My Marshall JCM800 4010 combo was sounding a bit “off” at a gig at weekend so I bought it home to take a look at. Anyway, I’ve owned this amp for about 15 years but I just realised that it looks like it’s been modded. There seems to be an unmarked extra socket on the back plate and I have no idea what it is for. Anyone hazard a guess what this might be for? I’m a bit unsure if it’s an output, input or even for a foot switch.
Any ideas how/if I could test what it does without opening up the chassis and trying to figure out the circuit (or blowing myself or the amp up).
The socket on the far right.
Comments
If you’ve already taken the back panel off it’s just another four bolts.
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein
flanging_fed “
Remove it and wire the speaker jacks directly to the selector as they should be.
Then think of something useful to do with the extra hole...
"Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski
"Only two things are infinite - the universe, and human stupidity. And I'm not sure about the universe." - Albert Einstein