Steppers run to limits when mains switched on. REPAIRED

[triac]

Hi All
My Orac has been working in std form for the last 2 years without problems, now when the power switch is turned on both steppers run until the limit switches are operated, this happens without any program being in the machine memory and before the small VDU is working.

Seems like a signal is being sent for the movement and I did suspect a relay is welded up, but
this seems not to be the case as the limits are operative, so far unable to find the problem.

Anyone experienced a similar problem ?
Thanks in advance for any help.

Emgee

[angel-tech]

check for oil on the controller cards.

[Martin]

Remove the cover from the light switch & remove any swarf.

[triac]

Hi Martin

Thanks a million, removed cover to find brass chips at bottom up to light connections,
blew them out and all is back working. Brass wasn't the last material used in the lathe so for some reason there was a delayed action !!
Thanks also to AngelTech for advice.

Rgds, Emgee

[Martin]

Great. Glad you are back up & running.

[angel-tech]

i'm curious, so the brass swarf was shorting the ac supply to the light. Did this cause the controller power supply to fail ?

[triac]

Hi angel-tech

No fuses had to be replaced and the steppers moved as stated so the answer i believe must be a no. Incidentally the spindle motor wouldn't start during the time when there was a fault with the steppers running to the limits.
I cannot be certain how high the chips were within the light switch case because when moving the switch cover away at the top, before pushing downwards to clear the switch,some chips fell away.
When cover completely removed the 2 mm lip at the bottom was heaped up to the bottom of the conductor entry to the connection, some chips were actually lying around the onductor so I think it is safe to say the chips were shorting between the 2 connections.
It is difficult to know the resistance of heaped brass chips but it must be quite low, enough to cause the problem I experienced but high enough to prevent a lot of current and hence rupture of the cct fuse.
Did think about taking a picture but was impatient to test the lathe function.

Any ideas on the axis display zeroing function I asked about many months ago ?

Rgds, Emgee