I've poured through the forums on this topic and I'm still having trouble. The machine is a Hitachi wire edm with 4 axis. 2 (x,y) are common fanuc a06b-h001's and the other two (u,v) are much smaller a20b-0006 drives.
Background. I turn the machine on and a series of contactors drop powering up various pumps etc.. one contactor powers the servos. It comes one for a few seconds and then drops off with a 403 alarm. I used to be able to power down and back up to clear it but not any longer. If I hit reset and run around the machine real fast (no helper) I can see the ready light blink on for both drives (x,y) then right back off. The u,v drives have no lights. I've read about the hcal lights and others but none of these are on.
So now I can hit "reset" and the contactor tries to power up but drops right back off with the 403 alarm. Once in a while for good measure it will give me a 400 alarm or both 400 and 403 at the same time. If I disconnect a servo cable it causes other faults.