Bone Machine not working on germanium side

[Getomonk]

Hi

I have a Trombetta Bone Machine on my board that built a while ago. I was just adding a new power supply (trex Fuel Tank) and when plugging it in the board switched off except for a weird clicking noise. It turned out the to be problem with the power lead connected to the Bone Machine. After replacing the lead the germanium side of the fuzz doesn't work. If I switch the toggle to engage the silicon side the pedal works as expected.

I have measured the voltages on the germanium and get 0 volts on all three pins, so I assume the power malfunction has killed the transistor?

Does anyone know what might have happened? The pedal has a polarity protection diode. Also I need to order new transistors from Germany, so I would like to know if anything else might have been damaged?

Sorry bit of a noob when it comes to troubleshooting.

Cheers
MortenP

[Travis]

I'm looking at the schematic and I don't see a switch that selects between Ge/Si

My guess would be that either the 2K or 39K resistor connected to the "mood" switch was burned out from the power malfunction

Edit: oops, didn't see there was a second version added with that switch. Yeah, sounds like the transistor may have gotten damaged unfortunately. Maybe try another 2N3906 in that position to see if it works, then you will know if the problem is just the Ge transistor

[Getomonk]

Hey Travis

Thanks for your reply. I don't see any burnt resistors on the board and I assume that would cause the whole pedal to stop working? Good idea with the 3906, I'll give it a shot.

Best Morten

[Travis]

Yes scratch that suggestion about the resistor I hadn't noticed there was a second version with the Si/Ge switch.

Good luck with the other suggestion. Let me know if the problem persists