[kalawa]

We have a Mitsui Seiki horizontal milling center with Y axis brush dc servo motor A06B-0653-B212 and drive A20B-00009-0320/15E.

The motor was removed for making grinding noises and brake was found to have been fitted incorrectly previously. It re-set tested and re-fitted. The motor commutator was cleaned with fine wet/dry.

On re-installation the motor was found 'humming' but was turning both ways (without load) for a while then it stopped with above alarm. Fitted onto ball screw but still did not turn but humming gone.

Checked relays and all ok. But found that when Y axis is moved, CRN2 relay immediately cut out with above error and OVC red light on the drive.
Other axes seemed fine.

I would appreciate if anyone can help me on the above problem

[Al_The_Man]

Try feeding the motor armature only with a source of DC such as automotive battery.
See if it turns OK both directions smoothly and check current.
Al.

[kalawa]

Thanks Al for your prompt reply.
We put on a 12v car battery and onto pins C & F and then D & G on the armature receptacle but no rotation noted. This is after supplying power for the brake.
You mentioned 'armature only', are we doing it correctly I wonder going through the pins?

[Al_The_Man]

What is the MS number of the motor receptacle? 18-10 insert?
check for resistance, IIRC it is normally A & B pins.
Al.

[kalawa]

part no. on receptacle is JAE MS3108B28-20S-ZN, with 10 bigger size pins and 4 smaller size ones. From electrical dwgs pins C&D are for 2 off YA1 leads, and pins F&G are from 2 off leads YA2 from Y drive to motor.

Resistances are C - F =0.8ohms; C - G = 0.8 ohms; D - G = 0.8 ohms; A - B = open

Thanks in advance for your help

[fanucman]

omg.. dont put any battery on the motor it isnt going to help you..

get a volt meter remove the yellow cap and measure the resistance across the tach.. its mots likely the problem.. you need u see 100 ohms.. if its more than 10% out of spec replace it.. inspect the com, make sure it is clean.. if not use a eraser to clean off the carbon build up.. also check the brushes on the motor them selves..

[Al_The_Man]

C&D are one connection and F&G are the other armature connection, so this is where you apply armature voltage, either between C&F or D&G.
If you have the brake picked up, it should turn with a voltage applied, this may be where your problem is? is the armature free to turn when the brake is picked up?

omg.. dont put any battery on the motor it isnt going to help you..

.

I don't necessarily agree with this comment, do you want to elaborate?
I have been using this method for many years on the Getty's/Fanuc motors and others to do a simple basic test.
Al.

[fanucman]

well the other stuff i listed is just a better way of troubleshooting this problem that's all..

[kalawa]

we have gone with the car battery,remove the brake and the motor turns ok....phew!! now we are trying to re-set the brakes again and do another bench check since it appeared intermittent when last tested...
- break resistance 170 ohms.
thanks for the ideas and will keep you posted

[kalawa]

re-set the brakes(R=170 ohms) connect 100vac to break rectifier(with a 32A circuit breaker), heard the break move, then rotate armature spindle cw and it was fine.

But upon turning ccw, the circuit breaker opens and break resistance measured opened. It appears that the only way to get some further tests done is to remove the breaks and go through the same process again.

But, why would the armature orientation have anything to do with the brake circuit? We are removing the brake currently to check on wire shields but i would appreciate some theories behind this anomaly and suggestions on a quick and cheap fix.

Thanks in advance.

[Al_The_Man]

I would set up a separate supply for the brake, or is this what you are doing and the breaker trips?
If the brake is the tripping the breaker, it sounds like it may have ground on it.
Are you turning the armature manually or under power when the breaker trips?
Al.

[kalawa]

Thanks Al. We only supplied power to the brake and turned arnature by hand when the breker tripped. The brake leads were found squashed and bare wires exposed, were repaired,power supplied to break and armature was turning cw and ccw, by hand.
But when fitted to the machine and run by the machine control, the motor turned cw only and tripped with alarm SV011 when turned ccw.
Now we are removing the brake again to see if we can do more bench checks on it.

