Originally Posted by
SEA_INC
I recently moved my shop to a new location, during the move my SL20 shifted on the truck. Though no damage was apparent at the time, we got it set up in the shop, leveled, wired, phase checked, spindle, turret, and tailstock alignment checked, everything was within spec, though the spindle centerline offset changed by ~0.015".
We ran some test pieces, and it cut to spec.
I had maybe 10 hours on the machine since the move, and had just finished a boring operation, as the turret was returning to G28, and the spindle was slowing from ~2,200RPM (G96) we heard a BANG! and the machine shut off.
I could see the 50A breaker on the wall had tripped.
I opened the back panel and looked for melted wires or anything burnt. Though I could smell the faint aroma of magic smoke, I couldn't locate the source.
I carefully worked my way from the breaker to the Vector Drive, checking voltages, it was the normal 209 - 210.5, and 230 off the transformer tap going to the Vector Drive. Though both the Phase Pass and Phase Fail indicator were lit.
I shut down the power and rechecked all the connections, everything looked good. So I powered it up again. The Phase Fail indicator went out.
I probed the DC BUS and it read 0.0V.
I checked the Alarms, and came up with:
903 CNC MACHINE POWERED UP
160 LOW VOLTAGE
123 SPINDLE DRIVE FAULT
I cleared the alarms, and only ALARM 123 SPINDLE DRIVE FAULT came back immediately, even after multiple resets.
I checked the Vector Drive and the POWER ON and FAULT LEDs were lit, the HIGH VOLTAGE was NOT lit.
I powered everything down, ate lunch, and then disconnected the Servo Drives from the DC BUS, powered it back up, and this time the POWER ON, FAULT, and HIGH VOLTAGE LEDs let up, though the HV was dim.
I probed the DC BUS and it read 18.0V, checked the DIAG page, and it concurred.
I powered it down, waited for the HV LED to go out, then disconnected the VD, I ran resistance/diode tests on the Spindle motor, Servo Drives, and Regen coils, everything seemed to be in spec.
I pulled the VD and threw it on the bench, pulled the cover, and started looking around.
I couldn't find anything burnt, melted, or visibly damaged, except for the off-board resistor that runs between the +HVDC on one of the MG150J2YS50 IGBTs and port J5 on the top board (which looks like it feeds Q4, a G7N60C.
The tubular ceramic resistor doesn't look burned, but it did melt the epoxy near the middle, and cracked the ceramic cleanly. I can't read the numbers except:
"~00 [crack]" (possibly 100)
"1A" or "10" [crack] unreadable character or two"
Going by Tayfun's Schematic, it should be a 100ohm resistor, looking through the threads some say its a 100ohm, 50W. I tried searching for a replacement, but I could only find 100ohm/50W resistors that tend to be ~4" long, this one is 2.00"-2.050" OAL and ~.600 OD
QUESTION-
Does anyone know the spec for a replacement resistor? would a 100ohm/25W-50W (seems to be the correct dimensions for the one that was in there) work without burning out?
Any guesses to what caused the resistor to self-destruct and the breaker to pop? I thought it may have been caused by feedback and failure of the Regen circuit, though I would think that much of an energy dump would have fried a lot more.
Due to the move, I can't afford a replacement Vector Drive, nor a Refurbished unit. If I can get a replacement resistor, then go through step-by step, probing as I reconnect it, I'm hoping I can get my machine back up and running, so i can finish some work and then buy a replacement/backup.
Thanks,
-John