Burt up PCB, mostly from fire or acid? Fixable?

Thread Starter

MrSoftware

Joined Oct 29, 2013
1,811
I'm debating on making the effort to fix this, and my big questions are (1) will this goop kill the tips on my iron and desoldering station, and (2) is the damage mostly from fire or capacitor electrolyte?

Long story short; a speaker wire got pinched against the chassis of my car shorting out the amp and releasing copious amounts of magic smoke. The amp sat unused for a couple of years and I just now cracked it open to see the damage, and this is what I found (this picture is AFTER I cleaned it up):

bottom.jpg top.JPG

It's clear the heat from the traces burning burnt right through the PCB and into the bottom of the caps that are circled in the "top" photo, eventually spilling electrolyte all over the PCB. The PCB is now squishy and wet in that black area, despite my efforts to clean it up with denatured alcohol and a tooth brush. I'm thinking I can fix it using wires to replace the traces if I can find a schematic, but will the electrolyte that's absorbed into the PCB continue to cause problems? i.e. is it corrosive? Has anyone dealt with this type of mess before and have any tips on cleanup?
 

ian field

Joined Oct 27, 2012
6,539
I'm debating on making the effort to fix this, and my big questions are (1) will this goop kill the tips on my iron and desoldering station, and (2) is the damage mostly from fire or capacitor electrolyte?

Long story short; a speaker wire got pinched against the chassis of my car shorting out the amp and releasing copious amounts of magic smoke. The amp sat unused for a couple of years and I just now cracked it open to see the damage, and this is what I found (this picture is AFTER I cleaned it up):

View attachment 95878 View attachment 95879

It's clear the heat from the traces burning burnt right through the PCB and into the bottom of the caps that are circled in the "top" photo, eventually spilling electrolyte all over the PCB. The PCB is now squishy and wet in that black area, despite my efforts to clean it up with denatured alcohol and a tooth brush. I'm thinking I can fix it using wires to replace the traces if I can find a schematic, but will the electrolyte that's absorbed into the PCB continue to cause problems? i.e. is it corrosive? Has anyone dealt with this type of mess before and have any tips on cleanup?
The only thing you can do with that is; file out the charred PCB material and build up replacements for the destroyed tracks with tinned copper wire.

Obviously that means you need to know where all the destroyed tracks used to go.
 

DerStrom8

Joined Feb 20, 2011
2,390
I agree with Ian, unless you're extremely lucky and have a thorough understanding of how everything was originally connected, I think it is a lost cause. That's some very severe damage, and I don't think you'll be able to come back from that.
 

ian field

Joined Oct 27, 2012
6,539
I agree with Ian, unless you're extremely lucky and have a thorough understanding of how everything was originally connected, I think it is a lost cause. That's some very severe damage, and I don't think you'll be able to come back from that.
Looking on the bright side - the gaping hole in the PCB allows much improved convection cooling.
 

GopherT

Joined Nov 23, 2012
8,012
I'm debating on making the effort to fix this, and my big questions are (1) will this goop kill the tips on my iron and desoldering station, and (2) is the damage mostly from fire or capacitor electrolyte?

Long story short; a speaker wire got pinched against the chassis of my car shorting out the amp and releasing copious amounts of magic smoke. The amp sat unused for a couple of years and I just now cracked it open to see the damage, and this is what I found (this picture is AFTER I cleaned it up):

View attachment 95878 View attachment 95879

It's clear the heat from the traces burning burnt right through the PCB and into the bottom of the caps that are circled in the "top" photo, eventually spilling electrolyte all over the PCB. The PCB is now squishy and wet in that black area, despite my efforts to clean it up with denatured alcohol and a tooth brush. I'm thinking I can fix it using wires to replace the traces if I can find a schematic, but will the electrolyte that's absorbed into the PCB continue to cause problems? i.e. is it corrosive? Has anyone dealt with this type of mess before and have any tips on cleanup?
Before you start, look up the price of a used one on ebay and craigslist. It may not be worth your time, effort and supplies to rebuild this one.
 
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