[settingbur]

I have a F-20 that runs great for until s.spindle thermal alarm goes off. It can run all day and not go off or it can run 3 cycles and go off or any variation of cycles. After powering down the alarm may go off as soon as powering back on. Spindle does not feel hot to touch. Could it be as simple as loose connection or has anyone else ever encountered this problem. Thanks

[ProProcess]

...Spindle does not feel hot to touch...

You say that it does not feel hot to the touch, but that is not (necessarily) what the thermal alarm means, its a voltage thing.
I've not ever run an F series, so I'm not sure about how the overload protection is implemented.
The fact that it fixes itself, without intervention i.e. you reseting a switch may mean that you have a loose connection or a short somewhere.
A with the power on, you can CAREFULLY move all the wire and connections to see if you can generate the alarm.
This would indicate that a cable needs replaced.
Aside from that I would (as usual) suggest, that you contact Citizen.
They do have some employees that are still in place since the F series, and they may be able to help.
Too, a look in the maitenance manual at the overload circuit may reveal what points of inspection are required to properly troubleshoot your issue.

Good luck chasing your "ghost"

[settingbur]

Thanks for your ideas of where to start looking, will post here if I find the solution after finding that bloody "ghost"

[MX1]

What control does it have, I have several f-12's and f-16's with Famuc 3tc's and usually when a problem is intermittent like that it's a circuit board issue. If you have another machine to swap parts with you can save yourself a lot of time and money and issolate the problem.

I don't have any f-20's or any 12's or 16's with sub spindles.
If any of the sub spindle or axis motors have brushes, take them out and see how long they are and clean the dust out.

Check the wire harnesses, make sure they are tightly plugged in and that the covering isn't harded up and broken in one spot that keeps flexing all the time, the wires will eventually break in this area.

Be patient, these problems can be very hard to find and a guy on the phone who has never seen one of these machines isn't always much help. But sometimes they can send you in the right direction and find the problem.

Let us know how you make out.
MX1