Dunlop 535q wah schematic

[g1]

He said with black probe in the centre, he measured 23V so I figure that makes the 23V centre negative.
So polarity is good, would the extra 5V due to being non-regulated be enough to fry something? Maybe, but it was just discharging and unpowered so that voltage would have dropped pretty quick. Maybe a part that had been stressed and just ready to go over the edge?
Or just coincidence. I guess the issue becomes once it is repaired to you try that same power adapter again?

Edit: I see upon replacing the burnt resistor it now works with same supply so this exercise is strictly academic.

[Henry909]

g-one:

It works with batteries. I haven't tried it with that questionable power supply yet. You mentioned the issues I was wondering about; was the extra 5v enough to fry something? was that resistor already stressed? Should I try that power supply again? Am I correct in concluding that if I try that power supply again the worst that could happen is that it will blow the same resistor again?

[Jazz P Bass]

Nothing can be assumed, unfortunately.

If the power supply requirements of the pedal are 18Vdc, then that is what must be met.(within reason)

One of the things about power supplies themselves is that the unloaded voltage is usually higher than the stated output voltage.

So what is the loaded voltage of the PS?

If it drops down to a reasonable voltage then it is o/k to use it.

There is not any one component on the circuit that cannot withstand a slightly higher voltage.

If the polarity is observed & the current requirements are met, power supply input voltages have a leeway that is allowed in the circuit.
(how else would the pedal function with a dropping battery voltage)

[Audiotexan]

He said with black probe in the centre, he measured 23V so I figure that makes the 23V centre negative.
So polarity is good, would the extra 5V due to being non-regulated be enough to fry something? Maybe, but it was just discharging and unpowered so that voltage would have dropped pretty quick.

Ok, missed the polarity part. TY for pointing that one out!

I was assuming that the 17v wall-wort was regulated, since he said

When I touched the plug to the jack I saw a spark..

IME, the only time a wall-wort holds a charge is when it's regulated (My ac adapter for my Ibanez cs-505 does that if I forget to plug it in to the pedal before putting it in the wall). If there's no caps in the wall-wort, then there's no storage. But that's not to say that there couldn't have been potential stored in the pedal itself. But that'd be a new one on me, as I don't recall that ever happening before personally (meaning: I haven't seen a transformer-only (unregulated) wall-wort give that reaction unless polarity is reversed).

As for whether an extra 5v would cook it.. your guess is good as mine man! But I agree with what JPB said, as I can't see a regulated 17v smoking anything. *shrugs* Hard to say 100% without either peeling it open, or putting a load on it though.