SOLUTION: The SC-88 defaults to GS mode when factory reset (initialized), which is the cause of my MIDI playback issues. Setting it to GM mode (powering on while PART > is held down) will switch it into GM mode

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I seem to have inconsistencies playing back MIDI files on my SC-88. Sometimes.

If I play back a file through any player I've tried, it seems to not want to set instruments on channels 1 or 9. This is independent of the system used. I've tried it on both my DOS PC (with a PCMIDI ISA card) and my main Desktop (with a Roland UM-ONE) and I get the same problem.

For example, PASSPORT.MID has channel 1 set to Honky Tonk, and channel 9 set to Orchestra Hit, but my SC-88 has them both set to the default "Piano 1". It also briefly displays "NO INSTRUMENT" on those channels when starting playback.

Playing back Doom E1M1 MIDI will leave channel 1 as Piano 1, but will occasionally change it to Distortion Guitar if I try enough times. When playing the actual game, however, it sounds fine every time.

I also have a Yamaha MU80 connected to the DOS PC (through a MIDI Solutions Quadra Thru), which plays back MIDIs fine. Also, bypassing the splitter doesn't help, so that's not the problem.

I've tried initializing the SC-88 immediately before playback (powering on while holding Instrument < and >) but that doesn't help either.