Debugging a Digitech PDS

[sonicblue99]

Okay, so I accidently posted this in schematics and can't figure out how to delete that post, so I reposted it here.  I have a PDS2000 that has no delay.  After going through the forums, I've noticed a fair amount of other people have had this issues with no success at fixing. I was hoping we could start a brain trust to get these pedals up and running.  We all seem to have the same symptoms; leds light up, bypass signal is there, just no wet.  I've tried swapping out the ICs with the spares I have with no luck (everything but the ram chip and two others were replaced.  I used the chips from my working PDS8000 which was identical aside from the Ram and two other chips; counters I believe.)  I'm going to order some replacement chips, but thought we could all troubleshoot this.  Also, I do have schem for the PDS2000 but not the PDS8000 so I'm not sure how close the two are.

[wavley]

Try the compander, that's what went bad in my RDS-900

[Fender3D]

Usually 4007s are prone to fail...
Also check Q11, it shorts NE570's pin 1 to GND, thus shutting wet signal off.