VAC III Changeover

Hello Guys!!
i asking some advice with the LT25-M
The problem is, when i start the machine i get
a alarm related to the Cicle to the Changeover, of the Low speed
Relee (not is actuated).
i double check the driver side off this relee and discover is working fine
... well i suspect over the Relee atached to the PCB in the VAC board
and discover this and the driver transistor is fine. (so i suspect to the logic
in the vac board)

Anybody have a idea how i doing further testing to pinpoint the faulty circuit?
any help is wellcome.

thanks in advance


juanjo

Try swaping the auxilary N/O contacts on the contactor itself. There should be a spare one on the other side of the large contactor. This is an input back to the SPU to tell it the change over has come in.

I've had a couple of these auxillary contacts fail now and the quick fix is to swap to the spare N/O contact.

hi, i Try it, and post the results....
thanks by the support

Juanjo
:)

hi againg.

Yes i try the "feedback" contact at changeover relee, and it was jamming, the spare one also is equal, so i disolve a can off contact cleaner,and actuated several times, problem solved!!!

i are amaizing, when we get this alarm, also we discover a rolled piece of paper inside a toroid, write by hand "VAC Changeover Error" ready to sent Okuma as the Technician looking this machine not test the whole system. of course in Okuma the VAC may return Fine, but with the Problem unresolved in the machine.
The Amaizing, is this machine was at a GM plant, so i suspect may be a couple of guys ready to lift alarms in the machines and this one is a very simple to solve very Hard to isolate!!!! a good one to test a Technician!!!


Thanks!!!!

but i now get a alarm related to the Spindle refrigerator unit, i check and both units not working, so it may be a fuse or another minor issue, i check later it.

Juanjo