[bob1112]

Powering up a machine that has been down a couple yrs. I am fighting with some control issues which would not allow to bypass estop and I needed to know the servo amps would kick up so I manually fired the contactor for the amps. All 3 amps came up with "healthy" status lights but the noise they are making sounds like trouble to me but I am not familiar with the drives.

This is on a mid 90s machine. Drives are all AC. The only time I usually hear this ominous sound is power supply trouble indicating either a power supply is unstable or over driven. The lights say they are fine but I only powered them for 30sec or so. The amps receive 230VAC power so there would be DC PSUs in each amp. I am curious if some servo amps make this squealing sound? I think the last time I heard it, it was my office monitor and I replaced all the caps in it and good as new now. I don't want to make a mess of the amps if they are going to explode!

Any thoughts?

[Al_The_Man]

What drives? What motors? it sounds as though you brought up the power to the drives without being under control?
What make/model of machine?
Al.