made, that it just isn't required now? As well, that black wire was definitely soldered to one of the leads on the old Mallory can. Again, are you suggesting that's not necessary with the new style capacitor?

I'm working on the soldering.


----------



## epis (Feb 25, 2012)

Your new caps are same double capacitors in one can, you have two separate positive lugs and negative in the middle.
You did understand that part. Remove that short you made on the right can, use the images of original wiring, check out wher goes that black wire you put on the positive lug.


----------



## Planetsmasher (Feb 7, 2015)

You are correct dcole, I don't know terribly much about electronics.. and my soldering isn't professional. That's why I'm here asking some questions. I couldn't change the alternator on my truck either, until I convinced my self that I should just try, and see how it went. Made a mistake with that as well, but I got it in the end. I appreciate what you're saying to me, but I am not ready to give up just yet.


----------



## nonreverb (Sep 19, 2006)

Does this happen to have a choke transformer?
Got a meter?


----------



## Planetsmasher (Feb 7, 2015)

Yes, it has a choke. Yes I have a multimeter and was using to ensure caps discharged before proceeding.


----------



## epis (Feb 25, 2012)

I have checked out wrong diagram, I apologize . Your amp is version with choke, first two filter caps are indeed in parallel. It seams you did put all the wires in right spots.
Measure the voltages on them, and let us know.


----------



## nonreverb (Sep 19, 2006)

It may be something unrelated to the power supply as the wiring appears correct. Did you do anything other than the power supply caps?
If I were you, I'd reflow the solder joints to ground on both those caps. Perhaps change the red wire entirely. It doen't look like it has a good solder connection to the chassis.


----------



## Planetsmasher (Feb 7, 2015)

Well, now that you mention it, I changed both of the volume pots, to 1m
audio taper pots and removed the bright cap off of the lead channel. in it's place put a 470k resistor a'la the famous "parkhead mod". That was it though. And those solder connections are rock solid.

I will look at those ground to chassis connections, but they seem to have grabbed really good.


----------



## dtsaudio (Apr 15, 2009)

I hope the


> 1K audio taper pots


 is a typo. The originals were 4 meg were they not?


----------



## Planetsmasher (Feb 7, 2015)

Correct, and now they are 1m audio pots.. my bad (
edited original)


----------



## Church-Audio (Sep 27, 2014)

I would redo all of this it looks like crap no offence. But if you don't know what your doing playing around with high voltage is not a good place to start. This is how it should look. This takes a few tools
1 green lee knockout punches $390 per set
2 good quality high wattage soldering iron $175
3 Skill and expirance.

when you do wirk like this you can be liable if someone gets hurt or worse yet killed because of your work. You have no idea if your going to sell this amp or keep it..... I see this all the time. 

If if you want to learn start with building a small amp kit like a tweed champ mojotone make great kits that sound amazing. Start small. Doing a cap job like this properly involves having the right tools. The last thing you want to do us make your amp worth less and unsafe with sloppy work. And the most important tip is this... When ever your start a project where you have to replace parts take pictures!!! Before and after so you can compare them. Before your power your amp on. Invest in a current limiter or make one ( Google) is your friend. Check out some books like Gerald Webers books and videos I don't agree with everything he does but he will get you in the ball park. Don't mean to be rude but I don't work on my own car I could but I don't have the right tools or expiance to do the job right so I leave it to the pros. But if you want to get into doing this start slow and never do work that looks like that again. Plan out your job come in here and ask the best way to accomplish your task. Most of us are very friendly and more than willing to help!! But like others have said drawing out the circuit Also helps you understand what's going on  one last thing check out the tube amp handbook


----------



## Planetsmasher (Feb 7, 2015)

Thank you Mr. Church. I do however have some idea if I am going to keep this amp or sell it. And actually, when I bought it it had an ungrounded 2 prong cord, so it's had a significant safety upgrade already.

