Hey guys, I've got a DSL40CR and I wish to add phantom power to the MIDI connector so I don't have to power my foot controller with a wall wart. I've done it before by mounting a small power jack to the chassis and wiring it up to pins 1 & 3 (1=ground, 3=V+) to the MIDI IN connector. It works great because it's usually very difficult to run a 12 volt cable out to the front of the stage to the foot controller. I wanted to avoid drilling any holes in the chassis this time and instead find a 9 to 24 volt DC source within the amp and hook it to the MIDI connector like I usually do. Are there any suggestions as to where I could tap into the circuit innocuously?
Adding MIDI phantom power to DSL40CR
- Thread starter Rubyfocus
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Jon Snell
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If you don't need more than say 80mA, I would tap across LT2. That will give you 12volts ish.
Pete Farrington
Well-Known Member
Marshall don’t seem to allow those schematics in the public domain, so only Marshall techs such as Jon, with the necessary access privileges, can help really.
Well, so I hooked everything up, took a 12V line and it's accompanying ground across the V1 heater (LT2) and hooked it up to pins 1 & 3 of the MIDI connector. Used my known 5-conductor MIDI cable (Not all MIDI cables use 5-conductor cable) and switched everything on. Everything powered up, Success! But alas, for some reason, the amp did not want to respond to the MIDI commands sent from the footswitch anymore. Fiddlesticks! Perhaps the 12V in the amp doesn't supply enough current or is too noisy to do the job, even though the amp sounded fine. Or maybe some odd disruption of the MIDI current loop and it's relation to ground, I dunno. It looks like I'm back to drilling a hole in the chassis and installing a barrel jack and powering it up with a wall wart at the amp. Not nearly as elegant, but I suppose it will do....
