Yet another Caesar Chorus problem

brightlight

Active member
I've read through every thread on the Caesar I could find and this specific issue never seemed to get mentioned to this degree so I'll ask. Also, I know posting pics of the board is standard procedure, but I'm at work right now so I'll have to do that later.

I was hoping that maybe the symptom could be a dead give away for someone here. My rate LED works, the 2 internal red LEDs flash as well, I get sound in bypass, I get sound when active, but only in a few spots on the trimmer. Just wanted to get the good parts out of the way.

Now, when I dial in the trimmer I get no sound on either extreme end, which seems normal. As I approach the center I get anywhere from fuzz to clean, yet non-chorusing signal. When I get real close to the center the signal gets really loud and it sounds like a police siren going off in my house, like insanely high pitched whistling. Does this sound common or familiar at all?

My TL022 and 4558 are from Tayda, my 3102 and 3207 are CoolAudios that I bought from @StompBoxParts so those should be good. I bought 2 sets, swapping them out is on my to-do list when I get home.

Thanks, all! Hopefully this is a quickie, again sorry for lack of pictures at the moment
 
Not sure about the police siren, that's a new one to me, for a chorus, common on a flange. The rate indicator light working means your LFO is likely good. Passing signal when you turn the trim means the delay line is likely working. Does the signal sound like vibrato?

Not having any sound at the extremes could mean you have a problem with your clean path. Although, this is CE-2 based and the bias and ref V are linked. You should audio probe the components along the clean trace (starting after C5) and figure out if you have the clean signal all the way through. If you do, audio probe the out of the delay chip and see if that's the problem. Set the bias trim to where you were hearing the cleanest signal.
 
Not sure about the police siren, that's a new one to me, for a chorus, common on a flange. The rate indicator light working means your LFO is likely good. Passing signal when you turn the trim means the delay line is likely working. Does the signal sound like vibrato?

Not having any sound at the extremes could mean you have a problem with your clean path. Although, this is CE-2 based and the bias and ref V are linked. You should audio probe the components along the clean trace (starting after C5) and figure out if you have the clean signal all the way through. If you do, audio probe the out of the delay chip and see if that's the problem. Set the bias trim to where you were hearing the cleanest signal.
I'll look into these things, thank you!

I spent all afternoon trouble shooting as many things as possible that don't require pulling the board out of the enclosure so I didn't have time to make an account on a photo hosting site to be able to post pictures here. But I do have a YT account and made a quick video of the noise I'm referring to. If the foot switch looks funny it's because I was working on something with it and I had it hanging instead of fastened.

WARNING: check your volume, the sound gets very loud!
 
is the video with no signal going through the pedal? I don't hear any clean signal. If that is the case, does the sci-fi raygun sound change when the clean signal is playing?
 
is the video with no signal going through the pedal? I don't hear any clean signal. If that is the case, does the sci-fi raygun sound change when the clean signal is playing?
I'm occasionally strumming the guitar. You hear the clean bypass signal right at the beginning and then I turn the effect on. I strum the guitar every few seconds but you either hear nothing, fuzz, or the crazy squealy siren
 
so there is definitely a problem in your clean channel. and that may be causing what you are getting in the delay. removing the board from the enclosure for troubleshooting will also let you test it then to see if it works when uncased. if it does not, then visual inspection of good pictures plus an audio probe are your best approaches to isolate and fix the issue(s).
 
so there is definitely a problem in your clean channel. and that may be causing what you are getting in the delay. removing the board from the enclosure for troubleshooting will also let you test it then to see if it works when uncased. if it does not, then visual inspection of good pictures plus an audio probe are your best approaches to isolate and fix the issue(s).
Ok thank you, it's a start. I was hoping to avoid uncasing the board, but I really want this thing to work. I've already decided going forward I'll be building Sea Horses due to parts availability, but I refuse to let this one go to the graveyard lol
 
I decided to lay this one to rest. I tried all the trouble shooting I knew how. I checked every component value and they were good, I went over both sides of the PCB with a magnifying glass and light 3 times. I ended up finding one suspicious contact between one of the red LEDs and the waveform switch. After I got definite airspace between them only 1 of the internal LEDs worked and it was on constantly instead of flickering. I thought maybe I fried the 10u between the LEDs so I swapped that, no change. Swapped the LED itself, no change. All of this also caused the rate LED to be on constantly instead of in time with the rate of the effect and only on one of the switch positions, nothing in the other position. I tried what I could and since I've developed a preference for the Sea Horse anyway I'm gonna let this one go. I have about 8 other builds waiting in my parts box and don't want to keep them waiting.

Thanks for the help and advice everyone! I did learn quite a bit, that's worth it to me.
 
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