Help requested on a ClinchFX EP-Pre

[StuckItToYa31]

Hi everyone,

I'm trying to figure out what's wrong with this ClinchFX EP-Pre. Being that I've really only built kits with instructions, I'm a little out of my element when it comes to debugging bad wiring in an existing pedal, especially one that uses mini surface-mount components.

The story behind this one is that it was rehoused with a couple of other pedals, and the guy who owned it took it out to resell it to me. It now no longer has output (bypassed or engaged) or power to its LED. I know for sure that the circuit, pot, LED and all of the PCB components were fully functional before the EP-Pre was pulled from the multi-FX creation, so my guess is that he screwed up somewhere reattaching the input, output and power jacks.

No modifications have been done to this center-negative pedal. Being that there is no bypass signal and a loud hum, my guess is the grounding is incorrect. I also don't know how to change the wiring to get power to the PCB and LED.

Any help would be greatly appreciated. Here are some images of my pedal:






EDIT: Here's the only shot I can find of someone else's EP-Pre guts since I can't find a complete schematic:

[thehallofshields]

I'm not familiar with this circuit, but I can't help but notice that your schematic only includes 1 Jfet, while the last board you posted contains a JFET and an Opamp.

Perhaps it is a charge pump to boost 9V to 18V?

[StuckItToYa31]

I should probably remove that schematic. It is completely missing the charge pump and other components, as others have pointed out. Again, it's the actual power connection to the board, the jack wiring, and the grounding that seems to be the issue.

[mth5044]

Any chance of taking it out of the enclosure? Pretty hard to tell from the few angles you posted. You'd have to desolder the power jack, so maybe just leave that part in and take the pots, jack and switch out so you can flip the board over.

[midwayfair]

It's a jet and a charge pump, not an op amp. The charge pump is probably omitted from the schem because it's just a normal lt1054 pump.