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1989 Matsuura MC-760VX YASNAC MX3 with probable bad controller boards.


Nov 12, 2011
Tacoma, WA
There is a MC-760VX going for the bargain price of free. I'm looking for a machine I can setup to make parts on the side, and eventually turn into something more if I can get enough business. Turnkey ready isn't necessary for me, but I don't want a money pit either. Talking with the current owner it seems like some of the control boards may have bit the dust. I'm willing to spend about $5000-$6000 to repair/upgrade the machine before I decide that a running older VF-2 will be a better option. Most of my controller experience is on Haas and Fanuc, with some ancient Okuma thrown in.

Assuming that I have to replace a few boards, and that all parameters, settings, programs have been lost; what am I looking at for cost to get it up and running again? I will also be looking for options to upgrade the spindle from the 4500RPM unit it currently has.

current owner said:
“Machine has a 325 SERVO CPU ERROR alarm that won't clear. Looked up alarm in the manual and it states to contact your Yaskawa representative and also replace MB20. Called into Selway and left all info; awaiting a callback. Selway is still troubleshooting as of 10/21/2019.

Cable is here ready for install. 10/22/2019.”

“We managed to clear the 310 alarm by forcing a bit the servo on with parameter 1322 bit 7. Now able to move Y axis but will over travel. X axis will bomb out and same with Y axis. The 4th axis when it we try and move we get multiple alarms. Meg the 4th axis motor found the motor to be good but cable between motor and connection in side work area is bad. Will need to replace the cable. We are still chipping away at the other alarms that will appear for others. For now we are going one alarm at a time to figure out everything that is wrong with this machine.”

“Worked with Robby to figure out issue with machine. Swapped power supplies and still keep getting alarm 310. Swapped mm20 board and got the 310 alarm and 322 alarm now. Still working out what is causing this issue.”

Issue immediately prior: “PC CPU Error cant clear, Machine down, James/Vendor cleared 329 alarm. Probably caused by bad commutations cable, chip in board, or bad machine ground.”

We believed that the issue may have been corrected by replacing this part:

YAI Part #: NCX3320
Description: JANCD-MM20/ DTN-4790/X3 MEMORY BOARD

We did not have conclusive evidence that this would solve the problem, and the Yaskawa tech support recommended coming out and swapping boards until the problem was resolved to troubleshoot the issue (meaning they weren’t sure either). The faulty axis cables were replaced

Thanks for any input you guys have.
How much is rigging? If you can move it for under a grand and budget a couple thousand for a tech's time and parts you might do OK.

The 4500 spindle pretty much kills the value of that thing though. It will never be worth what you put into it.

Changing the spindle RPM would be very involved if possible at all. Certainly cost far more than buying a better machine.
Worst case scenario if it is free and low cost rigging is available and you can't fix it on the cheap you can part it out on E-bay. A couple years ago I had a Yasnac MX3 controlled machine that became a money pit and when the power supply died I said enough is enough and parted it out on E-bay. I was amazed that I ended up clearing damn near $4,000 on a machine that was probably worth less than $1k where it sat whole not running.

No way to know what you could spend to fix your machine, with the machines age and controller don't even consider it unless you have the knowledge to try to repair yourself. This is not a case where it would be worth the gamble to call in a tech to try to fix it.