So in case your Marshall JMP-1's memory gets screwed up, if you just want to start from a clean slate or you've just changed the memory back-up battery, here's the Marshall JMP-1 factory reset procedure.
WARNING: Implementing this procedure will permanently delete all user-made changes to any patches.
- Switch off JMP-1 via the power button on the far right.
- Hold down the OD1 button and the CLEAN 1 button.
- While holding down these buttons, switch on the JMP-1.
- Wait a few seconds while the display flashes and then release the OD1 and CLEAN 1 buttons.
I hope this Marshall JMP-1 factory reset procedure helps a few people but if you get seriously stuck, just message me. 🙂
If you want to read more about what I do with JMP-1s, like general service and repair, finding a permanent solution for the skipping data entry knob thing, sorting out the humming transformer issue and offering nice, classy replacement knobs, then please check out some of my other posts:
Apart from service and repair, I sell a few bits 'n' pieces for the Marshall JMP-1 which you may find of interest. Check out my on-line store to find out more.