X-axis motor replaced -> problems

[FinnCNC]

Hi!

We have 1997 VMC-15XT with 88HS. Earlier today X-axis motor overheated smoked and failed. We repladed motor with brand new one but there seems to be problem. When machine is powered there is small noise and we found out that x-axis is drifting back and forth constantly very little amount. Also x-axis "amplifier balancing" reading is jumping from +3 to -12 (Y and Z are steady 0/1). I tried to swap X/Y amp cards but problem is still on x-axis.

Do we have faulty motor?

[Neal]

It sounds like either the encoder has a problem or the servo gain needs adjusting. When ever a motor or amplifier is replaced is a MUST to re-do the servo loop gain.

Neal

[FinnCNC]

Originally Posted by Neal It sounds like either the encoder has a problem or the servo gain needs adjusting. When ever a motor or amplifier is replaced is a MUST to re-do the servo loop gain. Neal

How does it happen? We have replaced motors in our fadals many times with just plug'nplay. But not this one

[Neal]

Each motor and each amplifier has their own distinct characteristics. The fact that you change one or the other without retuning only means that they were very close to the replaced item. Without the retuning you were not getting maximum performance from the system.

Neal

[little bubba]

The X axis, the one with the flex conduit floating around in the machine? The one that cracks occasionally, the one that is always moving, the one that is constantly coated in coolant and chips. I would give that very serious consideration.

A motor should not just start smoking, and I would make sure I knew exactly why it was smoking before throwing another one in, especially if the wires going to it are always moving.

[FinnCNC]

We had that cable replaced ½ year ago. I spoke with fadal service and they told to adjust loop gain / balance from amp card.

DC Amplifier
Adjustment
1) Enter the following program:
a. X-4. Y-4. Z-4. G1 F150. M49,M91.
b. X4.Y4.Z4.
c. M99P1
2) Press Auto, to start the program running.


Easy.


3) At the amplifier to be adjusted, use a small screwdriver and turn the SIG2
potentiometer until the monitor’s display of the appropriate axis reads the
following error: 595 - inch ballscrew / 302 - metric ballscrew.


We have inch ballscrews. AMP card didnt have SIG2 pot but there was SIG pot. It took amazingly many turns to reach numbers around 600


4) Press the SLIDE HOLD button on the keypad and adjust the balance of the
amplifier to read between 0 - 1.


Here is the problem, balance reading won't stay still to be adjusted, it bounces around from -6 to 14 constantly.


5) Press the START button on the keypad and the program will start again.
Verify that the following error is still 595 or 302.


Wont get stable reading here as well, reading is bouncing 550-650 when X is moving

[FinnCNC]

YouTube - Fadal VMC-15XT X-axis problem

YouTube - Fadal VMC-15XT X-axis problem

Crappy quality video about our problem. Suggestions? Tried again to swap servo amps between X and Y but problem stats on X-axis. Servo amp adjustments wont help.

[gaswiz69]

You need to check and/or replace your resolver pins at the motor. Chances are there is corrosion on the pins.

[alexacosta82]

did you get the problem fixed