[mogwopjr]

Hello there,

I've spent a bunch of time trying to troubleshoot this but I think it's now time to phone a friend, or maybe 50/50

Mori Seiki TL-3A lathe
Fanuc 5T control
Mitsubishi Diarol 18KW DL-SBZ half wave spindle control unit

Here is what I was told before the failure occurred:
the operator was running a program to turn some parts, and the spindle was working fine, no obvious issues and all of a sudden just kicked a breaker on the Spindle Drive unit in the lathe. The unit had been used very little in its new location but was functioning OK till it just stopped...also the Fuse had been blown on L1

Turns out that the phases were not connected correctly ( the lathe was recently moved from another shop to this location ) we got that resolved but the troubles did not go away. I'll list the symptoms
Turn machine on, home, zero, start spindle.
Spindle turns for a couple minutes and contators go nuts and machine goes into fault.
current fault lights are IOC, Zero Speed and sometimes Breaker Trip. (L1 breaker trips sometimes or blows L1 fuse still. After replacing SCRF we stopped blowing fuses)
Spindle spins to a stop - obv no brake engaged when this happens.

note: when the spindle is up to speed before everything goes nuts, the Undervoltage lamp is lit

I found the SCRF thyristor (SCR) was bad so I replaced it.
Found the left fan to cool the thyristors was not functioning, that's been replaced now
All of the thryistors test OK at this point
Signals on the control board look OK on the oscilloscope per the DL-SBZ repair manual.
Voltages check ok per the repair manual

Manually starting the spindle and stopping results in same condition as performing M03 S800 and then M05.

Symptom is still the same - I just cant figure this puppy out and I'm at a loss. Does anyone have any insights on this thing?

Here's a link to the video of the start and stopping with the IOC alarm at the end, kind of dark but I can explain LED's if needed. Lets see if this video link works https://youtu.be/oHLumXW18Ng

Thanks in advance for any thoughts or brain power put to this thing, I've probably spent 5 days scouring the manual and schematics and troubleshooting this issue.

[mogwopjr]

I should also say that I'm not sure if this should go into the spindle subforum or this one. If it would be better over there please let me know and I can move it. I'm not entirely convinced its limited to the spindle or the control yet so please let me know.