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MCK-70 Memory Checker for the Roland MKS-70 and JX-10.

Introducing a fantastic utility, MCK-70 is a memory checker for the Roland MKS-70 and JX-10, developed by non-other than Guy Wilkinson.

A few weeks ago, I received a Roland MKS-70 from a customer in Canada. He’d just had it upgraded with Guy Wilkinson’s fabulous VFD module and Fred Vecoven’s PWM mod but then weird things started to happen. This machine was then sent a couple of thousand miles across the Atlantic to see what I could do with it.

The first thing was to fix the power supply. It was totally shot. Signs of heat damage and all regulated outputs showing zero volts except the -15V line which was reading -21.5V, wasn’t a good start. Oh dear. Anyway, I got that going temporarily as the customer agreed to have Guy Wilkinson’s P0004 switched-mode power supply installed.

The next issue was that some voices weren’t playing. After going over the voice-boards and confirming that they were both okay, I decided to look at the assigner (CPU) board.

To keep things simple, I disconnected the Vecoven PWM mod and I also installed the original Roland firmware. This meant that I had to have the voice-boards connected which is a bit of a pain.

After a lot of testing, chatting with Fred Vecoven and Guy Wilkinson, it seemed clear that the machine had a memory issue.

Guy told me that he’d developed a little bit of software to test the RAM in the Super-JX and we agreed that this would be a perfect opportunity to actually check it out.

Guy e-mailed me the bin file, I promptly burnt a ROM, installed it into the MKS-70’s Assigner-board and switched on. Oh wow! This is so cool!

MCK-70 in action

Running in the processor's on-board memory and thereby leaving all other memory free, MCK-70 systematically checks not only the main RAM but also the gate-array RAM, writing all zeros as it sweeps. After a few seconds, you end up with an ultra-clean slate, a Super-JX that's cleaner than factory!

I then loaded some factory stuff into the MKS-70. Wow! All looking good so far. Programming a very simple tone and patch confirmed that everything was working and that the issues that were present before, were all gone. Guy, you’re a genius! THANK YOU, my friend. 🙂

MCK-70 Boot
MCK-70 will work on the Roland JX-10 as well as the MKS-70.

It was obvious that MCK-70 would be really useful to others and so Guy and I decided to make MCK-70 Memory Checker for the Roland MKS-70 and JX-10, available to purchase in my on-line store.

A great tool for anyone who may have similar MKS-70 or indeed JX-10 memory corruption problems, MCK-70 will save you a lot of hassle and money. Removing the TC5564 RAM chip requires removal of the assigner-board and unlike the voice-boards, the assigner-board has a couple of delicate membrane cables connecting it to the display board and the cartridge board. You really want to avoid disturbing these, if you can.

On top of that, the TC5564PL-15 isn’t at all easy to get hold of and hey, why on earth would you want to change the RAM chip in your Super-JX if you could know that all that’s happened, is that the memory’s got a little… well, bent?


  • When purchasing, you can select your preferred format; a downloadable .bin file or a physical ROM. If you buy the former, you'll need a ROM burner to put the program on to a 27C256 ROM. If you buy the physical ROM version, that'll be sent out to you.
  • This will totally delete the memory in your machine. Don't mess with it unless you actually have an issue or your machine's memory is backed up.
  • Although I've used a real case study involving a customer's MKS-70, MCK-70 will work in the Roland JX-10!