Troubleshooting
Problem
Solution
No delay, no dry audio
Check your wiring and make sure the ADBX is receiving power. Audio probe pins 1 and 7 of IC1 to see where the
dry audio drops out.
Dry audio, but no delay
Audio probe pin7 of IC2 to confirm that the compander is working.
Probe pin7 of IC3 to confirm that the first BBD is receiving signal.
Confirm that you have set the jumpers properly for the BBD set you are using and that pins 1 and 5 of each BBD are
receiving power/ground appropriate to that device.
Max delay is too short
Using your DMM, measure the resistance across lugs 1 and 3 of the Delay pot. If it reads under 1M, considering
replacing it with a pot closer to spec.
Confirm that C33 is actually 100pF (
note ceramics can vary widely so a Mica might be a good choice
). Replace
with a slightly larger cap like 120pF to increase max delay. This may require re-calibration of the delay, however.
Final notes
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You can use 16mm short pin PCB mounted pots mounted underneath the PCB. However, I recommend against this unless you plan on building quite a
few of these. You may find that you need to remove a component or do some work underneath the PCB after you build it to troubleshoot. Having wired
pots instead of PCB mounted ones will make this MUCH easier.
The trimpots are spaced for Bourns 3362P, which are about .25” on a side.
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Last but not least:
DON’T BOX IT UNTIL IT’S READY!
Seriously! Don‘t even dream of trying to put this in an enclosure until you fully calibrate, test and debug
your build. This is a very complicated build and chances are you may run into one small problem or another.
Summary of Contents for ABDX
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