# Cracked circuit board



## guitar69freak (Jul 29, 2019)

What is my best option to “plastic weld” this circuit board?


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## player99 (Sep 5, 2019)

Plastic epoxy and jumper all traces?


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## cboutilier (Jan 12, 2016)

You can probably order an unpopulated replacement board fairly cheap


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## greco (Jul 15, 2007)

Is it for this amp? 
The one with the feedback issues?


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## guitar69freak (Jul 29, 2019)

greco said:


> Is it for this amp?
> The one with the feedback issues?


Yes I’d just gotten some new caps and I just need to epoxy the circuit board and trace the leads.


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## guitar69freak (Jul 29, 2019)

I plan on using contact cement with something to reinforce it and use lengths of speaker wire to complete the circuit board. 

What would you suggest?


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## oldjoat (Apr 4, 2019)

5 minute epoxy ( dollar store cheap stuff ) ... then solder jumpers in place with rosin core solder

use 22 or lighter gauge wire to solder jumpers between the existing mounting holes/ components 

some solid old bell house wire would work fine.


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## greco (Jul 15, 2007)

guitar69freak said:


> What would you suggest?


Save up for a new amp. Seriously.

Convert that amp into an extension cab.


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## guitar69freak (Jul 29, 2019)

I’ve decided to use PL Construction for more rigidity, I’ll let you know how that goes tomorrow.


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## Verne (Dec 29, 2018)

greco said:


> Save up for a new amp. Seriously.


I'd be looking at this as a learning situation. If it won't cost a lot, why not try and fix it and see how you do.


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## Lincoln (Jun 2, 2008)

how tall was the building you threw it off of?


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## oldjoat (Apr 4, 2019)

PL will stay flexi even after curing ... not a good choice ,
epoxy is cheap and you can add several layers to build it up ... even add a strip or two of cardboard top and bottom to prevent flex .
if you ARE looking for a flexi joint , just use a hot glue stick and the cardboard trick ...


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## greco (Jul 15, 2007)

Verne said:


> I'd be looking at this as a learning situation. If it won't cost a lot, why not try and fix it and see how you do.


Good idea. 

Good Luck.


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## oldjoat (Apr 4, 2019)

errr.... that's why you jumper to the nearest solder joint .
and if any tracks run beside each other , try to twist the insulated repair wires together to avoid them becoming antennas ( like you twist tube heater wires )


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## mhammer (Nov 30, 2007)

The green stuff sprayed on the copper side will not take kindly to any solder. Were it my amp, I would scrape the coating away to reveal bare shiny copper, and use pieces of solid-core wire of sufficient gauge (I suspect #20 at least) to connect the two pieces of the board, once it has been epoxied or otherwise glued back together. For those portions that are wide, use a few pieces of wire to connect the edges. That should provide enough rigidity, in combination with the glue and the board-mounted pots attaching it to the chassis.

Just out of curiosity, how did it break?


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## oldjoat (Apr 4, 2019)

from the IC's I'd guess almost any wire down to 30 would work well enough ( so bell wire was suggested )

yes cleaning the board coating and soldering to the tracks would be best , but few people bother to shape and dress a soldering iron tip properly.


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## jb welder (Sep 14, 2010)

Like others have said, you need to use epoxy or jb weld (no affiliation  ).
Hopefully that push button switch at the crack is not damaged.

The up-side is that repairing this will probably cure the squealing.


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## greco (Jul 15, 2007)

jb welder said:


> The up-side is that repairing this will probably cure the squealing.


Your profound optimism is always so invigorating. 

Was the original (i.e., pre "cracked" circuit board era) cause of the squealing ever determined?


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## jb welder (Sep 14, 2010)

greco said:


> Was the original (i.e., pre "cracked" circuit board era) cause of the squealing ever determined?


No, I don't think it was. Of course I'm assuming the crack was already there and is not a new issue. Looking at the older pic here, I don't see the crack, so I hope it's not something that happened now.


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## guitar69freak (Jul 29, 2019)

I had


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## guitar69freak (Jul 29, 2019)

I have a feeling this amp is done. It was given to me not working and I’d invested $5 to replace the power cord that had been cut off. I’d just gotten 2 capacitors in the mail to replace on this circuit board but I may as well return them and call it a day.


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## oldjoat (Apr 4, 2019)

OK ... salvage one of the jacks and wire it up as just a speaker cab ... then replace the rest of the guts to make it look OK ( but not a functional amp )

but since you've gotten this far, why not solder in the jumpers and try it anyway ? ( nothing to lose ) .


