Torq Cut Tool Changer Thyristor Failing

[Mark McDade]

First, apologies - I know there were some old threads on this subject but I can't find them anymore...

I have a Torq Cut 22/DX32 VMC. Every few months, the thyristor (Grayhill 70M-OAC5A) which controls the "out" direction of the tool changer fails on the LC-TLAUF board. I've now replaced it three times in two years. Any ideas about the root cause of this problem so I can eliminate it?

TIA,

Mark

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[machinehop5]

...possible failing Solenoid Coil drawing to much current (amperage) for the relay to handle. Looks like that 70M-OAC5A Relay is rated 3 amp
https://www.digikey.com/en/products/...M-OAC5A/180934

[CitizenOfDreams]

You should definitely check the coil and compare its DC resistance with a known good one. Also check if the "IN" relay gets hotter than the "OUT" relay during operation.

Another possible reason is an intermittent short in the wiring.