Hi all, thanks in advance for your advice!
Modded a big muff pi. Circuit board states EC-3003 REV_C.
I've done the following,
- replaced the volume pot (like for like, the shaft came out of the pot when removing the knobs!)
- removed D1, D2, D3, D4
- placed 2 on-off-on dpdt switches in the D1/2 and D3/4 point, switching between LED and stock 1N4148 diodes
Result?
- Bypass signal as expected
- Circuit on, LED on, clean sound passed (exactly as bypass)
Checks performed,
- Bypassed sustain and tone pot (signal didn't seem to flow through them properly when tested), when sustain was fully up, the LEDs in the clipping stage were on, flickering. Brightness reduced as sustain rolled down (weird!)
EDIT - these are definitely not working, no connection between any lugs. Bypassed by linking hots together to get above result. New pots now on order.
- checked connections in the vacinity of soldering, all connected as it should be (including new switches). No cold joints discovered (unless you see any...)
- battery and psu used for tests
Points of note,
The modern dc jack is not yet wired in, to avoid the circuit being stuck before it works
D3 and D4 terminals used for a neater solder joint
I'm most curious as the pedal should generate effect regardless on D1-4 being present (like a no diode mod), my understanding then being that nothing can be wrong!
If you can work out what's wrong, please let me know!
Edd


