Very good question. The printed and online material I have seen so far is way too basic and vague. I would like to see a schematic that includes values, etc. Or a narrative discussion of the circuits of the amp. I found these somewhere (can't remember where). Hope they're helpful but I have no idea...

Hi Guys,

I've taken the list of presets offered above and put it into a spreadsheet. I hope this is of use to someone. Please let me know if you find any errors.

Enjoy....

I do not believe there is any kind of troubleshooting guide for the JMD available, but some of us here have experience working on them and would be glad to help. If your amp is losing all front panel lights and sound, but the power tube filaments are still illuminated, it is likely the +12V digital...

Hi Guys, I have a JMD1 100w head. On 2 occations it has produced a very loud POP and gone completely dead (no lights, sound, etc.). I turn the power switches off and then some time later I'll turn it back on and everything seems fine. What would be a good method for isolating the cause? Is there a t...

Hi guys,

Does anyone know if Marshall publishes a maintenance manual for the JMD1 and how to acquire one? I have a 100w head and would like to be able to maintain it using information published by the manufacturer.

Thanks