[gbowne1]

Interesting. Any more updates?

Greg

[kalawa]

have been away on business and just had a quick look at the machine today and it would not start at all....will have to sort out this problem first and will get back on the servo motor

[Khalid.Ins-Tek]

Hi

12Volts auto battery,remove the brake and the motor will ok.

[kalawa]

As stated earlier the motor turns ok both ways with auto battery but only cw when moved by machine controller. But now our machine PC would not even get ready for start i.e only the first pg appears with no mag switches coming on like before when powering up.
It is getting a little complicated for me and with minimal troubleshooting time on the machine I would highly appreciate all the help I can get. The machine has been down for quite a while and I do not have fanuc technicians at hand here in China who know classic old machines like ours.
Thanks in advance.

[Leblondmakino]

Hi, Have you checked all the motor connector cables for faults..sounds simple but you could have a loose wire on the Fanuc plugs on the motor .

Also check the the encoder for faults on this axis.

[Al_The_Man]

It is essential to have the electrical control prints for trouble shooting, especially where nothing is picking up initially, you need to check the status of the input unit, this is a small board/unit that monitors start up.
Do you just get the IPL menu screen?
Also, what is the indication on the 7 segment display (if you have) on the mother board?
Al.

[kalawa]

This machine is getting very annoying......now it wil start and we did not do anything to it. The errors are still the same SV013-Improper V-Ready Off alarm and red light on OVC on the Y axis velocity control. This was after the motor was turning freely cw & ccw using the machine control without load.
So we are back to square one. We had a techo from another comapny to have look and suggested we twigged the Y axis voltage regulator on the velocity PCB. Having no proper literature I am reluctant to allow this to be carried out and may cause bigger problems.

Al - what is an IPL (only used to illustrated parts lists) and which start unit are you talking about? Should I take pic to help identify to me?

I would appreciate if nay other ideas, suggestions and manual references etc that may help me identify this problem.

Thanks

[Zoner]

Sorry if I'm up the wrong branch, or even the wrong tree! Just trying to help in general since others are helping me with my problem too.

IPL = Initial Program Load. It's an IBM terminology in case you want to know this.

I'm not really clear from your post if the breaker is tripping when power is only supplied to the brake, and the motor is not energised? And also happens when you drive the motor with an external battery, so it is not connected to the machine circuits?

Is the breaker for the motor, or for the brake?

Is it for both the motor and the brake? (odd!)

Or is it one of the main breakers back from the motor and/or brake breaker(s), that feeds several parts of the machine? If so then those breakers are sometimes RCD/RCS type (Residual Current Detecting/Sensing, fast-trip safety breakers) and will detect any small earth leakage and trip to save the operator - (who cares about the machine, eh?

If it's for the brake only, then the motor is probably not to blame unless it is shorting the brake power supply - can it do that?

If it's the motor breaker then...

Do you have another identical motor on the machine?

If you do, put the good motor in this circuit just for testing - don't put the suspect motor on the good circuit first, in case it is faulty and might damage the good circuit.

Then you will see if the problem is really in the circuit or just the motor is damaged.

One thing to remember is that circuit breakers also get sensitive or faulty, it is worth swapping it temporarily with another of the same rating in your machine, or get a new similar one! I have wasted some hours several times in my long life assuming the breaker was never going to be bad - they were, even the great big contactors!

This is just a thought, I assume your motor has two commutator rings, being a dc motor. So just cleaning it well especially between the rings, should do the trick, but you may have a piece of the coil wiring loose inside that just touches the armature when in reverse? Tricky but possible.

In my past experience with ac motors, which have segmented commutators, when you abrade the motor commutator you will need to lower the level of the insulator material between the segments by carefully cutting it down slightly (about 0.1-0.2mm) below the level of the bronze segment with a square scalpel or modelling blade. Ensure you clean the sides of each gap too, and clean off any burrs on the sides of the segments that might be caused when you remove the insulating material. And then clean the whole assembly with alcohol, be sure to remove all scrapings and powder.