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MV55 Spindle Drive Problem

wkwar

Plastic
Joined
Mar 29, 2019
Dear All

Wonder if you can point me to the correct direction.

Have a Mori MC-55 with a Fanuc a06b-6044-h010 Spindle Drive

Machine use to work and we recently we get Alarm #2 when we send a speed signal to the drive. Drive will not alarm if we send S000.

Disconnect motor with same result

So far. Check fuses, rectifiers, IGBT all are fine.

Check clock and DC voltage and they are fine.

While we were trouble shooting today. It threw alarm 1 and 4 upon power up. . Check overheat switch and we get a continuity at the Honda connector. Pulled main board and notice a metal chip stuck in the back. Pulled chicp, clean board, e-prom and re intall board. Still have alarm 1 and 4.

What is next?
 
Update - Alarm is 4 and 1 so 5 which indicate blown AF2 or 3. Sure enough, AF3 is blown. What could suddenly cause this?
 
The fuse blow might be related to the metal chip on the board. Hard to diagnose that without knowing where the chip was and if it may have shorted the power section of the board.

If you are sure about your transistor modules being good, Alarm 2 can also be caused by a burned out current sense resistor. They are labeled R5 and R6 in my diagram They are white ceramic resistors on two legs of the output power to the motor. Located in the lower right area of the drive cage, just above the terminal strip where the motor power leads connect to the drive.
 
Hello Vancbiker

Thanks for the reply

after i pulled the chip i then remembered that i should have taken a picture of it. It if somewhat in the middle of the board. Since we did not blow the fuse earlier, i would almost assume that while i was messing with the board, the chip finally came in contact with something the blew the fuse. it was wedge on the solder pins pretty good.

seems like AF3 goes to the trigger circuit if the IGBT?

measure R5 and R6 while they are hookup. The have continuity in very low ohms. Do you recall their values? Unless i am getting a false measurement with it in the circuit?
 
.....seems like AF3 goes to the trigger circuit if the IGBT?

I may have board level schematics for that drive. Post the Fanuc part number for your board and I'll see what I have.

...measure R5 and R6 while they are hookup. The have continuity in very low ohms. Do you recall their values? Unless i am getting a false measurement with it in the circuit?

I have always checked them with the motor cables disconnected and the top board removed. Then you can be sure to not have a false reading through other circuits. They are a very low ohm value. I will look at my schematics tomorrow or Monday and see what information I have.
 
AF2 and AF3 protect the power supply portion of the board where +5V +15V, -15V, and 24V are created. They also provide power to the pre-driver transformer (T2), and voltage regulator transformer (T1). So blowing AF3 could occur by a short at lots of places on the board.

AF1 protects the regulated +5V output of the power portion of the drive.

The current sense resistors are spec'd at .007 ohm and 40W. When they are bad they will show as open circuit or high resistance.

If your current sense resistors are good and your transistor modules are good and you still get no rotation and alarm 2 then it is likely that your board is bad. There are some tiny fuses near the connectors along the right edge of the board. They are plastic cased fuses about 7mm wide by 10mm tall. These try to protect the pre-drive section of the board from damage when a short occurs in a transistor module. It is rare, but I have seen these fuses fail without explanation. If those fuses are good and you are sure your transistor modules are good and the current sense resistors are good and there is still no rotation then it is most likely that the board is bad. Troubleshooting that goes beyond what I can do over the forum. If you want to try troubleshooting the board, you will need an oscilloscope and pretty good understanding of electronics. In almost all cases a job best left to Fanuc or independent repair outfits like TIE.
 
will recheck the current sense resistor again. check the predrive fuses and they are fine. the AF3 did not blow till much later. so i am speculating that the chip move enough to short out something. anyway you can take picture with your phone and send them? i have scope and can trouble shoot boards if we have the schematic.
 
Hello Van

Current sense resistors are good. Check the drive transistor on board at they seem fine. Use a temporary 1A instead of 3A ( may not be enough) fuse blows.

Can you possibly upload picture of the schematic around the AF3? AF2 is fine.

Also, if i would to buy a use one from Ebay, it is just a matter of setting the dip switches and i am good to go?
 
I'll try taking a picture with my camera and see if it is clear enough to work.

For a used drive you will need to be sure that they have the same ROM or install your original ROM on the replacement board. Jumpers and ROM control max RPM on this drive. Since this is an analog drive you should adjust pots on the board for best performance. Appendix 8 in the spindle drive maintenance manual describes the pots and adjustment procedures. This will be mainly needed if you can do rigid tapping on the machine and want nice threads. If you use floating tapping then not so important.
 
Schematic page showing AF fuses... Posting to the thread automatically compresses the file so it is too small to really be useful.

PM me with your e-mail address and I'll send e-mail with the full ~5mB file attached. I think it will work for you.
 

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