[nitrosnfr]

Need help with an old Miyano JNC-35 lathe.It's had a problem with the Z axis servo.Gets hot noisy bearings was replacing it with a spare we had around.
I put the spare in and now get the 401 alarm.I can move the machine in handle mode but not jog or zero return get alarm instantly.It has a Fanuc 0T control on it.
I tried to adjust the gain control on the pcb but no luck.
Don't know much about the machine,just try to do repairs and trouble shoot when asked.
Any help much appreciated.

[Abacus]

I ran a Fanuc OM that was getting a 400 alarm of some sorts. I read somewhere about adjusting the potientometers, but in the end found it was directly related to the amount of hydraulic pressure required to move the machine (too much/ not enough - bleeder not hooked up). Not sure if that helps at all but g/l!

[samu]

look at diag parameter no.720. You can get more info by that prm. i'm not sure it is 720 but i'll chek it tomorow.

[bmngator]

You might try checking the condition of the motor brushes.

[ckirchen]

I second checking the brushes. My machine would get trapped in a 401 loop (it couldn't get past powering up the servos no matter how many times the main breaker was powered off and on) at least once a week. I pulled the cap on the Y servo (based on the suggestion of another poster) and a big pile of brush dust fell out. Probably never opened since manufacture back in 1983. Now, i get a 401 once in a blue moon, and it always disappears after a power off/on cycle (knock on wood). In all fairness, it could be the Z servo, but I haven't checked it because it's buried inside the machine.

Chris Kirchen

[nitrosnfr]

Finally got back to work on that machine,rebuilt the Z servo put new bearings in it and had the armature turned and tested.It was shorted out, after it was turned and freshened up put back together with new bearings and all good now.Adjusted backlash with parameters and got it down to .0002 backlash.

Thanks for the ideas and help