As you have alluded to, my work was not professional grade. yes I understand. Getting experiEnce, as you advised though.. means doing it. Maybe fucking it up, and re-doing it... but it all starts with taking the plunge. Is this circuit pictured above from a Traynor YBA-1, or are you just showing me how neat solder joints can be? I'm not being facetious or snarky... genuine question.


----------



## jb welder (Sep 14, 2010)

How about some pics of the pots you changed.


----------



## Planetsmasher (Feb 7, 2015)

jb welder said:


> How about some pics of the pots you changed.


sure, it's added to the photobucket file

http://s776.photobucket.com/user/planetsmasher66/media/pots.jpg.html


----------



## Church-Audio (Sep 27, 2014)

I forget what amp that is I have done so many. I just get concernened when I see work that is dangerous. And to be honest you never know who is going to end up with an amp GAS and just becoming bored with a sound are quite common and have lead to guys like me owning hundreds of amps over the 39 years I have been playing. Good luck with your projects remember neat 9x out of 10 = safe


----------



## Church-Audio (Sep 27, 2014)

Planetsmasher said:


> sure, it's added to the photobucket file
> 
> http://s776.photobucket.com/user/planetsmasher66/media/pots.jpg.html


The pots look perfect!!! Good job, to bad about the values but what ever that's easy to fix. Would not be the first time I have put in the wrong part lol I once put in 470k screen resistors on a fender amp and wondered why I could not get much signal out of the amp for some reason lol shit happens I did not mean to sound so harsh it looks like to me you have the skills to do a good job just need to plan the bigger jobs a bit more. This is the main iron I use for soldering anything to a chassis it works like a dream ! One last tip change out the bias filter caps the blue Philips ones... Can't hurt to have good caps for the bias supply.


----------



## Planetsmasher (Feb 7, 2015)

That's interesting... I did a lot of digging and the 1M-A pots were a consensus. The resistor was pretty much an overwhelming hit as well. I just couldn't stand how sharp the high end was at lower volumes. Really obnoxious with a Tele on the bridge PU actually. the capacitor is just an extension on removing the bright cap from volume 2 pot. 

at any rate, I'm still missing the last pieces of the puzzle if anyone can add anything.


----------



## dcole (Oct 8, 2008)

Planetsmasher said:


> Thank you Mr. Church. I do however have some idea if I am going to keep this amp or sell it. And actually, when I bought it it had an ungrounded 2 prong cord, so it's had a significant safety upgrade already.
> 
> As you have alluded to, my work was not professional grade. yes I understand. Getting experiEnce, as you advised though.. means doing it. Maybe fucking it up, and re-doing it... but it all starts with taking the plunge. Is this circuit pictured above from a Traynor YBA-1, or are you just showing me how neat solder joints can be? I'm not being facetious or snarky... genuine question.


I think the point of our concern is that you should be looking for someone experienced to learn from. I personally took Electronics Engineering Technology. I learned how to read schematics and solder. I then spent 2 1/2 years working in a coal fired power plant and learned how to safely work around high voltages. When I decided to work on tube amps, I had a lot of background to work on them safely.

There is a difference between just diving in to learn and going in blindly. You wouldn't want to just jump into a lion cage and start trying to tame the thing. In a sense this is what you are doing. Its best to find someone experienced to work with you in person to learn something like this.


----------



## Church-Audio (Sep 27, 2014)

I don't know if it's the wrong part or not have not looked at a schematic. Just going off what someone else mentioned 1 meg is a marshall and fender value usually.


----------



## JCM50 (Oct 5, 2011)

Planetsmasher said:


> You are correct dcole, I don't know terribly much about electronics.. and my soldering isn't professional.


And bad soldering skills will kill the caps before you even turn the amp on. Sometimes, dealing with an experienced tech is cheaper/faster. Learn on easier projects 1st and work yourself up.


