Novice in need of repair: Can a Broken Ground Fry a Circuit?

Started by digitalzombie, July 19, 2014, 06:00:38 PM

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digitalzombie

I built a fuzz box about 2 years ago, and it worked great then one day there was no signal while engaged. When I cracked it open I noticed the ground wire I had soldered from the power jack to the ground lead of the output jack had come loose at the output jack. I re-soldered both connections and still nothing. Could one of the components on the circuit board have fried from a broken ground connection? I'm only armed with a multi-meter and a very base knowledge of circuit repair. Any advice would be welcome. Please help. Thanks.

edit: in case it's needed, here's a link to the build and a picture of the fairly simple circuit: http://www.ilovefuzz.com/viewtopic.php?f=151&t=11591&start=120

vigilante397

First of all welcome to the forum :)

Second of all a ground wire coming disconnected won't fry anything, especially if it's just the ground wire from the jack. Are you positive that's where the wire came from?

Your link doesn't really give a lot of info on the circuit itself, and you also didn't give a great deal of information about the problem. My best advice would be:

1) double-check the schematic and make sure you soldered the wire back into the proper place and that no other wires have come loose. In my experience wires don't just come loose by themselves after two years, and any stress that can knock one out can easily knock out two.

2) build an audio probe ( http://www.diystompboxes.com/pedals/debug.html ) and see at what point your signal cuts out. This way if there is a fried component you will have a lot easier time finding out which.

If both of these fail...

3) Post the schematic of the circuit (I looked through that link and wasn't able to find one) and pictures of your circuit, making it much easier for forum members to help out ;D
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R.G.

Even better, we've worked out a special set of stuff to do that really, really gets results quickly.

There is a sticky message at the top of the board, titled "Debugging: what to do when it doesn't work". Try that. It gets the members here the info they need to help you fast.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

LucifersTrip

i can't see the actual pics of the build, but if your ground lead disconnected and swung over and hit 9V+, yeah, you could have a blowout
always think outside the box

digitalzombie

Well, this is bizarre. I fixed it, but cause of the root problem is still unknown to me. I was trying to follow the debugging advice with my multi meter, having the power plugged in, pedal engaged, black probe clipped to ground, red probe prodding around at different solder points checking voltage. I noticed the connection point on the IC closest to the on board clipping LED looked like it had no solder on it, so I poked there and the LED lit up! I'm guessing because it was getting a straight voltage? Either way I decided to apply some fresh solder to that hole and viola! Pedal seems to be working fine now. I'm still scratching my head as to how this could have happened though. Like I mentioned before, when it stopped working the only obvious abnormality was the broken off ground wire. Can a faulty ground cause solder to disaggregate? ???

Jdansti

What could have happened was the solder was never on the IC pin, but there was enough of a connection between the pin and pad for it to work. When you lost the ground wire and repaired it, you jostled the connection enough to break the tenuous connection of the pin and pad.
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R.G. Keene: EXPECT there to be errors, and defeat them...