[stang5197]

On a '88 Mazak 8SP lathe, we just replaced the complete AXIS AC SERVO DRIVE AMPLIFIER

Machine powers up fine, but has an Emergency stop alarm that we can't reset. There are two operator E-Stop buttons, that seem to ohm out fine, and they don't appear to be the problem.

When we try to reset the alarm, it comes back after about 10 seconds. If one of the operator E-stop buttons is pressed the alarm never clears off the screen.

We don't have any schematics for the machine, so we are having a hard time trying to find the cause of the alarm.

Under the diagnostic screen, the emergency stop alarm is the only one present.

Any ideas on what the problem could be? Checked all of the breakers, etc. in the cabinet and nothing appears to wrong.

[Leelund]

Recheck your cable connections to the servo drive, especially the buss connection cable. Make sure they are in the correct connectors. The dual drive, NC and the spindle controller are all daisy chained together with a terminator at the end of the transmission chain. What Series NC control is on your MC? What model drives do you have and what model spindle controller are you using. What does the LED indicators on these drives say? Good luck.

[stang5197]

Are the buss cables the ones that are circled in the picture?

The controls are a T-2, with Mitsubishi drives #MR-S2-80B-Z33

F1, F2, 55, 61, 62 we flashing but keep in mind at that time we trying to verify that the operator e-stop buttons were operating correctly, so some of the errors might correlate back to that.

[Leelund]

No, the axis feedback cables are the ones you have circled. The long slender one with long rectangular connector is the buss data cable. Right beside it is the terminator. They are in sockets CN1A and CN1B. The F1 and F2 are names of the two axis X and Z. The 55 is the drive is in estop but I can't find an alarm 61 or 62 in the drive manual. The 61 and 62 may indicate something is amiss with the dual drive yet but not sure. The T-2 control is throwing me also as I thought the T-2 had DC Servo Drives not AC, and I didn't think the T-2 could be buss linked to the servos. Sorry. I'll keep researching the 61 and 62 alarms on your drive. Someone else here may know right off.
Lee

[stang5197]

I swapped the connectors and repowered it back up, but still have an E-Stop alarm.

The code now is 56, actually F1, 56, F2.

Attached is a screen shot as it shows both axis in alarm 56.

The only difference now that the cables are switched is that when you try to reset the alarm, it comes back on immediately, it doesn't wait 10 seconds as before.

[Leelund]

I think the alarm situation is better. The flashing F1->56->F2->56 means the alarm is in another axis downstream in the communication stream. So your servo drive is ok. Check your spindle controller. Does it have a LED display on it and if it does what is it showing? I found in the MRS Servo manual that the buss data cable should be plugged in to the connection on the board marked CN1A. CN1B should have the terminator in it.

[stang5197]

I checked the connections and they were backwards, so they are correct now: the terminator is in CN1B

The alarm is 55 now, I will have to check and see what that error means as I don't have the manual at the shop. Now when the E-Stop alarm is reset on the OP it stays off for about 5-10 seconds.

When I press an operator E-stop the alarm changes to E7 so they appear to be working fine.

On the AC Spindle controller it doesn't show an alarm, just r 0 which doesn't correlate to anything on the cover of the controller.

I will try to call Mitsubishi Monday morning to see if they can help, I will keep you posted.

[Leelund]

Yes, R0 is normal for the spin control. I thought the servo might be daisy chained to the spindle controller but I see it's not. The servo control cable goes to the FX81 card in the NC. You can download the MRS manual from Mitts web site. Sounds like you may have something machine side though holding you in EStop. A NFB or thermal relay or something like that. I have some ladders that are close but not for a QT8. Sorry couldn't nail it down. Alarm 55 just states Emergency from the drive manual. Don't that drive have a circuit involving the B and R connections that have something to do with E Stop?

[stang5197]

Yeah I found the manual last night. For anyone else following this here is the link the the mentioned Mitsubishi site: http://www.meau.com/eprise/main/site...e=&ManualType=

I will call Mitsubishi service tomorrow and post the problem. Mitsubishi seems much more helpful then Mazak, as Mazak's service is far less then impeccable.

Lee thank you for all of the help that you have given so far.

[onthebumper]

Leelund is absolutely correct. There should be a jumper wire between B and R on the drive. Some machines have three phase power switched to the drive to the B terminal as an external emergency stop but most just have a jumper wire placed between the terminals B and R. You can pull the jumper from your old drive or just fasten a wire between the two. Be careful that the wire doesn't touch anything else or you'll have to buy another drive.

[stang5197]

I didn't catch that when Lee mentioned that earlier. I called the guys at the shop and sure enough there is a jumper on the old board and there isn't one on the new.

We will hook it up this afternoon and give it a shot.

[onthebumper]

Sometimes they bend the jumper down so it's hard to see. It is a very common alarm when ordering a new MRS drive unit. Almost none of the machines actually use that function too.

[stang5197]

Sometimes they bend the jumper down so it's hard to see. It is a very common alarm when ordering a new MRS drive unit. Almost none of the machines actually use that function too.

