Powered up my 1996, 15XT CNC 88HS mill with the servo coolant, option over this weekend after it had been setting in storage for three years. Everything worked fine before it was shut down for that period.
Unfortunately, some of the time it was in storage, about 4 months, it was subjected to cold temps (high 30’s to low 40”s), with rapid warming up in the mornings. So... the machine sweated.
((All, if you’re getting a divorce and have a shop at the home, MOVE THE MACHINES SOME WHERE ELSE!! (chair) The EX turned the power off to the shop (Even though I was paying the power bill. Thank you very much “dear”!) That… shut down the temp control system. In a metal building, that is not good.))
Anyway, I’ve spent a year cleaning and refurbishing the machine so it was completely dry. On power up the 50W, 10 OHM Resistor in the servo coolant control box blew.
I have a couple on order and on their way for replacement this weekend.
So I looking for your thoughts out there about doing the next power up.

Was it just a resistor self destructing or did I cause it? (Maybe cracked insulation and moisture in it? The end literally blew out.)

The coolant servo was unplugged as I was repainting the servo cover and motor/spindle shroud. Is there any reason it would have to be connected on power up? I wouldn’t think so.

Maybe the connector shorted when I unplugged it? I will check that first.

When I replace the resistor what other testing could I/should I do to the coolant servo power unit before putting power to it? Bench test it, ect.? It appears to have no other damage. I carefully inspected it under a scope. No burns, burn smell, or other suspicious looking marks, ect.

I would like to minimize the chance of having to replace the whole unit ( rebuilt $700 New $1100) assuming the resistor was the only damage.

Thanks for any comments or advice. (group)

Steve