Any idea why a pedal would suddenly go nuts?

[LaceSensor]

Hi

I built a pedal for myself, it worked great, then I decide to sell it.
It was based on the MI audio crunch box / Guitar PCB crunch which of themselves are Op Amp based diode clipped "Marshall in a box" effects
Guy has written to me saying he cant use it anymore as it simply produces a high pitch sqealing sound at any volume; nothing else has changed in his setup or powering etc.

Any thoughts for things for him to check before he posts it back?

thanks

Ian

[Cortexturizer]

Aks him whether or not he had used a laptop power supply. I've had a case just like that and the guy was actually nuts...haha.

On a more serious note, I've had a couple of cases occur where cat hair had been the culprit. This is also the reason why I meticulously rock before I box. I love my cat, but pedal-wise, it is nothing but problems

[Govmnt_Lacky]

I suspect you are not getting the whole story. Sounds like a wrong power supply issue to me 

[gjcamann]

If it isn't a bad PS, or damage from an incorrect PS, then it's either a problem with the wiring or a component failure. I assume you work is good, so perhaps it is a component failure - likely a cap or IC.

Request some gut shots to verify wiring - and that he hasn't tried to screw with the pedal.

I'd send him 2 new IC's and see if he can fix it himself.

Does the volume and presence knob work?

[raulduke]

A good gut-shot might help to show any obvious issues (disconnected wires, shorts etc.).

Also get him to take a photo of the PSU he is using and have a look.

From my experience some people will just stick whatever PSU they have knocking around into a pedal and expect it to work.

[lars]

It could also be how he set up his signal chain. Recently I tried a configuration where used a splitter to send my input signal to two different pedals and combined the signal back at the amp. It worked fine if you just used one pedal at a time, but when you turned both on at once, it squealed like crazy.

[GermanCdn]

Gremlins.

[LaceSensor]

waiting for feedbck from the fellow

he isnt the kind of person to go taking stuff apart, and he had everything on a pedal board set up, so I doubt he ran it independantly with some crazy PSU.... but it can happen I guess.

Worst case is I have to replace some parts or rewire something.

[kothoma]

So if you think it's an honest fellow then don't waste any time. Fixing this pedal sells your next pedal.

[LaceSensor]

its not a problem with just this pedal now, apparentyly

he has tried with a boss psu, as well as his DC brick (8 x 9v supply) as well as testing his other overdrive and fuzz pedals, and they are all causing a squealing sound through his amp.

ill help him figure out what it is! but its clearly not just my pedal that is faulty.

[juansolo]

Hi

I built a pedal for myself, it worked great, then I decide to sell it.
It was based on the MI audio crunch box / Guitar PCB crunch which of themselves are Op Amp based diode clipped "Marshall in a box" effects
Guy has written to me saying he cant use it anymore as it simply produces a high pitch sqealing sound at any volume; nothing else has changed in his setup or powering etc.

Any thoughts for things for him to check before he posts it back?

thanks

Ian

9 times out of 10 it's the PSU they're using. Had it happen a few times with people plugging my stuff into shat PSUs.

Saying that, I have made stuff that's seemingly gone bonkers. They were the first multi's I let into the wild and they had multiple clocks in them... Doesn't always manifest in testing.

Also had a bad trimmer cause fun and games...

Damaged PSU socket too...

...and the old favourite of them sticking an AC or 18v PSU into a 9vDC pedal....

[LaceSensor]

apparently it does it with any psu he has

further chat says that

1 - the amp will sqeal like this on the gain channel (marshall TSL)
2 - doesnt squeal on the clean channel, or with other pedals (delay, phaser, compressor) using same PSUs etc
3 - will squeal with any gain pedal added, clean channel included

therefore, I am recommending he checks for microphonic tubes as the first port of call...

thanks for all info

[Shrtyska9]

Could also be a microphonic cable. Have him plug directly into the amp and see if it still happens if it does then check the tubes.

Richard

[juansolo]

...or the pedal could be female...

[kothoma]

...or the pedal could be female...

Oui, bien sûr, vraiment, c'est la pédale!