Aquaboy squeal when bypassed

[atodovax]

Hello everyone. I just finished my aquaboy and sounds fantastic but im getting a high pitch squeal when the pedal is bypassed. I made it with the MOD board and when i engage the MoD with the pedal bypassed the high pitch squeal oscilates at the rate of the MOD. Any suggestions? I set all the trimpots to the center and didnt calibrate them yet

[Neffulator]

Just to add my two cents;
Firstly, I completely missed the fact that one needs to wire the stomp switch to the board and had a hell of a time thinking what am I doing wrong here? Well, after I wired the switch I got the effect "working" and started calibrating it. That should be done prior to any deeper digging, because uncalibrated effect such as the Aquaboy can produce all sorts of noise.
I set the clock to 6,5kHz without problems. When I started to adjust the bias trimmer and connected my audio probe as instructed, there was a distinct squeal. I could eliminate it by turning the clock trimmer all the way up (squeal pitch went up and disappeared, maybe above audible frequency?), but then the delay time was too short to be usable (as a delay). I got fed up with the noise and started putting the board aside and when I removed the test leads of my DMM (which I had used to measure the clock frequency) the noise disappeared! So my DMM was making the Aquaboy board squeal