Digitech WH-1 problem

[stevenrb718]

Anybody have experience with dead WH-1s? I have one that doesn't function or light the LED. The photocoupler LED inside the pedal does light up, and I believe I'm getting the proper voltages from the 2 voltage regulators (U24 gets insanely hot but it is mounted to the shell). I've tried re-seating the socketed chips and looked around the board but nothing is jumping out to me.

[Jazz P Bass]

Schematic?

[The Dude]

^^^^^^Yes, that. There are several versions, so we need to see the schematic for the version you are working on.

[alexradium]

check the dsp processor if it gets hot,i had to replace one since the 3,3V regulator was very hot

[Mick Bailey]

What are the output voltages of the regulators? Low 3.3v can be a problem.

[stevenrb718]

I can't find a schematic through my searches. My model is a rev F if that helps. I'm getting a solid 5V from the one regulator and a -7.9V from the other. I believe the -8V is an appropriate value.

[g1]

What is the number on the -8V regulator? What are the voltages on the other pins? Could be -8V in and should be -5V out?

[g1]

See if the first 3 pages of these schematics is of any help: https://music-electronics-forum.com/...7&d=1530152707

[stevenrb718]

What is the number on the -8V regulator? What are the voltages on the other pins? Could be -8V in and should be -5V out?

It's a 7908 so the -8V is expected.

[Mick Bailey]

I was mistaken in thinking these had a 3.3v supply - this must only be in the later versions.

[stevenrb718]

See if the first 3 pages of these schematics is of any help: https://music-electronics-forum.com/...p;d=1530152707

I can't really make out a lot of the schematic, but I seem to have proper voltages in several places. The effect indicator LED doesn't cycle, but also has power. Is there some kind of a mute circuit that's locked up? Or could the issue be with the CMOS controller?

[g1]

I would look for a crystal and see if you can determine whether the clock is running. Around that era it was fairly common to find bad crystals as they didn't seem to be able to take the kind of abuse (dropping, etc.) that modern ones can.
A datasheet for the CPU should also be helpful as far as where the clock signals should be.

[stevenrb718]

I would look for a crystal and see if you can determine whether the clock is running. Around that era it was fairly common to find bad crystals as they didn't seem to be able to take the kind of abuse (dropping, etc.) that modern ones can.
A datasheet for the CPU should also be helpful as far as where the clock signals should be.

The crystal is working and from what I can make out on the schematic, I have clocks at several locations.

[g1]

Any hot IC's or other components?

[stevenrb718]

The mentioned voltage regulator gets piping hot at 200 F, but it is mounted to the shell so I guess that's alright. It's putting out the correct voltage. The only things even showing much of a heat signature are the ROMs at about 110 F.