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## guitar69freak (Jul 29, 2019)

Is it worth the effort for the $30 I might get for this amplifier?


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## oldjoat (Apr 4, 2019)

one word ... NO 

for a learning exp ... maybe , if you feel inclined .

just wire up the speaker to a jack and sell it for 20 as a speaker box ( no amp )


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## greco (Jul 15, 2007)

@oldjoat See post #8


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## oldjoat (Apr 4, 2019)

just agreeing with you ...

if he wants to try fixing it, OK , nothing lost 
is it worth the time / money ... no

is it worth anything , no ( fixed or not )


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## nonreverb (Sep 19, 2006)

It's amazing how much time and effort has been spent on this amp. None of us wouldn't have given this a second look had it landed in the shop. I commend you all....


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## oldjoat (Apr 4, 2019)

nope . not the amp ... the person 

a lot of people trying to "Help " a fellow member fix something 
passing on some knowledge ( if the member wants it ) 
and encouraging him to "try" ... with nothing to lose.


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## player99 (Sep 5, 2019)

I need to know how the board got broken.


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## nonreverb (Sep 19, 2006)

oldjoat said:


> nope . not the amp ... the person
> 
> a lot of people trying to "Help " a fellow member fix something
> passing on some knowledge ( if the member wants it )
> and encouraging him to "try" ... with nothing to lose.


No...I mean the amp. Problem is, there is no real knowledge about electronics repair being imparted here. We're fixing an amp for him. If he were to bring another broken amp to this forum, we'd be pressing repeat. He has no experience with electronics therefor, we are servicing it....he just does what he's told. Answering the question "how" to fix is easy.....Answering the question "why" or "what's the cause" is a far more difficult concept. Had this amp not had a broken board and was squealing....we'd be here for a loooong time.....and we still don't know if that's even the fix yet......
More importantly, suppose he comes in next with a tube amp with issues. If he doesn't have a clue about tube amps and their inherent dangers, are you going to be the one to wade into that mire knowing that? I'm very careful when it comes to folks getting knee deep into something they know nothing about.


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## oldjoat (Apr 4, 2019)

solid state ... low voltages and small caps so poke away... wear dish washing gloves and use a small screw drive to inject a signal near the input jacks 

Tubes = HV and lethal caps ... take it to a shop if you don't know what you're doing.

everyone starts somewhere ... some pick it up others don't . 
but ya never go anywhere without asking questions and trying stuff.


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## nonreverb (Sep 19, 2006)

oldjoat said:


> solid state ... low voltages and small caps so poke away... wear dish washing gloves and use a small screw drive to inject a signal near the input jacks
> 
> Tubes = HV and lethal caps ... take it to a shop if you don't know what you're doing.
> 
> ...


Maybe so but sending folks into amps where 120VAC is present is no different. Remember, novices don't always know where to and...more importantly NOT to put their fingers in any amp or unplug for that matter. No offense to the OP but based on his multiple posts, he really doesn't know anything about amp repair. As techs, we have an obligation to read between the lines when it comes to giving advice. If someone posts here and speaks the language indicating he knows what he's talking about...great! However, "0" knowledge is a bit different and that must be taken into consideration. Yes I agree that imparting our collective wisdom is a good thing....having said that, we have the responsibility to know when to say no.....my 2 cents. I am now climbing off the podium.


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## greco (Jul 15, 2007)

oldjoat said:


> but ya never go anywhere without asking questions and trying stuff.


One might also want to start by reading several books and watching many tutorials ...followed by experimenting with some 9VDC battery circuits with some basic test/measure equipment.




nonreverb said:


> Maybe so but sending folks into amps where *120VAC is present* is no different. Remember, novices don't always know where to and...more importantly NOT to put their fingers in any amp or unplug for that matter. No offense to the OP but based on his multiple posts, he really doesn't know anything about amp repair. As techs, we have an obligation to read between the lines when it comes to giving advice. If someone posts here and speaks the language indicating he knows what he's talking about...great! However, "0" knowledge is a bit different and that must be taken into consideration. Yes I agree that imparting our collective wisdom is a good thing....having said that, we have the responsibility to know when to say no.....my 2 cents. *I am now climbing off the podium*.


Well written with many excellent points. 

Stay on the podium. Your thinking is very well grounded 
(pun is intended and spontaneous...not bad 'eh?)


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