SOLVED Caesar Chorus Biasing

[VanWhy]

I'm having a hell of a time getting the Caeser Chorus biased. Which I think(?) Is the issue. I did go with a 100k trimpot since I didn't have a 50k. Not sure if that already is an issue.
The dry signal comes through fine, when I turn the blend know to the right the signal gets killed. I've tried twisting that damn trimpot back and forth as slow as possible many times but not finding a 'sweet spot'. I get to a position where it kills the dry signal. But not getting any Chorus at all. Everything thing looks socketed properly. I removed and reseated all IC's. Double checked they were in the right spots. I don't have any more of the clock ICs to swap atm. What's the deal?

 

[Mcknib]

A 100K trimmer would just be harder to fine tune so to speak you can set it to 50K between lugs 2 and 3 then as you turn CW resistance will decrease giving you the correct resistance range to sweep through

Are you getting signal into pin 3 and out at 7/ 8 on the 3207

 

[VanWhy]

Are you getting signal into pin 3 and out at 7/ 8 on the 323207

How do I measure that on my DMM?

 

[Mcknib]

Use an audio probe you'll be able to check inputs and outputs of active devices much quicker

Should be clean in at pin 3 and wet out at 7/8

 

[KR Sound]

I do remember when I built it that there was a real small range where that sweet spot was. Might be harder to find with a 100

 

[Barry]

I do remember when I built it that there was a real small range where that sweet spot was. Might be harder to find with a 100

Ditto

 

[VanWhy]

Update I'm not getting anything when probing the IC's. Not sure if it's the sockets or the actual ICs. I'm going to order some more and try swapping.

 

[Locrian99]

If you aren’t getting any signal at the ic then the issue isn’t the ic. You should have something at pin 3 like @Mcknib mentioned.

 

[Locrian99]

If you get dry signal to pass through but no audio at pin 3 of the 3207 then I would think your issue is somewhere in here.

I would myself verify you have signal at pin 1 of ic2 (I do t think you’d have any dry signal if you didn’t) then I would check at the 5088, work back from there if you don’t have audio.

Could be a bad connection in the socket, I hate those transistor sockets. .

 

[VanWhy]

If you get dry signal to pass through but no audio at pin 3 of the 3207 then I would think your issue is somewhere in here.
View attachment 56162
I would myself verify you have signal at pin 1 of ic2 (I do t think you’d have any dry signal if you didn’t) then I would check at the 5088, work back from there if you don’t have audio.

Could be a bad connection in the socket, I hate those transistor sockets. .

So I I'm getting signal all the way up to IC3. Seems like the last place I get signal is the R24, 4K7. Nothing on any of the pins of IC3. Then a weird squealing from one of the pins in IC4. 5 I think?
Getting signal from the 4558. Probed the transistors and resistors up to that point and all passes.
By the way this is all with the blend know on dry.
The path is IC1 to IC3 to IC4, right? Didn't check IC2 but looks later in the path. Don't know what all this means tho

 

[Mcknib]

From what you've said dry signal appears OK you can also check dry at blend pot lug 3 and wet at lug 1

IC1s your LFO you shouldn't get audio through that does your led D LFO pulse at different speeds with the rate pot

I'd also check for audio at pin 3 with IC3 out of socket

 

[djmiyta]

I'm having a hell of a time getting the Caeser Chorus biased. Which I think(?) Is the issue. I did go with a 100k trimpot since I didn't have a 50k. Not sure if that already is an issue.
The dry signal comes through fine, when I turn the blend know to the right the signal gets killed. I've tried twisting that damn trimpot back and forth as slow as possible many times but not finding a 'sweet spot'. I get to a position where it kills the dry signal. But not getting any Chorus at all. Everything thing looks socketed properly. I removed and reseated all IC's. Double checked they were in the right spots. I don't have any more of the clock ICs to swap atm. What's the deal?

Ya know for me I've used a couple of different trimmers and depending what and which kind a trimmer you got that " sweet spot" you're looking for can be a micromillicentmetermicron of a movement. I forget which pedal it was but I had a hell of A time getting it right as in putting it down for a week or 2 giving it another shot after about 6-7 months I said fuck and got some decent bourns trimmers replaced them all and had it biased up in 1/2 hr. I think it was my Dr Boogie pedal. Just a random thought I thought i'd throw out there.

 

[VanWhy]

Coming back to this one...

From what you've said dry signal appears OK you can also check dry at blend pot lug 3 and wet at lug 1

I get a signal with blend knob all the way to dry on lug 3. Still nothing on lug 1

IC1s your LFO you shouldn't get audio through that does your led D LFO pulse at different speeds with the rate pot

I am getting signal from pin 1 or 2 (forgot) on IC1. The LED does pulse different speeds with the rate pot

I'd also check for audio at pin 3 with IC3 out of socket

I checked IC3 pin 2 with no IC in and still no signal.

I wonder if it could be the socket for IC3? I can try to unsolder but I'm terrified to pull a trace pad. I don't have a proper desolder gun yet.

BTW thanks for helping me troubleshoot.

 

[VanWhy]

Happy Days are here again. I was troubleshooting another pedal and getting frustrated so I put it down. I wanted to get a win for the night to feel better so I broke this one back out. I got more ICs last week so I thought of trying that out and of course that didn't work. I gave it 1 last chance, took it out of the enclosure to give it a triple check and guess what? I noticed I missed legs 1,2,3 of IC3.... Son of a bitch. Soldered them up and now we have a real deal Ceaser Chorus pedal on our hands. Thanks everyone.

 

[PJS]

That is a very silly mistake to make. However, I have made it several times so no criticism ;-)

 

[VanWhy]

That is a very silly mistake to make. However, I have made it several times so no criticism ;-)

Yeah it's pretty embarrassing but at the same time it's sometimes how I learn