ZeroPoint Micro squeeeeling

[Bluz]

I have built the ZPM and did the variable mod speed using a 1mC pot.  I socketed R18 so I can try different values of resistors.  When I plug in, there is a squealing noise that varies as I turn the modulation pot.  If I pull the resistor from R18, it stops.  Any ideas of why?  I am confused why I can't get this to work with the variable speed mod.  BTW: the delay will work with or without the R18 in place. Without R18 it works fine, no squealing sound.  Thanks for the help.  Mike

[Bluz]

Ok, so I walked away and left it alone for a while to mow my lawn....I powered up the amp, plugged in the ZPM and now I don't even have any delay.....I've not changed anything.  When I engage the footswitch the led lights up and I have sound but no modulation/delay/etc.....stumped!!!!!  Puuuuzzzzllled!  I checked power to all IC's, etc.  Guess its time for the audio probe.....any ideas? tips or help?  Thanks, Mike.

[Bluz]

I found R16 (1M5) to be broken some how and I replaced it.....sound through the amp with switch on w/o any delay effect....., replaced all IC's, no change. Couldn't find any other problems so far. Any one with any ideas?  Thanks, Mike.

[jimilee]

Sounds like it's time to post some pictures and maybe even some voltages

[Bluz]

I took some voltage reading:

IC 1  (1-8) 4.7 4.7 4.7 9.4 0 4.7 4.7 4.3

IC 2  (1-8) 6.9 6.9 6.9 6.9 6.9 6.9 6.9 6.9
        (9-16) 8.6 8.6 9.4 7.4 9.4 9.4 6.8 4.4

IC3  (1-8) 8.8 4.7 9.4 9.4 0 4.7 4.8 4.8

I have used my audio probe what little time I've had today and haven't any other problems other than R16 being broken.  I've not had time to take pics yet.  Thanks, Mike.