I recently purchased a Kuraki KV-700 VMC.
The machine has a Fanuc 11M control.
The spindle drive top board is A020B-0009-053

I have the following alarm when I start up the machine:
"EX050 Spindle Volt Excess"

Kuraki manual says:
"The D.C. Voltage of the SMDU power unit is abnormally increased"

So I opened up the back cabinet and I see that the diagnostic LEDs on the spindle drive top board are lit up 8, 2, 1 which I have discovered is Fanuc code 11 "DC Link Voltage High".

Through searching this site and the net, I have determined that there seem to be four possible causes:

1) Possibly bad fuses on the spindle driver? Which ones and where are they located? What would cause these to blow?

2) Possibly a bad Spindle Driver. I've read about some bad transistors. Which ones? What is the test procedure for these?

3) Possibly my power is uneven between the phases. I have a nearly new Temco 7000-21 phase converter running on 208 volts from a buck-boost transformer. I have also tried the machine on direct 240 (no transformer) with the same results. I have noted that the voltage between L1-L2-L3 varies by as much as 8-10 volts between the pairs of legs, although it doesn't fluctuate more than 1 volt. Could this mismatch between the phases cause the alarm I'm receiving?

4) The machine is and has been in a somewhat cold / humid environment here in NW Washington state. It is in an unheated shop for the time being until the heat is installed. I read a thread that suggested that some Fanuc drives may not function correctly when the conditions are cold and high humidity.

Any and all help is appreciated greatly. I have been away from CNC machines for almost 10 years, and have to re-learn a lot of things.