Fanuc AC axis control top board p/n is A20B-1000-0560/rev 11F
Here is the problem; I have this drive hooked to a lathe C axis red cap model 0 motor which makes high pitched noise and gets really hot at idle. I have meggered the motor and it seems fine, but I doubt the hundreds of megaohm readings I get. If I rotate the shaft by hand while checking between phase and chassi I get infinity on a good fluke meter, so at least there is a chance the motor is ok.
I have the maintenance manual for the control, a 10T and the maintenance manual for the valocity drive, but none make any recommendations for testing that the variable resistors are set up correct.
I bought the lathe recently so I have never had the motor run ok. I know the company who sold it have not used the C axis for the last 10 years. Maybe because they had the same problem. So I have no reference for the settings which could be way off. The manuals only suggest 40% on RV1 which is gain and this is where I have it. RV4 is 5V fine adjustment and I did lift this a little to get to exactly 5V.
I read somewhere that RV2 should be set for 0V while checking across Check pin 1 (0,687 * velocity command voltage) and CH3 (0V), so I noted that it was originally set at -0,11V, then I set it to 0V. This did not make much difference so I set it back to -0,11V. Next I checked the setting for RV3 on the X axis board ( same motor and drive ) which works fine and copied the 50% setting to the C axis. Did not make much difference either, but I played with it a bit. At one point there was actually a bit smoke coming from the C motor, but I dont know if this was due to the time it had been powered up or my attempts to set the RV3! There are a few more trimpots, but as the revision number is not the same between X and C boards I really have no clue and dont want to mess with them. I hooked up X motor and pulse coder from the C board and it sounded fine. next I hooked the C motor and pulse coder to the X axis drive and it was still noisy. So this would suggest that the settings on the C drive is at least semi-ok and the C motor or pulse coder is bad.
Still I would really like to know if there is a better approach to setting all trim pots the way the really SHOULD be set? Fanuc only writes "RV2 - RV4 have been adjusted before shipping"???
The best result I got from playing with the trim pots was to stop the noise while the motor is powered, but not mounted to the axis. If I then force the shaft radially by hand the squeeling noise comes back. Some time it stops when I stop forcing the shaft and sometimes it doesn't stop. In any case as the weight of turning the C axis is enough to make it squeel it always does when hooked to the axis. If I leave it squeeling for a few minutes I get alarms as expected.
I would like to try the X axis pulse coder on the C motor, but want to wait until I know the C top board is set up right.
I just bought a scope if that is needed.
All the best,
Andy