Aquaboy DLX frequency calibration problem

[AlexB]

I felt like hot shit after building the tourbus without a hitch, but man has this pedal given me a run for my money.

After installing q3 backward, burning out my charge pump and voltage regulator shorting them while checking voltages, and then replacing all three of them I have a somewhat working and set up build.

My BB voltages are where they should be (match with build doc), and the circuit is passing pretty clean delay. My issue is that when the bypass switch is off there is a big high pitched squeal, in order to get rid of that squeal I need to increase the clock frequency all the way to 9.5 kHz, which makes the maximum delay really short.

The pedal also goes into self-oscillation pretty quickly and I basically need to leave the T1 trimmer all/mostly CCW in order to keep the feedback manageable. Are these problems related to each other, is it worth swapping my MN3101 to see if another will give me a better delay time without the squeal or is there something I'm overlooking here.

Also the BBDs are pretty noisy in this build, much less so in my tourbus build. There is a lot of white noise and dithering even when the bypass is on and tails is off. Do you think this is an issue with these particular chips a feature of the circuit topology or did I screw them up when I was testing the pedal with q3 in backward?

PHOTOS: https://imgur.com/a/va0S2g9

Many Thanks,

Alex

[zombie_rock123]

Might not be the greatest idea but have you considered popping out the 1054 and connecting 18 volts to the input of the regulator? If the Tourbus is quiet that'll hopefully give you a simple way to see if that's the problem area.

It could be user error but I've had a couple of issues with 1054s recently and the whine. I've checked the current draw (Thanks Madbean for including on the build docs!) and it's been within tolerance so I've swapped for a 7660S, bridged pins 1&8 and that's cured it on my builds.