Vox 847 Problem

[bluesman94]

I recently purchased a VOX 847 Wah Pedal, and It has worked fine for about a week...

BUT earlier today it died. It buzzes (The loud, constant kind of buzz) when I plug in the cable (the one from the amp to the pedal). Both the cables work fine when you plug them directly from the amp to the guitar

Now comes the interesting bit (interesting to me anyway...) Try and stay with me here... If you plug the cable from the amplifier into the input on the pedal that would normally go to the guitar, and plug the cable from the output of the pedal that would normally go to the amplifier into the guitar, it will bypass the signal, but when you stomp on the pedal to turn it on, it becomes completely silent.

I really hope someone can help me out here. Maybe someone here has repaired something like this before.

[curtisa]

First thing I'd suggest doing is opening the pedal up and looking for any wires that have broken free - maybe the battery clip, the input/output sockets, the footswitch, or the pots. I've had Behringer mixers that had really bad hum that was tracked down to a broken wire on the power supply connector.

[Thoughtless 7]

You're not using a battery are you? If so check that as well.

Does it buzz when its plugged in correctly but the wah is turned off?

[bluesman94]

You're not using a battery are you? If so check that as well.

Does it buzz when its plugged in correctly but the wah is turned off?

Yes, it buzzes when the wah is off, and the when it is on. And for some reason, you can control the "tone" of the buzz both ways. It isn't the power supply, because I can use the same setup to power a distortion pedal.

[Thoughtless 7]

I'd take off the base plate and just have a look around and see if anything has come loose. Are you any good with the soldering iron cos you might need to do a repair job.

Check the footswitch and the input/output jacks also the powersupply jack. If you are confident you could take the circuit board out and see if anything looks suspicious.

[Paul Marossy]

Assuming you have a newer wah pedal, it may be possible that the soldering on the connection(s) from the jacks to the PCB have been compromised on the input jack. That is the first thing I would check for.

[bluesman94]

what does a bad connection look like? All the wires are attached to something.

[curtisa]

Anything that looks like it's about to fall off - wiggle the wires and see if they stay put (looks can be deceiving) - or a solder joint that has a fractured look, or dry crispy look around its edges.

[Paul Marossy]

Yeah, look for solder joints that look "fractured".

[bluesman94]

i think i found something, i'll tell you guys how the repair goes.

[bluesman94]

nope, guess not. I tracked down my old voltmeter and that connection works fine. As do all the other wires. So it must be a component, right?

[Paul Marossy]

Could maybe be a fried transistor. I would use an audio probe to trace the signal thru to where it dies - that's most likely where your problem will be.

http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf

[bluesman94]

It's not a transistor. Everything seems fine when I check the connections with the multimeter, but when I plug in it just buzzes! Do you think it could be a short?

[Paul Marossy]

Hmm... maybe it's the bypass switch?