DOD supra distortion gain problem

[p1_ind]

Any one have a schematic for a DOD supra distortion or a suggestion that would help me fix its problem.

The volume and tone controls seem to work fine but the gain control does not function properly.

With the gain turned all the way down I get a clean signal but turning the gain up even a little bit I get maximum distortion and the rest of the pot travel has no effect only full distortion.

Any help would be greatly helpful.

Adam

[Luke]

hi man,
perhaps the unit is not broken at all- especially if all pots function as they are supposed to. Have you tried a new battery? Also-have you tried just guitar-into effect-into amp? Perhaps one of your leads (guitar cables) is broken- this type of thing happened to me once.
Is this how the unit has always sounded? I mean- did you only just get the effect, and this is how it sounds?
these MAY be the solutions...
Please let us know how you go.
Luke

[p1_ind]

I just got the effect and have had this kind of pedal before and it didn't operate like this.
The battery and cable were tested with another effect with no problem.
And I tested the unit by itself.
Also the bypassed signal is perfectly fine.
And turning down the volume control on the guitar has almost no effect on the gain only the overall volume of the effect.

Adam

[smoguzbenjamin]

Runaway gain Maybe the pot isn't funtioning properly. That would be my first guess.

[p1_ind]

with the pot unsoldered the pot seems to check out OK.
I would like to see either the inside of another pedal or a schematic to see if it doesn't have a wrong component.
Also the opamps have check out OK.

Adam

[smoguzbenjamin]

Can't help you out there I'm afraid, I don't have any DOD pedals. Sorry!

[Luke]

RG Keen has a great article on pots on his website.
I could be wrong, but MAYBE there was a mistake in the factory, and a audio pot was put in place of a linear pot. Rg's article will explain it in far more depth than I can- I would DEFINATELY check it out.
If the pedal was second hand, maybe someone subed the origional pot for this one ?
Hope this helps,
Luke

[Mark Hammer]

The rather crude drawing I have (not a true schematic drawing) suggests that the gain control is simply a variable resistance in the feedback loop of an op-amp in parallel with some diodes.  What this means is that when the resistance goes up so does the gain.  What this also means is that when the wiper of the pot encounters either something obstructing its contact with the resistive element or else is somehow floating above the element, its just like having a HUGE resistance in the feedback loop.

Long story short, a shpritz of contact cleaner stands a pretty darn good chance of restoring proper gain function. If you want to get really fancy, take the pot out, pry the back off, clean up the resistive element and retension the wiper, and reinstall the pot.

[p1_ind]

Does your drawing have a gain pot value the one on the unit is a 500k,
I was wondering if that value is correct because the pot itself tests out OK.

Adam

[Impaler]

I have one and broke it down when I stomped on iot too hard and broke it... All 3 Pots should be 100k LINEAR. At least on the Supra Distortion I have (FX55C).

[p1_ind]

That is what I thought because when I removed the 500k and replaced it with a 100k and the gain adjusted fine.
Thanks for the info.

Adam