battery holder makes it sound like the blue ridge rom mod, especially since yours is the "old" MT32 which the blue ridge rom mod was for.
1.07 was the last roland version of the rom for the "old" mt32, and the blue ridge rom I think was based on 1.04 or 1.06...

there is a few mods, they are all the same. RWI, Blue Ridge etc.

Thanks for reply. Still curious though, these roms were made in 1988, year before Rwi work? Maybe i am wrong? Could you tell little more, what signs or things to spot so to know what has been done to this? Why the marking 2.06? What is the origins, are there other model numbers of the makers info somewhere? This had two AA battery holder, not cr2032. As a more of a gamer and collector, it would be nice to revert mods. Would "new" 1.07 roms revert things surely? -A-

all the mods to the mt32 I've see are all the same (different people doing/claiming) but there are two basic mods;

1 - Battery backup patch memory, which requires the rom on startup to not zero the memory (hence the modded rom)

2 - Putting a trimmer on the DAC for noise reduction.

why 2.06? who knows. the RWI mod, the Blue Ridge mod, your German Mod are all the same thing. (my blue ridge roms are dated 88 as well).

Thank you for the info, I did read Rwi document of the mods he has made, and in this conversation looks like Rwi did also more hardware mods: Testing of a RWI Modified MT-32.
So maybe only visible mods what my device holds is the battery mod and maybe the trimmer plus roms, have to check. It is really hard to find something that you do not know what or where to look. Rwi did mods for roms to improve snr, and reverb sounds were lowered what i can remember of the document? Would there be possibility that new set of 1.07 roms would harm or would not work in current state of my Mt-32? -A-

Got this double tested today, all service tests went without problems, test notes comes from 6.3mm plugs to speakers. Still midi message light wont blink and no midi songs played from Pc come out of it. Pc midi cable transmits data with blinking led. When switched midi to out or through, Input led blinks on midi cable. No sound still on 6.3mm outputs.
What might be wrong? Input stage somehow stuck? Allthough full reset done, and something changed better on screen. Could it be the Eproms?
Thanks for any help. -A-

Its been a while. Changed roms to newest originals 1.07, but no help there to the situation. Any hints or tips?