# Caesar chorus - no effect



## loves_guitar (Sep 27, 2021)

Hey fine folks,
My once working Caesar chorus (aka Julia) is no longer singing her beautiful ocean song.

Bypass signal works.
Pedal engaged passes signal, but no effects to it. Turning the knobs does nothing. Internal LEDs flash. Rate LED flashes and adjusts with the rate knob.

I wonder if it is the cool audio ICs. Here are the voltages of IC3 and IC4 (voltage from the 1Spot is 9.47v):
1. 0 (ground)
2. 8.76
3. 4.51
4. 8.2
5. 8.76
6. 0 (ground)
7. 4.6
8. 3.4

1. 8.7
2. 0
3. 0 (ground)
4. 8.76
5. 0.3
6. 8.7
7. 2.5 
8. 8.2

I have reflowed all solder joints. 
I'm baffled.


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## carlinb17 (Sep 27, 2021)

It looks like pin 6 of 3207 is not ground it's connected to pin 2 of 3102 according the schematics. Do you have continuity between those two?
your pin 2 on 3207 is connected to pin 4 on the 3102 and that shows a good connection per your numbers above

I can check mine tonight, was there anything that changed prior to it not working?


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## loves_guitar (Sep 27, 2021)

Double checked and I must have measured pin 6 incorrectly. It is connected to pin 2.


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## carlinb17 (Sep 27, 2021)

Here are mine

3207
0
4.2
3.7
8.1
8.7
 4.2
5
5

3102

8.7
4.2
0
4.2
300mv fluctuates
8.3
2.8 fluctuates
8.2

022
4.5 fluctuates
4.3 fluctuates
3-5 fluctuates
0
4.3 fluctuates
3-4 fluctuates
8.7

4558d
4.5
4.5
4.5
0
4.5
4.5
4.5
9

Are you getting any fluctuating numbers?
Was there anything that changed between it working and now not? Aka power surge, wrong adapter plugged in…


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## loves_guitar (Sep 28, 2021)

Thanks for those numbers! I will definitely check those against mine.

It was just a long period of time between using the pedal. I had it on my board and used it for a few gigs. Then sadly I did not use my pedalboard much over the summer. And then when I went to go use it, I heard no chorus effect. Same board. Same isolated power supply.


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## loves_guitar (Dec 8, 2021)

Hey guys. Sorry for resurrecting this thread. But I still have a dead Caesar ("et tu, Brute?!").

I borrowed my friend's Caesar that I built for him at the same time. His pedal works fine. Checked his voltages of 3207 and 3102 against carlinb17's numbers above and they were essentially the same (well within spec). 
But my voltages are still the same as what I posted. I've reflowed all the solder. Checked against the schematic. I am stumped. Not even sure where to look.

Any ideas?


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## fig (Dec 8, 2021)

Audio probe. Connect a wire to the tip lug of the output jack and use the other end to probe along the circuit (with it engaged and something playing through it). Start at the input jack and work your way through the signal path.


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## fig (Dec 8, 2021)

You could _hop_ to key points as well, to narrow down the problem section.


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## Bio77 (Dec 8, 2021)

Can you post all your voltages again?  

Since your LFO indicator light is blinking, your LFO section is working.  If you have a frequency feature on your DMM you can check that the clock is outputting a signal to the BBD at pin 2 and 6 of the 3207.  Set your width to minimum and rate to maximum when you measure or the frequency will drift. 

If you have an audio probe, you should check the output of your 3207, pin 7 and 8.  It could be something wrong with the blend part of the circuit.  It's weird that it died out of the blue, that's usually a lost ground wire or something. 

Just a basic rundown of chorus: You have a clean signal and a delayed signal mixed at the blend pot.  The clock puts out a square wave that runs the BBD to make the delayed signal.  The frequency of the clock is set by a control voltage.  That voltage is modulated by the LFO to modulate the delay time and produce chorusing. If the clock isn't working you won't have a delay signal. 

Good luck.


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## Stickman393 (Dec 11, 2021)

Pin 4 on the 3102 and pin 2 on the 3207 appear to be at +9v, which shouldn't be the case.  I'd peer under the ICs to make sure that there's nothing down there shorting below the chips a loose wire or metal shaving can cause unexpected headaches.

I'd say that it would be a good idea to clean off the board with some 99% ISO as well.  Lots of little patches of flux on there.


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