MBSEQ MIDIOUT Fix

Note: it seems that this modification is only required for MIDI devices which don't comply to the MIDI specification!

Usually the MIDI IN port of a device has to work correctly when the current through the MIDI wire is at least 5 mA.

3.3V / (3 * 220 Ohm) = 5 mA

I think, that the opto LED opening voltage is missing form the equation....It's 1.3-1.5 V typ.

In case of 6N138 at the receiver side, the 3.3V supply cannot cause any problem.

But it's problematic if you use 6N136 as suggested somewhere. I've some bad experience.....