Yeah it was bent back and had a nice black coating so I never saw it.

None the less, I put the jumper in back and blew out a capacitor on the middle board again. Gave a nice large spark show.

C49 (I think is the capacitor that blew out). Luckily we can take one off the old board and replace it as it didn't burn the board.

Called Mitsubishi tech service and they are saying that there is a problem with one of the motors or the cables. So the next step is to meg the motors and cable.

Which apparently is what we are assuming at this point is what burnt the board the first time.

I have to borrow a megger tester so I will post the results after we get it checked.

[Leelund]

Stang,
I apologize! I assumed that you had found the original problem and were just having problems marrying up the drive to the machine! I have been there in that position and it's an awful feeling when you use the servo for a big expensive fuse. Probably a cable, one that goes through a power track, especially if your machine uses that spring steel type. Those AC motors are a pretty hardy lot. Make sure you have disconnected all the electronics from the circuit before you use that meggar. They, the electronics, make expensive fuses also. Lee

[onthebumper]

Hi Stang. You can do a quick test on the motors to see if there is any problem without a megger. The megger will show you problems that you would see intermittently with high readings. You can use a standard digital volt meter set to read ohms. If you disconnect the motor leads from the drive and measure (on the cable, not the drive) from U to ground, V to ground, and W to ground you should get infinite ohms. Any type of reading is not good. You can also check U to V, V to W, and U to W. You should get a low ohm reading but they should all be pretty balanced. If you get a bad reading then this will save you from getting a megger. Although a megger is not bad tool to have around, especially if you have several machines.
Good luck!

[stang5197]

No problem at all, it is my fault, Mitisibushi recommend megging the motor after the first board burnt up.

I thought we had found the problem as the machine was not grounded so we thought that was the problem from the first time.

I have a buddy that has a megger so I just have to swing by and pick it up and try and determine where the problem is.

One of the motors was rebuilt by a local motor shop previously by the previous owner, so I am hoping it is just a cable. Hopefully I should be able to get it done by the end of the week.

Ken

[stang5197]

Hi Stang. You can do a quick test on the motors to see if there is any problem without a megger. The megger will show you problems that you would see intermittently with high readings. You can use a standard digital volt meter set to read ohms. If you disconnect the motor leads from the drive and measure (on the cable, not the drive) from U to ground, V to ground, and W to ground you should get infinite ohms. Any type of reading is not good. You can also check U to V, V to W, and U to W. You should get a low ohm reading but they should all be pretty balanced. If you get a bad reading then this will save you from getting a megger. Although a megger is not bad tool to have around, especially if you have several machines.
Good luck!

I will give it a try this afternoon and post the results tonight. Thats for the idea.

Ken

[chippy1]

Take a snap shot of the version screen also in diagnostics and show the versions on this thread too us. You didn't happen to loose any parameters did you? Also check the switch on the FX715 card to make sure your PLC is running.

Regards,

Chippy,

[stang5197]

Hi Stang. You can do a quick test on the motors to see if there is any problem without a megger. The megger will show you problems that you would see intermittently with high readings. You can use a standard digital volt meter set to read ohms. If you disconnect the motor leads from the drive and measure (on the cable, not the drive) from U to ground, V to ground, and W to ground you should get infinite ohms. Any type of reading is not good. You can also check U to V, V to W, and U to W. You should get a low ohm reading but they should all be pretty balanced. If you get a bad reading then this will save you from getting a megger. Although a megger is not bad tool to have around, especially if you have several machines.
Good luck!

Checked the connections with an Ohm meter and here is what I found:
Z Motor
U-Ground 1.6M Ohm
Y-Ground 1.4M Ohm
W-Ground 3.2M Ohm
(I don't feel real confident in these readings and I couldn't ever get them to repeat, very flaky not sure if it is the meter or not).

Z Motor Cont.
U to V - 1.1 Ohm
V to W - 1.1 Ohm
U to V - 1.0 Ohm
(These readings were very consistent)


X Motor
U-Ground 1.7M Ohm
Y-Ground 1.9M Ohm
W-Ground 1.82M Ohm
(I don't feel real confident in these readings and I couldn't ever get them to repeat, very flaky not sure if it is the meter or not).

X Motor Cont.
U to V - 4.6 Ohm
V to W - 4.5 Ohm
U to V - 4.5 Ohm
(These readings were very consistent)

Not sure if these reading are legit due to the inconsistency when going to ground, I will try it again with a different gauge tomorrow.

Also have a buddy coming over on Thurs. to meg the motors to hopefully get a better idea of where the problem is.

Again thanks for all of the help so far guys.

Ken

[stang5197]

Take a snap shot of the version screen also in diagnostics and show the versions on this thread too us. You didn't happen to loose any parameters did you? Also check the switch on the FX715 card to make sure your PLC is running.

Regards,

Chippy,

I don't think so but can't be real certain. Without the jumper installed I could check the parameter screen and everything looked OK. Unfortunately I can't take a picture of the screen at the moment, once we get the board operational again I will post it. The only thing I have right now is the picture in post 5