Problem- Some query's about Fanuc ac spindle drive fault

[Stotschek]

I've got a fault on a fanuc ac spindle drive model A06B-6044-H018 control board A20B-0009-0532 on an okuma lb15 lathe the error code says that its "Radiator for power semiconductor overheat" lights up as soon as the mains are switched on. I'm curious as to how the drive senses this I'm assuming a thermistor on the heat-sink, I'm making an uneducated guess that the sensors faulty as the fault kicks in from a cold start. Do these drives use any other methods of sensing for this type of fault maybe fan trigger ect?

Regards

Karl

[cnc2149]

The amplifier has a normally closed thermal switch mounted in the chassis. The wiring of this thermal feeds up to the printed circuit board through connector CN5, pins 6 and 7. If the thermal has opened, you should measure approx 20VDC across these pins. You can also detach the printed circuit board and do an ohm check across pins 6 - 7 (reading into the chassis). If it measures open when cold, then the sensor is likely bad.

[Stotschek]

Thanks for the info mate, I'd identified the thermal switch screwed in the heat sink earlier but did not know if it was normally open or closed, or if was a thermistor. I did a quick continuity test at the time and it was conductive, and left it at that. Had a bunch of problems with the cpu cards that need to be fixed as well and left it at that. There fixed so I'll start concentrating on the drive this evening.

Thanks again

Karl