Mitsubishi MDS-CH-CV power supply

[superstardeejay]

Hi, we have here a Yamazaki Mazak Machining Centre fitted with Mitsubishi MDS-CH servo drives.
The Servo power supply has a 'C' on the display. Does anyone know what these codes mean? Mitsubishi say that only Machine Builders may learn of these codes.

I've been told by various 'experts' that C means that its either ok, that it has a hardware fault, that it has a memory (parameter) fault...so Im none the wiser now.

[gridley51]

Send me a PM with your email address.

Mark.

[Rokkin]

6C means main circuit Error......"Charging of the main circuit has become abnormal"

Isolate the PN bus on the power supply with the rest of the servo system. Measure the bus with a meter to see if there is a short. The problem is almost always the power supply itself.

[superstardeejay]

Hello! The power supply is giving out 590V DC on the DC busbars, which seems about right. (AC supply is 415V AC 3-phase). The machine operator says that normally the power supply should show a letter 'b'.

There's only a single digit 7-seg LED on these, so error codes are single characters.

[onthebumper]

Check this manual. http://www.meau.com/functions/dms/ge...00001040100000
On page 66 it will list some things to try for 6C alarm. 6C should be showing on one of the attached drives and c is the equivalent on the power supply.

[superstardeejay]

Hi onthebumper, many thanks indeed for the link, that is manual I've been looking for; it's not on the Mitsubishi UK website, and I can't externally access the USA mitsubishi website as it's blocked to non-US browsing for some reason!

I've had my nose in the machine today and managed to get the boss to let me swap the suspect power supply with one from another machine; this proves that the error moves with the power supply.

A good unit starts A > b > C > and finally d when it the CNC issues a drive enable command.
The faulty unit starts E then changes to 'o' when the CNC tries to run the drives.

We had a cooling fan start bad arcing at about the time this fault first showed up, (the fan motor was full of coolant); I'm wondering if the interference has somehow conducted into the servodrive and scrambled the power supply CPU or NVRAM ic. The boss wouldnt let me swap the CPU cards.

I dismantled the power supply (I'm a former inverter VFD service tech) but can't see any component failure doing cold checks; no IGBT problems, electrolytics all test ok etc.

Does anyone know if there's any parameters this PSU needs loading with? I'm all at sea with these MDS systems, I've had similar problems with Fanuc which I've been able to sort by fac.resets and parameter set reloads.

Cheers,
kevin

[onthebumper]

There are no parameters in the power supply unit. There is only software that is written to the power supply but this can only be done by Mitsubishi through special tools. On a side note the servo and spindle drives do have parameters but they are written from the control every time you power up so there is no need to manually write them or even back them up. For this reason it is very important to back up the NC parameters.

[superstardeejay]

I guess that maybe the 'firmware' is corrupt! I'm going to send the psu away and win myself a large bill!!
I'll post the outcome if they tell me the score.

Kevin

[superstardeejay]

Latest update to my little problem, the PSU was sent away to a dealer and they returned it saying they couldn't find the fault! So it's back here, at least it wasn't something so simple as to make me look like an idiot..though that's the least of my worries.

Yamazaki Mazak UK are going to be the next port of call I suspect...that's bread and cheese for dinner for the next year then....

[botha.y]

This means Ready ON, servo OFF.

[girishdk]

Hi,

The problem could be incoming power supply quality side. We had similar problem in year 2000, when Mitsubishi had launched MDS-B-CVE xxx Power Supply, which was not getting into ready mode at some customers.

After many trials, we found it does not get ready if the supply frequency is not in the range of 50 Hz +/- 2 Hz, i.e. it should be 48 - 52 Hz.

Temporarily we had replaced them with B-CV xxx & later Mitsubishi modified the firmware for the CVE units.

Since the unit was working fine at their service centre, you can check the Voltage, frequency, temperature etc are within the limits in the shop.

Anyway Mitsubishi are the best people to find out this.

All the best.

Girish

[snk]

please go through the remedies given......

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