Identifying bad capacitor?

[Taco Bruh]

I accidentally touched 2 wires together on a small amplifier and since then it won't turn on. Im sure it's burnt because of the smell but I decided to open it up anyway just to learn a bit from it.
I took a 2 pictures and as you can see there is a burn mark on the bottom of the board but the thing is, looking at the capacitors, the right 2 lined up have a bulge which I assume is bad yet no burn marks or leaks. Where the burn mark is located is the capacitor right beside the bulged ones which seems to look fine and not leaking. Everything else looks good but I was wondering if the burned one is still good even though it has the burn mark under the board. And if it was possible to bring it back to life. Thanks in advance.

 

[chuckey]

I can not see the burn mark. In the second pic the two capacitors nearest the heat sink look pretty much past it, as their cases have bulged.
Frank

 

[betwixt]

I think you have caused a fault and the capacitors are just in need of replacing due to age/abuse by design. I think it unlikely that the capacitors are stopping it working, the bulging isn't severe and is quite common but still a sign that replacement is advisable. Like Frank, I can't see the burn mark in the photo.

Brian.

 

[candhg124]

over-paste caused short circuit, it is better to replace new ones.

 

[embeddedlover]

It is a common scenario when a capacitor is stressed beyond it's limits, it may go bad.. Go bad in the sense, it may burst or bulge as in your case.. If the capacitors you are mentioning are in the path of amplifier supply, there is a definite chance that they might have gone bad. As you mentioned, capacitors might be away from where the amplifier went bad but there is a chance that capacitors are in the supply path to amplifier.. Have a look at your placement and layout.. Bulging definitely indicates stress and which may cause failure...

 

[Audioguru]

Did you short the output wires of the amplifier that would connect to one speaker?
If the bulging capacitors are in series with each speaker then only one of them would have had over-current when you shorted the wires, not both capacitors unless it is a stereo amplifier that was playing loudly and you shorted a wire from one channel to a wire from the other channel.
Did a fuse blow out in the amplifier?
I think the output transistors or power amplifier IC is destroyed.

 

[Taco Bruh]

Did you short the output wires of the amplifier that would connect to one speaker?
If the bulging capacitors are in series with each speaker then only one of them would have had over-current when you shorted the wires, not both capacitors unless it is a stereo amplifier that was playing loudly and you shorted a wire from one channel to a wire from the other channel.
Did a fuse blow out in the amplifier?
I think the output transistors or power amplifier IC is destroyed.

Yeah, the wires came off the speakers and happened to touch eachother, I saw 2 sparks and that was the end of it. The car smelled like really bad burned rubber. It's an external amp, and there is no fuse in the amp.

 

[Taco Bruh]

Here's a better picture of the burn mark.

 

[FvM]

Yeah, the wires came off the speakers and happened to touch eachother, I saw 2 sparks and that was the end of it. The car smelled like really bad burned rubber. It's an external amp, and there is no fuse in the amp.

Sounds more like shorted output transistors. I'm not sure about an actual "burn" mark below C148. Has the amplifier being repaired before?

 

[Taco Bruh]

Sounds more like shorted output transistors. I'm not sure about an actual "burn" mark below C148. Has the amplifier being repaired before?

Yeah you might be right, after looking at it a bit more, it looks more like the area was coated with some kind of yellow fluid. As far as it being repaired before, I'm not completely sure but I highly doubt it as my family is the first owner of the car that the amp came from.

 

[BradtheRad]

The 'burn' looks like a deposit of smoke particles. There is a chance it spewed from a component on the populated side of the board, and was channeled airborne to the green side.

Did you look inside the enclosure, to see if it has further clues?