----------



## parkhead (Aug 14, 2009)

Planetsmasher said:


> Gents, hello to you all, long time lurker...recent joiner here. I need some help if you can see your way clear..
> 
> I have a 68 Bassmaster that was sorely in need of filter cap replacement. I did the research..found out how to drain the old caps off and ordered up the parts. The old Mallory caps of course only have 2 leads while the F&T's that I got to replace them have 3. After some reading I determined that the negative lug could just be grounded to the chassis, which is how I did it. As far as the rest, I put the wire back on the new cans precisely like the old ones came off. That being said, the Mallory cans have a pair of symbols.. a triangle and a D. The F&T's just have the two positives and a neg, so I had no reference anyways. In addition, the one Mallory had its two leads squeezed together, and all the wiring to that Capacitor was soldered in one spot. I couldn't do it with the F&T's so I made a little bridge between the two lugs and joined them that way. Long story short= not a peep out of the amp now. Oh, there's the hum when it gets turned on, but nothing else.
> 
> What the heck guys? What could have went wrong with such a simple little procedure?


ok first things first reading your post you did it right and used the right parts !!
However, getting all the instructions right ,and doing your assembly work 100% perfect, is most important for saftey with the power supply. 

The first clue is you have no sound but do have a hum ..
if it is a very low level hum is it the sound of the power transformer charging ? 

the first thing to do when you end up in this situation is 
A) check your work .. you may have disturbed another wire ? 
B) check your grounds did you get all of them ? they are never drawn well in schematics so they are kind of an assumed thing 
c) check your connections with a continuity meter, then check your voltages 

I bet you have no power beyond the diodes 
as someone mentioned look for silly errors like using a 470k screen grid instead of a 470 ohm 

True story: I was working on an amp design with a engineer and quickly made some changes over an existing schematic and faxed it off to the engineer. 
The next day he called and said "did you really mean to put this value here?" "if you do you will get some extra distortion ?"
I admitted my mistake (oops sorry I meant to change this value...) but went home and tried the mistake. 
The added distortion sounded great and a version of the mistake appeared in the final amp lol 

p


----------



## parkhead (Aug 14, 2009)

keto said:


> I think the F&T's are 2 caps inside 1 body, that could be what's causing the issue? I mean, I'm pretty sure that's why they have dual leads out one end.
> 
> Also, the single (assumed negative) end has to go back into the circuit where it was before, makes no sense to me that you could just ground it to the chassis.
> 
> I can't blow up your attachments for a closer look unfortunately.


f&t are the right choice yes there are two caps in the one can with a common ground 

The negative goes to ground .. anywhere ... but closer to the main power ground is potentially quieter and closer to any signal ground is potentially noisier 

the old mllory caps were 40 + 40 with the common ground the outer casing/chassis shell
so the negative connection was the 4 solder taps grounded to the chassis 
the the terminals had shaped markings because they also made 40/20/20 caps as well as 40/10/10 ect so the markings coresponded to the 10uf or whatever 
in the bassmaster it does not matter which terminal you use as long as you make the connections cleanly


P


----------



## jb welder (Sep 14, 2010)

Connections to chassis are extremely difficult without a big iron. If you end up with a "blob", grab it with pliers and try to twist or pull on it. If it snaps free it was not a good connection. Where your red wire from the cap connects to chassis, I think this may be the case..


----------



## Church-Audio (Sep 27, 2014)

I think this guy needs to realize that doing work like this CAN kill you. How easy? you dont have a safety ground because an outlet is wired wrong and the cap shorts out to ground voltage now flows on the ground through your body to say a microphone. And guess what it only takes 20mA when you are doing work like this ask yourself the question do I really know what I am doing? If the honest answer is no take it to a real tech. And the fact that you had to drill out the old caps tells me you dont have the right iron to solder new ones back in. You did not use locktight on the screws holding the caps. As others have mentioned there seems to be a blob of solder between the + and the chassis and the wires going to the + terminals are bare and unprotected. I think we would all feel much better if you atleast take it to a tech and have them properly redo that soldering and solder it in there correctly. And not leave all that insulation off the wires going to the + terminals. Then look at what the tech has done and learn from that. I would do it for FREE if you were in my area just because I hate to see work like this when someone is actually playing the amp. Hell even when they aren't going to play it I hate to see work like this! And I am not being some snob when it comes to safety man take no chances. Here is a picture of some work done by a local tech that is very well know in this forum and I am not going to mention names but he used WAX Fing string and Hockey tape to secure the capacitors inside a vintage gibson amp when I got the amp the + was about 1 mm from the chassis and ready to short out!


