King of Tone Clone squeal

[colin.blakely@gmail.com]

Hi all,
I would be grateful for some assistance with an issue I am encountering with my build of the Rullywild Queen of Bone 2 pedal:

One of the two circuits works beautifully, and the other has a high pitched squeal it emits when engaged. I went through with an audio probe to see if I could pinpoint the origin of the issue. The attached schematic is red everywhere that the probe picked up the squeal and green everywhere it didn't. I've already tried swapping the JRC45580 ic's to see if that was the issue, but it didn't fix it. Note, I'm aware it is likely I have an error in my assessment either at R18 or C12 (since they are functionally the same point in the circuit), but I've tried multiple times and still get the same result. Any suggestions of what to try would be greatly appreciated! I'm happy to send photos of the board or an audio file if useful.
thanks,
Colin

[GibsonGM]

Pics would help...

[FSFX]

What charge pump IC are you using? The build docs say ICL7660 or TC1044 or MAX1044. These are the low frequency ones and the schematic shows pin 1 connected to pin 8. That seems to imply that you should be using the ICL7660S or the TC1044S versions where pin 1 is the boost connection to make them run at a higher frequency.
I also note that there is no capacitor on the input of the charge pump. To keep switching noise to a minimum you should always have a capacitor like a 47u or 100u from pin 8, the power input, to ground. This is clearly spelt out in the Maxim applications documentation for these charge pumps.

[idy]

Welcome to the forum.\
Yes, there seems to be an error in your signal tracing. But it would be worthwhile to double check/reflow the solder especially around that 100pf cap. That is there to prevent high frequency oscillation.

Yes, people will want to see your board. They spot the darnedest things.

[colin.blakely@gmail.com]

Thanks all for the quick replies. I've attached pics of the board. It looks like the charge pump is an ICL7660. Both circuits are identical, so if it were an issue with the charge pump, wouldn't I expect to hear the squeal in both? I actually replaced the 100pf capacitor when I first explored the circuit with the audio probe as it seemed to be a likely culprit. No luck. Any additional observations are welcome!
Thanks Again,
Colin

[colin.blakely@gmail.com]

A week of tinkering with the pedal and FSFX had dialed in on the issue with his post. I removed the charge pump altogether (since King of Tone can function on either 9 or 18V) and the squeal is gone. A bit more internet research revealed that according to most, a "non-S" 7660 should never be used in any audio application as it almost always results in squeal. I have no idea why the squeal only showed up on one channel and I'm not sure why the parts list didn't specify 7660S- maybe the author assumed everyone should know that is would have to an S version? At any rate, I will order a new charge pump of the correct variety, but even if the squeal comes back with a different chip, the pedal sounds fantastic at 9V. Either way, problem solved- thanks again for those who chimed in.