Dunlop MC404 CAE Wah Pedal - No Power Help

[Helmholtz]

Main purpose should be reverse polarity protection (see link I posted above) as the pnp transistor only conducts if its emitter is more positive than its other electrodes.

From your measurements Q3 seems to be open, so replace it.

[misterc57]

I am not equipped or skilled to replace SMD, especially this small in a tight configuration.

Wonder if I can place a jumper from the 9V supply to the anode of D4, would this not be creating a reverse polarity protection?

[Helmholtz]

I am not equipped or skilled to replace SMD, especially this small in a tight configuration.

Doesn't require special equipment. Just a pointed soldering tip.

Wonder if I can place a jumper from the 9V supply to the anode of D4, would this not be creating a reverse polarity protection

That should work though probably not as reliably as original. Supply voltage will be lowered by 0.5V.
Nevertheless I would remove the transistor using solder wick. Also gives a chance to test it.

[misterc57]

Pedal is working now. Ran two jumpers. One from the PS ring to the anode of D4, one from the cathode of D4 to C13.

Thank you Hemloltz for your help and guidance!

MarkO

[Helmholtz]

Glad I could help.

[Mars Amp Repair]

Hello,
I had one of these that was a prototype so didn't match the production one exactly where the voltages were also off as you're experiencing. Turns out the transistor that actually does the power switching triggered by the input jack was bad.
On this board it was screened as Q3. As I recall it is just to the right (closer to the narrow side of the pedal) of the external DC input jack (component side). It is a PNP gen purpose SMD transistor. I don't know the number as I had to steal one from a scrap board.
Hope that helps.
Glen