Caesar Chorus, both leds working, but ZERO sound at all…

[itstimtime]

Wired her up, and got nothing. Reflowed solder. I don’t have a DMM because the only issue I usually have with builds is forgetting to check the led cathode/anode . D1 & D2 are throbbing. I’m getting signal when it’s bypassed. While turning the internal trim, I get slight “pops” in certain spots. Wondering if those scratches on the underside around IC2 could be the culprit? Haven’t tried swapping out chips because I’ve never had an issue with them I read that a lot while digging through old posts about this build though.

 

[PJS]

You are going to need a multimeter to get this one working. That trim pot needs to be set so that the voltage on the output (pin 2) is 4.5V. Until you have done that there is no point in further troubleshooting.

 

[bhcarpenter]

Agreed that it’s probably the trimmer. There is a VERY small range where the pedal will work properly. A DMM is a surer bet, but you can probably just adjust in small increments while playing until it works.

One nice thing about this project is that it’s obvious whether or not the trimmer is in the right place

 

[Erik S]

Yeah, I remember this being a pain to set, but pretty sure I did it by ear. If you're sweeping the trimmer, that pop may be the sound of going past the spot you need to be at. A looper or some external sound source will make that process a lot more pleasant.

 

[Stickman393]

Zero sound at all, no matter where the blend knob is set?

This pedal has a clean blend, so zero sound indicates that your issue is either on the input or the output.

That would mean somewhere around Q1 or IC2, or even your B10k blend pot.

It looks like you have a pair of scratches across the back of your board, one of which goes across a trace. It's possible that could be grounding out what appears to be your connection between R34 and R36.

Or, the connection could be severed. But being grounded would probably be the more likely scenario, unless an issue exists elsewhere in the circuit.

An ohm meter would help confirm this. Even a cheap harbor freight meter is good enough for checking continuity.

Also: double check where you've landed your input and output jack. Sleeve ground, tip to the switch board.

Looks like your input is hitting the right spot as far as I can tell. Double check that you've got both correct, regardless.

 

[itstimtime]

Zero sound at all, no matter where the blend knob is set?

This pedal has a clean blend, so zero sound indicates that your issue is either on the input or the output.

That would mean somewhere around Q1 or IC2, or even your B10k blend pot.

It looks like you have a pair of scratches across the back of your board, one of which goes across a trace. It's possible that could be grounding out what appears to be your connection between R34 and R36.

Or, the connection could be severed. But being grounded would probably be the more likely scenario, unless an issue exists elsewhere in the circuit.

An ohm meter would help confirm this. Even a cheap harbor freight meter is good enough for checking continuity.

Also: double check where you've landed your input and output jack. Sleeve ground, tip to the switch board.

Looks like your input is hitting the right spot as far as I can tell. Double check that you've got both correct, regardless.

The scratch is what I was thinking it could be. It’s right in the trace of IC2 and the trim

 

[swelchy]

clean up the pcb real good and run a wire from the last solder point to the next on that trace and test..... I busted a trace the other day clipping some leads a bit too hastily and had to run a wire to repair the trace...

 

[itstimtime]

Yeah, I remember this being a pain to set, but pretty sure I did it by ear. If you're sweeping the trimmer, that pop may be the sound of going past the spot you need to be at. A looper or some external sound source will make that process a lot more pleasant.

Wouldn’t I at least be getting some dry signal when the pedal is engaged if it were the trimpot? Hooked it up and was going very slowly, but nothing. Fully CCW got little pops and static. Little more static pop around 1 o’clock but no actual signal when engaged, only bypassed

 

[Bio77]

I've mistakenly mixed up the input and output jacks when testing a pedal out of the box before. Could that have happened?

This circuit has a clean trace all the way to the blend knob, so, you should here something unless there's a problem with that trace. You should make an audio probe and see where the signal is getting blocked.

 

[itstimtime]

I've mistakenly mixed up the input and output jacks when testing a pedal out of the box before. Could that have happened?

This circuit has a clean trace all the way to the blend knob, so, you should here something unless there's a problem with that trace. You should make an audio probe and see where the signal is getting blocked.

Not the jacks…I have signal when pedal is bypassed.

 

[Stickman393]

Wouldn’t I at least be getting some dry signal when the pedal is engaged if it were the trimpot? Hooked it up and was going very slowly, but nothing. Fully CCW got little pops and static. Little more static pop around 1 o’clock but no actual signal when engaged, only bypassed

Your best bet is to leave that guy at noon 'til you get this sorted out.

If it was the BBD bias trim alone, you would definitely be getting a clean signal.

clean up the pcb real good and run a wire from the last solder point to the next on that trace and test..... I busted a trace the other day clipping some leads a bit too hastily and had to run a wire to repair the trace...

This is good advice, but I'd add that you should make sure that it hasn't accidently severed and shorted to the ground plane that's right next to it.

Just do a little scratching motion on either side of the trace within the scratched area. I'll typically use a sheet metal scribe for something like this, but a safety pin or paperclip will work just as well. You just need something with a sharp point to nudge the trace back into place. Shoot, sometimes you can fix a severed trace with a steady hand and a little touch of solder: in that case you wouldn't need a wire.

If I'm correct, a trace shorted to ground between R34 and R36 like I mentioned earlier here looks like it would kill both the dry and the wet signal. Don't quote me on that...I could be mistaken...but it looks to me like that would be th case.