[Moldmaker74]

I have a Leadwell CNC mill with a Mitsubishi Control and HA80NC-S servo motors. I had a problem with the servo motor on the X axis intermittently tripping due to overcurrent. It would using make a high pitch noise (like too much gain) and then it would fault out. I replaced the cable and connector this seemed to cure the problem for a few months. The motor started acting up again so I switched it to the Z Axis and the problem has followed the servo motor.

I am trying to take the servo apart far enough to blow it out good and see if I can buy myself a little time. I cant seem to get the case open enough. I haven't forced anything yet but it will open up about 1/16". I have the housing cover off of the encoder to loosen up the screws. Does the encoder need to come out? I took the 3 screw out of the flange but it doesn't want to lift up.

[Al_The_Man]

I had a problem with some HA80 motors, but they were different type encoder than you have, Does the white button pop off and reveal an Allen Head bolt? They look almost like Fanuc style mounting, and this is the way these are removed.
BTW, I had the same symptom, and it turned out to be a disk had come loose in the encoder.
Al.

[underthetire]

Encoder needs to come out. Should be a cap screw under the white plastic cover on the end.

[Moldmaker74]

Thanks guys!

I took off the sticker, found and removed the cap screw underneath it.

The encoder is still tight... what next??

I hope I get lucky and that I find out it's a loose disc, they want good money for a replacement.

[Moldmaker74]

I found a jack-out thread inside the c'bore... I am going to run up to the hardware store and buy the metric screw.

Will the disc be visible after I get the blue cap off?

[Al_The_Man]

The problem is that if the disc has come loose you need to orient it correctly when you re-attach it as the commutation tracks are on it.
Al.

[Moldmaker74]

I took the cover off of the encoder and the disc appears to be tight. A little bit of dust came out of the motor when I blew it out but the problem still persists when I reassembled it and put the servo back in.

Looks like I will have to look for a replacement. The encoder is a Tamagawa Seiki FA-CODER. If I buy a used servo online do I have to make sure that it has the same encoder or will they work the same as long as the connector matches up?

[Al_The_Man]

The variation usually comes in the mounting, any of the encoders that have the MS3102A.22-14 connectors have the same pin out.
If you buy a complete servo with the same MS connector, the only other variation could be in the encoder resolution, so you would need to change a parameter accordingly.
These encoders use a 4 wire serial communication.
Al.

[Moldmaker74]

Thank You for all of your help Al!

I will try to get something here this week and will post either my results or any follow up questions I might have.

[onthebumper]

You can swap the encoder very easily to a new motor. As long as it is the same motor model it will mount up fine. Just make sure you line up the encoder shaft with the pin on the motor shaft. Also make sure the three tabs on the encoder are positioned correctly. One of them is different from the other two in that it lines up with a pin on the motor plate.

You can also try to send the motor out to be rebuilt. There is a company in IL that specializes in Mitsubishi motors and even has Mitsubishi CNC and drives to test the motors. Their name is Endeavor Technologies. Very good company and easy to deal with.

[Moldmaker74]

I have been watching the machine closely and I am starting to think that it is more likely the Encoder than the Motor at this point. It usually jerks before it faults and other times it wont move when it should then faults.

I found the same motor PN but the encoder PN is different. My encoder is a OHE25K-6 (MEAU.com Material Number: B55001) and the other one is a OSE253S (MEAU.com Material Number: B65002). As mentioned earlier this should still work correct?? The mounting pattern and shaft interface is very different from each other.

On a secondary note locally I found a HA80C-S motor... When I called Mitsubishi to ask what the difference was between that and a HA80NC-S, they told me that the NC-S was a newer motor designed to work with the newer servo drives. DO you know if there is a big difference?

Current options:
-New encoder from Mits $1241+shipping
-Used matching PN motor with different encoder but same connector for $850
-Used Similar but different older motor and encoder $250 but might talk the seller into trying it before buying it.

Ideas??

[Al_The_Man]

I would recheck with Mitsubishi on the #2 option, if this is a Mitsubishi control, the motor type part number may have to be entered in the parameters, if the resolution is the same it should work OK.
Al.

[Moldmaker74]

I wound up buying the HA80NC-S with the OSE253S encoder. The machine is up and running now and no parameter settings were required. As you suspected the control reads both encoders the same.

Thanks again for your help!