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analogTinkerer 16th May 2019 05:23 PM

JX-3P rom upgrade?
Hey all,

I've had my JX-3P for a few months now and I must say that I really enjoy it. However I would really find it useful to have it respond to midi velocity. I know the Kiwi Mod exists, as well as the Riversynths MIDI expansion kit, but I read in an old Sound on Sound article that Roland had a ROM upgrade that added velocity, which seems like it would be much cheaper and easier to install.

I found a couple ebay listings that claim to be the velocity ROM (version 4.0).

Has anybody tried the ROM upgrade? Does version 4.0 definitely add velocity? (over midi of course). I managed to obtain a copy of the version 4.0 ROM image, how difficult is it to burn one myself? Which EPROM chips can I use?

hazboss 24th June 2019 11:29 AM

I can't tell you about v4.0 - but I did the Kiwi 3P mod and de-soldering the ROM chip was not fun!

I could send you the EPROM I removed if you want to experiment. I had to cut some of the pins but you could make a daughterboard with some stripboard.

analogTinkerer 30th June 2019 05:40 PM

I actually ended up buying one of the Ebay roms, which wasn't too expensive. Luckily the ROM in my 3p was socketed. Unfortunately while the rom chip works ok, it doesn't seem to add velocity over midi as claimed, so I will be taking this up with the seller. Holding down '7' during power up is supposed to activate velocity over MIDI as I read in the SOS article, but with the rom I got this does nothing. Anyone know if there was an alternative method on different rom revisions?