SOLVED uberdrive. no signal when switched on. made an audio probe. need some tips

[owlexifry]

first pedal build attempt.
after successfully building a couple tube amps (incl. jcm800 50w / 2204 clone) i thought i’d have a go at pedals, starting with the uberdrive.

i hooked it up exactly as specified in the build docs.

only deviations were:
couldn’t get hold of the specified 2SC732, so i subbed these with 2N3904.
same with 1N916 -> subbed these with 1N4148.
i’m assuming these substitutions should be acceptable, and not cause the circuit to completely fail...

when switched off / bypassed, the signal goes through, no worries.
when switched on, the led lights up, but no signal.....

did some searching. read about using an audio probe.
so i made one (with 100nf cap etc.)
and tested it out last night, starting with the footswitch input terminal - all good.
PCB input - all good.
R2 - all good.
and then i get to C1.
signal at one leg. no signal at the other leg.

from what i’ve read, the idea is that if i’m not getting signal with the probe at a certain point on the signal pathway, then there’s likely a problem at that point?

so with that in mind, i was about to check / re-do the solder joints on C1, but first re-checked it with the probe, and this time with no 9V power supply to the circuit, and signal was passing at both legs of C1.

this has me stumped.
what does this mean?
C1 passes signal with no power, but with power supply it doesn’t.

is the problem somewhere else?
what else should i be looking for?
i’ve checked voltages at various points and this seems to be ok (opamp and transistors are getting positive voltage supply)

any advice would be greatly appreciated. cheers

 

[owlexifry]

(photo taken before i took it out of the chassis to troubleshoot. am now using an ac adaptor plugged into the DC jack when troubleshooting)


(also, i was suspicious that the transistors may not be connecting well in the sockets, so i carefully ‘spot welded’ them in place - this changed nothing)

 

[owlexifry]

so i’ve just realized the pinouts on 2SC732 (ECB) and the 2N3904 (EBC) are different.
i’ve probably connected the transistors incorrectly.

i guess i’ll have to connect the 2N3904 ‘backwards’ with the E twisting back to socket pin 1.


what do people normally do to resolve these sort of pinout mismatches?

 

[JamieJ]

so i’ve just realized the pinouts on 2SC732 (ECB) and the 2N3904 (EBC) are different.
i’ve probably connected the transistors incorrectly.

i guess i’ll have to connect the 2N3904 ‘backwards’ with the E twisting back to socket pin 1.

View attachment 12181
what do people normally do to resolve these sort of pinout mismatches?

You could use a clipped off resistor leg to put into the socket and then tack it to the emitter leg. It would be easier to manipulate the resistor leg rather than the emitter leg.

It is also helpful in the troubleshooting part of the forum to include a picture of your solder joints. Just in case there are any cold joints.

 

[JamieJ]

Have you got anything on the tone pot protecting it from shorting against the PCB? Some cardboard/tape can be useful.

Also did you test the circuit before you put it in the enclosure?

 

[owlexifry]

You could use a clipped off resistor leg to put into the socket and then tack it to the emitter leg. It would be easier to manipulate the resistor leg rather than the emitter leg.

exactly what i just did


and well there you go, now it works.
(on first quick test outside of the chassis)

thanks @JamieJ for your responses

 

[JamieJ]

Glad to hear it @owlexifry

 

[owlexifry]

tested in chassis with guitar and amp.
sounds great!