Originally Posted by Al_The_Man Systematic trouble shooting by voltage readings should pin-point the problem. |
I'm sure that is true, Al. I'll put a datalogger on my wishlist. I think that's the only way I'd catch the glitch, given that I haven't ever been able to cause the problem on purpose.
From the Tormach wiring diagram, the control voltage is 120V. I did find the datasheet for the contactor and it confirms that too.
Between the control transformer and the contactor coil, there is a fuse, the estop switch, a spindle lockout keyswitch and a belt guard interlock. As far as I can tell, all those components give good continuity with the power disconnected. On the machine control board, I'm assuming that a solid-state relay energizes the contactor.
There is one maybe related clue which makes me think it might be some kind of software issue. The first time the machine is powered up and the spindle energized, there is a several seconds delay between the contactor pulling in and the spindle actually ramping up. On subsequent starts, the delay is less.
The glitch hasn't shown up since my initial posting, so for now all is well!
edit: Looking at the wiring diagram, even the manual spindle start switch is low-voltage, so that is just acutating the (I assume) SSR on the machine control board. Any difference in operation must be either in the wiring on that board, or the Mach software. Or so it seems to me...
Randy