MIDI Phantom Power over cable illuminates MP-201 LEDs. Bad?

Kent · Post by **Kent** » Mon Nov 30, 2009 4:09 pm

Hello forumites,

I have a Ground Control Foot Pedal that I use to send program changes to a some MIDI gear, including an MP-201. It is powered remotely via a 7-pin DIN cable that goes to box that changes that to a 5-pin cable. This 5-pin cable goes to the MIDI In on the MP-201.

When the MP-201 is turned off, and this includes the removal of the power cable, the LEDs glow dimly as long the MIDI Input cable is connected.

Is there any harm in this? I know that powering over the MIDI cable is part of the MIDI standard, but I'm wary of how observant some are regarding standards.

Thoughts or ideas?

Thanks,

Kent

theglyph · Post by **theglyph** » Mon Nov 30, 2009 5:30 pm

I could swear that there are only two of the 5 DIN pins used on the 201. One for transmit and the other for receive. This input is of course opto isolated.
Getting power thru doesn't sound right. Perhaps I'm wrong. Sounds like a good question for Amos!

Amos · Post by **Amos** » Mon Nov 30, 2009 6:56 pm

The other DIN input pins are not completely unused on the MP-201; we included some circuitry to allow us to possibly support DIN Sync, although this has never been implemented.

This means that there are a couple of resistors on the MP-201 that you could remove to disconnect these "extra" pins, and it would probably stop this LED-glowing situation from happening. I would recommend removing those resistors if you have (or a friend has) some soldering experience. I'll PM with more info.

And, sorry about the teaser info re: DINSync... no idea if we will ever implement this for real, or not. There's very little room left in the code, and if it comes down to adding more LFO features or supporting DIN Sync, I will probably go with the extra LFO features first.

-Amos