Caesar Chorus, no osc light or wet sound

[finegritmusic]

Built the Caesar Chorus and it has sound pass when pedal is not engaged, and also dry sound through the pedal when engaged. However there is no chorus sound, and oscillating LED is blank. When mix is turned all the way up there is no sound at all.

Wonder if someone could help with some advice. Thanks!

 

[synthesiserror]

Is IC1 a TL022? I cant tell if it's unmarked or if the light is just hitting it wrong.

 

[DGWVI]

Is IC1 a TL022? I cant tell if it's unmarked or if the light is just hitting it wrong.

Was just gonna ask this.
Otherwise, there are a few joints that look like they could be hit with some fresh solder, particularly those for the electrolytics.
There also appears to be some stray strands coming off of the footswitch wires

 

[synthesiserror]

Also, there's something weird going on with R27. Unless you sacrificed a smurf to the tone gods, it looks melted to me. Possibly also a stray wire strand causing a short just to the north of R27.

 

[Sturdag Lagernathy]

Blue tack residue perhaps?

 

[music6000]

What is this stain/ burn? :
This spot circled is R12-22K, the Trace goes from that resistor pad to the centre pad 2 of the Shape Switch.
Check to se if you have Continuity ??

 

[finegritmusic]

Is IC1 a TL022? I cant tell if it's unmarked or if the light is just hitting it wrong.

Yes it is the TL022

 

[finegritmusic]

Also, there's something weird going on with R27. Unless you sacrificed a smurf to the tone gods, it looks melted to me. Possibly also a stray wire strand causing a short just to the north of R27.
View attachment 62729

This is just a little leftover blue tack I use to hold the ic sockets. isn't in signal path

 

[finegritmusic]

What is this stain/ burn? :
This spot circled is R12-22K, the Trace goes from that resistor pad to the centre pad 2 of the Shape Switch.
Check to se if you have Continuity ??

View attachment 62742

Good eye, def looks alarming in the picture. Turns out to just be a little speck of tobacco.

 

[finegritmusic]

Was just gonna ask this.
Otherwise, there are a few joints that look like they could be hit with some fresh solder, particularly those for the electrolytics.
There also appears to be some stray strands coming off of the footswitch wires

I'll try to hit the electrolytics again maybe. Did a one over and all connections seemed solid. Wire was a little thicker than I wanted to use so there are a few tiny strays but they don't make connection to anything. Will definitely clean that up for the final, thanks.

 

[DGWVI]

I'll try to hit the electrolytics again maybe. Did a one over and all connections seemed solid. Wire was a little thicker than I wanted to use so there are a few tiny strays but they don't make connection to anything. Will definitely clean that up for the final, thanks.

You wanna make sure there's no spiky or dull looking joints.
If I get a chance tomorrow, I'll take a better look at your pics

 

[finegritmusic]

You wanna make sure there's no spiky or dull looking joints.
If I get a chance tomorrow, I'll take a better look at your pics

I hear you, I'll do another once over on them, but I did remelt any sus ones before this pic. I've done around 30-50 pedals from pcbs on here and solder joints haven't been a problem as of yet. Much appreciated, but do think something else is may be at fault here. I did scratch the board a little at the bottom near the footswitch. Could this be at fault?

 

[DGWVI]

I hear you, I'll do another once over on them, but I did remelt any sus ones before this pic. I've done around 30-50 pedals from pcbs on here and solder joints haven't been a problem as of yet. Much appreciated, but do think something else is may be at fault here. I did scratch the board a little at the bottom near the footswitch. Could this be at fault?

Scratches can definitely cause issues- you'll wanna check to make sure there's still continuity on either side of the scratch, and also ensure that there's nothing (copper flakes, solder) shorting against anything it shouldn't.

 

[KR Sound]

Any chance your Blend pot is bunk?

When mix is turned all the way up there is no sound at all.

 

[chris.knudson]

Can you check to make sure you have the polarity correct on the LEDs? Since they aren't lighting up, I'd start there.

 

[finegritmusic]

Can you check to make sure you have the polarity correct on the LEDs? Since they aren't lighting up, I'd start there.

Just checked and all 4 are good, although the one for osc is very dim when lit. Could this cause issue in the circuit performance, or just a lower quality? Also for note the on/off LED has been functioning fine the whole time

 

[finegritmusic]

Any chance your Blend pot is bunk?

Seems ok according to my cheapo meter

 

[chris.knudson]

Just checked and all 4 are good, although the one for osc is very dim when lit. Could this cause issue in the circuit performance, or just a lower quality? Also for note the on/off LED has been functioning fine the whole time

If the polarity is correct, that probably isn't the problem. I was just thinking that the LEDs are in the wet part of the circuit and that if the dry part was working fine, then a reversed polarity on one of those diodes might be the culprit. I haven't looked at the schematic yet, but I'm assuming that your problem is somewhere in the part of the circuit that produces the oscillation.

Also, if the dry signal is fine and the wet signal isn't getting through, that's an indication that your blend pot is working fine.

 

[Bio77]

Do you have an audio probe? Do you have a frequency setting on your DMM?

No audio at 100%wet on the blend pot means you aren't getting delayed signal. That would happen is the clock isn't working. You can check that by probing pin 2 or 6 of the BBD with your DMM. You should measure ~30kHz. If the clock is working, use your audio probe to test the output of the BBD at pins 7 or 8. If you aren't getting audio there check your bias trim, first.

The LFO indicator light not working indicates a problem with the LFO. However, that wouldn't keep the delay signal from passing. So you might have two problems. Why don't you measure the voltages on all the chips and post them. This might help identify the problem.

 

[synthesiserror]

Yes it is the TL022

I would try swapping this IC with a known good TL072.