I've been running a K2 router with servos (3.5A, 24V), a home grown PSU (26V, 99,000uF smoothing), and G320s for about 6 months now. I bought the drives 11 months ago.
I recently left them energised but idle for a few days (not by any means for the first time), and when I returned to them my servos remained in the position that I left them in, but the main fuse had blown on the servo PSU. I replaced the fuse, and immediately one of the G320s sizzled, glowed bright orange under its cover, and produced a plume of nasty dark brown smoke. I hit the mains power emergency cut off within a couple of seconds, but of course the damage was already done.
I think that the included photo shows the failed component clearly (the small upright rounded cuboid near to the large electrolytic). The board was a REV 7.
Unfortunately, my troubles don't seem to have stopped with one failed drive.
I swapped the Y axis servo on to the previously unused servo drive intended for the C axis, and reconfigured EMC2 to drive that as the Y axis. The motor remained dead, though the encoder was clearly working (I could turn the Y axis ball screw by hand, and after a fraction of a turn the ERR light would light on the drive). From now on I'll refer to this new G320 as the Y axis drive.
Not thinking clearly enough about what I'd observed, I decided to try the Y axis servo driven from the known good Z axis drive, and got exactly the same behavior as on the Y axis drive. Switching the set up back so that the Z axis drive drives the Z axis servo now gives the same broken behavior as the new Y axis: dead motor, working encoder.
The X axis drive and servo are both fine (they work together). When I put the Z axis servo on the X axis drive, that works too.
So now I have:
servo drive
X: OK OK
Y: unknown bad
Z: OK bad
I don't want to try the Y servo with the X drive in case it blows up the X drive too.
I have made the following measurements:
Z motor DC resistance ~= Y motor DC resistance ~= 1ohm
X G320
PSU ground to ARM + = 61kOhm
to ARM - = 56kOhm
PSU +V to ARM + = 3.7MOhm
to ARM - = 540kOhm
Y G320
PSU ground to ARM + = 5.1MOhm
to ARM - = 5.1MOhm
PSU +V to ARM + = 13MOhm
to ARM - = 13MOhm
Z G320
PSU ground to ARM + = OC
to ARM - = 5.1MOhm
PSU +V to ARM + = OC
to ARM - = 12.8MOhm
So, what now?
It looks like I have damaged the Y & Z drives, and something may be wrong with the Y axis servo to cause it. Does that sound right?
How can I find out if my Y servo has the touch of death?
How can I stop this happening in the future?
I've already learned two things:
- Don't plug and unplug servos while the power is on (I'd done that many times without incident, but I've not read the FAQ which says not to).
- Add per controller 20A FF fuses. I only had a 1A slow blow mains input fuse.
Mariss, which if, any of the drives should I send to you?
Any help apreciated
Leo