[botha.y]

Hi guys,

I got one weird problem with a Makino milling machine with a Fanuc 0M control. The machine has 4 axis plus a spindle. The 3 axis servo drive display 0 (ready status), there is one dual-axis servo drive and 2 single-axis servo drives. The spindle drive displays - (not ready status, I think it will show 0 as soon as all references are completed and spindle is ready to move).

When moving the y-axis and z-axis, no problem, everything works as normal. The rotating A axis has to remain clamped as long as all other 3 axis have not be homed.

Now here is the issue: X-axis does not move whatsoever, but there are no alarm whatsoever being displayed. Furthermore, the currently displayed machine position does change while we are moving, but goes back immediately to the original value as soon as the X motion command is stopped. Parameter 504 (X-axis deviation allowed) is set to 10000, but even when modified to a very low value no alarms occur, it is as if the control knew that we command a displacement, make the number move on the screen, then realizes nothing moved, just goes back to the original position.
As for the encoder, as far as I know an encoder doing this kind of issue would very quickly display an X-axis displacement excess error as soon as deviation above what is set to parameter 504 is made.

As a quick note, when doing reference to X-axis, the value on the screen moves until it goes to OT+, then when it stops moving it goes back to original value, with no movements having been actually done. A simple reset removes the alarm.

Thanks in advance!

Edit: The only theory I could think of so far is a burned out servo motor. I've never seen a burned out servo motor before, don't know if it shows signs when there is deterioration (smell for example, there is no particular smell in this case) and don't know if it would give an alarm somehow. Thanks for any clues.

[botha.y]

Issue found. It was the axis board that was defective and needs to be replaced. Tested by swapping cables of m184 with M187 and of M185 with M188.
Cheers all.

[tc429]

some of those axis cards have socketed servo LSIs, might try just pressing them firmly into the sockets. some boards had poor quality sockets too- the corners crack after a few years and they lose connection- in a pinch, if the sockets cracked, you can wrap around the socket with something (have seen rubberbands/jb weld, etc) to tighten its grip on the springpins and keep it going till you locate another board...have seen quite a few that simply resocketing the chips helped

if its got newer style amps with the little honda PCR series plugs, they go bad almost daily at work anymore...when you swapped the cable did you physically swap it at the axis card or axis drive? if at the drive that cable might be a issue...often just plugging/unplugging a couple dozen times will clean the contacts and get it going again...I sure miss the old blue honda MR series plugs, have yet to see one fail.

[botha.y]

I physically swapped it on the axis card, the physical X-axis became the Y-axis and the physical Y-axis became the X-axis. I could move physical X-axis but not physical Y-axis anymore, so that's how I figured it was the axis card.
Thanks for the advices, although from what I saw when I opened the machine that card stopped working completely (it started by making one axis not move, then it swapped two axis when it should have not, then it just made a not ready alarm) so we'll simply buy a replacement card.

Cheers.

[botha.y]

As an indication for anyone who would have similar issues with their control, the problem was not the axis card. It was the parameters and/or the data diagnosis that was/were corrupted and needed to be reloaded from the original backup.

Cheers all.