Weird Fuzz Face noise

[Drewmeyer]

So I just sold a fuzz face on ebay and, of course, it arrives with an issue. The buyer claims that the pedal makes a lot of scratchy noise and drop out as he rides the volume on his guitar. Now I am pretty sure this problem did not exist before I sent it out, so I assume it must have occurred during shipping. He hasn't had a chance to take pictures of the guts of the pedal, and I hope I can pick out the problem from those, but I was curious if anyone had an idea of what might be wrong. Thanks!

[GibsonGM]

PNP, NPN?  Altho most are very similar.  Just thinking about grounds here...DIY pedal, or bought?

What the guy is reporting is symptomatic of DC on the volume pot.  This can occur when an input cap fails, and allows bias voltage to flow back into the axe.   Trouble is...the FF generally isn't the kind of circuit that's wired up with a DC bias on the transistor base!!!  I spose you could get a bit from Q2, thru the base...mayyyybe enough for scratch if the input cap is toast.   Do you have the original schema you used (if DIY)?    Another cause could be an intermittent input jack. Heck, they guy's CORD could even be bad....

I'm starting to the think the problem could also be with the pot on the guy's guitar.  Active pickups, and a leaky cap somewhere in there?    Most effects don't 'react' when you turn the guitar down (sound different, yes, maybe even cut out at some point, but not like something is 'broken').  Maybe his guitar ground is malfunctioning, and not playing nicely with the PNP FF (if it's positive ground). 

Anyway, you know the rules...you probably have to take it back /   If you do, replace your input cap for the heck of it, if it makes any noises on YOUR guitar.   

[Drewmeyer]

PNP, NPN?  Altho most are very similar.  Just thinking about grounds here...DIY pedal, or bought?

What the guy is reporting is symptomatic of DC on the volume pot.  This can occur when an input cap fails, and allows bias voltage to flow back into the axe.   Trouble is...the FF generally isn't the kind of circuit that's wired up with a DC bias on the transistor base!!!  I spose you could get a bit from Q2, thru the base...mayyyybe enough for scratch if the input cap is toast.   Do you have the original schema you used (if DIY)?    Another cause could be an intermittent input jack. Heck, they guy's CORD could even be bad....

I'm starting to the think the problem could also be with the pot on the guy's guitar.  Active pickups, and a leaky cap somewhere in there?    Most effects don't 'react' when you turn the guitar down (sound different, yes, maybe even cut out at some point, but not like something is 'broken').  Maybe his guitar ground is malfunctioning, and not playing nicely with the PNP FF (if it's positive ground). 

Anyway, you know the rules...you probably have to take it back /   If you do, replace your input cap for the heck of it, if it makes any noises on YOUR guitar.   

Oh silly me, I forgot lots of information. It's a NPN silicon built off this guy's kit: http://www.pigeonfx.com/layoutff.html. The buyer of my pedal claims it is not the guitar because he used a variety of guitars nor the cord because he's tries with multiple cords. I think what you said about DC on the volume pot is probably the solution. What do you think I could try as a fix for this? Replace the input cap?

[GGBB]

What do you think I could try as a fix for this? Replace the input cap?

Yes.  Did you orient the caps according to the NPN diagram or according to the markings on the PCB?  The PCB markings are for the PNP version - caps need to be reversed for NPN.  That would explain them failing.