Some time ago I purchased the JX-10 Sysex Enhanced ROM from Colin Fraser which makes the JX-10 respond to sysex the same way the MKS-70 (the rack version of JX-10) does. It’s only £15 including postage to Europe, so no need to hesitate. Remember to buy it directly from Colin, not from other sellers on eBay. Colin has put a lot of work into this!
Note that you have to have an M64-C cartridge to be able to load the original patches with sysex, the firmware upgrade won’t change that. When the patches are on the memory cartridge they can be copied to the internal memory.
The new EPROM arrived in a static bag attached to an important note informing that inserting the EPROM the wrong way will damage it. It also had a non-clickable link to the installation instructions.
I did exactly as in the instructions, but with the following three exceptions:
- I checked the versions before and after by pressing H while turning on. This was most for fun.
- I unscrewed the two screws underneath before the ones on the sides (note: in Colin’s instructions the screws underneath are described as “two larger bolts” – on my JX-10 they were screws).
- I did actually not have to loose the flat cable. It was long enough to give the space needed for the ROM swap.
