Line 6 DL-4 - No sound when effect is engaged (bypass works)

[beedoola]

I just traded a guy another pedal for this DL-4. Is in great shape and worked fine yesterday and today but then when I went to engage the effect again I got no sound. I did the factory reset and reseated (removed and reinstalled) the EPROM chip (sometimes that remedies some of the DL-4 issues) but neither worked.

I've repaired non-powering DL-4s in the past but this doesn't seem to be a power section issues as the pedal powers up fine and all the functions seem to work properly.

Any ideas on how to troubleshoot this?

some links

http://lazyecology.web.fc2.com/rever...line6_dl4.html

[Jazz P Bass]

Make sure the power supply voltages are proper.
+5Vdc & +3.3Vdc.

If that block diagram can be trusted, I would jump right to the ADAC.
Look up the datasheet.
Do you have signal in?
Do you have signal out?

[beedoola]

Thanks. I had assumed the PS voltages were fine because the unit powers up but after reading the voltages in the PS section I found the voltages were not right coming out of a voltage doubler (U20). Was only getting near 2v. I removed it and ordered a new one. I hope that solves the issue.