----------



## epis (Feb 25, 2012)

When we're talking about soldering to chassis,what works for me is micro torch, person just needs to be very careful not to burn his (her) fingers or the components and wires in the chassis.
I prepare the wire by tinning it, make some kind of fence around future solder spot of metal sheet or triple folded aluminum foil.
I apply the flame under some angle more than 90 degrees, but carefully choose the direction of "ricochet".
When it's hot enough, try it with solder wire, make nice puddle of solder and dip the wire in it. I blow at solder spot to cool it down faster.
But, pay attention, it will be hot for a while.
In Planetsmasher's case, I would use a lug instead, or remove new caps before doing it.


----------



## Planetsmasher (Feb 7, 2015)

parkhead said:


> ok first things first reading your post you did it right and used the right parts !!
> However, getting all the instructions right ,and doing your assembly work 100% perfect, is most important for saftey with the power supply.
> 
> The first clue is you have no sound but do have a hum ..
> ...


Ok, I checked continuity of my connections throughout and all were sound with the exception of one of the volume pots I changed. It looked great but the meter told the tale. Re-did the connection and it shows continuity now. As far as the hum, it sounds just like when you first turn the amp on with your guitar volume down.. no better, no worse. my solder globs as grounding points to the chassis I agree, look like hell, and I am going to but a lug on the bolt that's holding the new can in and use that instead. The resistor across the volume pot is a 470Kohm, 1 watt piece, although looking at pictures from other 'parkhead mod' threads, the one I've put in seems enormous in comparison. I will be removing it altogether to see if this is part/all of my problem.


----------



## epis (Feb 25, 2012)

Hi Planetsmasher, just a hum from the amp (not the speaker)usually means overloaded power supply, so we assumed, because of your work on the caps something was short.
Because you did the work in preamp as well, we need to pinpoint the problem to the area of preamp or poweramp.
Easy way to check poweramp and phase invertor is to introduce some signal (hum) to the middle lug of treble pot.
Just to be safe, measure the dc voltage at the lug first. If there is no high voltage present, take screwdriver by the metal part and touch only middle lug (viper)
You should get loud hum at the speaker. That means poweramp is working.
If it passed the test, do the same at volume pots, but first set the volume levels at half.
WHEN DOING THESE TESTS DO NOT TOUCH ANY OTHER PART OF THE CHASSIS WITH OTHER HAND ! USE ONE HAND ONLY

P.S.
Do you have high dc voltages present at the caps you have replaced ?


----------



## Planetsmasher (Feb 7, 2015)

HAHA!!!!!!

Well gents, it looks as if we have a happy ending for this little story. I re-did what looked to be a dodgy ground on the volume pot, and put the Capacitor can grounds on lugs, as opposed to the puddles (even though the meter said they were fine). One of those two was it, because I turned it on and she roared to life!! Put it back into it's box and fastened everything down and tried it again.. Everything works perfectly! I can't honestly say it's any quieter than it was before, but it does sound different. I cannot crank it up right now because the mrs. is having one of the girls around, but I'll be giving it a good hard run soon.

Thanks very much for everyone who gave any constructive feedback... I really appreciate the help. I'm very glad to have been able to handle this one in house..so to speak.


----------



## nonreverb (Sep 19, 2006)

Well done! You need a very hot gun to solder to the chassis as heat dissipation is a major concern. As a rule, I usually pull out the big Weller 200 watt gun for doing chassis joints. Nothing less is worth it.


----------



## JCM50 (Oct 5, 2011)

Great news!


----------



## parkhead (Aug 14, 2009)

excellent !!! 
it is always the way 

p


----------

