6SN1145-1BA00-0CA0 Pulsing #4 yellow LED - 200V-500V swing in DC Bus. HELP!

I have a production machine down right now. 400VAC input... DC Bus flucuates. Symptoms are when all enables are finally engaged, the I/R module6SN1145-1BA00-0CA0 has 600VDC and shows a luminating active #4 yellow LED for a short period of time (2-3 seconds), at which point all LED's are off for approx 20-30 seconds while DV voltage drops imediately to ~200V (I only watched it twice) and slowly climbs up to ~500V, then yellow LED again for 2-3 seconds and cycle repeats.

The rectifying diodes appear to bias properly.... so must be capacitors???

Any further testing or conclusions I can make?

Thanks in advance.

Yes this is a CNC controlled system. Unfortunately there are no alarm or error codes to reference. Simply a pulsing DC Charge link yellow LED that corisponds to a fluctuating DC bus.

I did find that link in my original searches.

The rectifying diodes would appear to operate correctly by biasing them with a multimeter. I can power up this module separately at next oppertunity. If the symptoms are still present, this meens this module is bad... if the symptoms go away, where do I go next?

Regards,

Know of a source for parts relacement FETs or contactor? not sure if I can find a drop in board replacement....

Thanks again for your assistance.

All signals on the simodrive system have been checked, all active.

I assume the PLC is not reading one of these signals.

So to access the PLC status in thesinumerik 805, a password is required. Once found and entered, I get a screen with a single item of 'garbled' characters and the system freezes. (see the last images) Talking with the operator, he has seen these kind of characters occasionally in the past. A hard reboot of the system is required to get operation again.

Also worth noting is 'garbled' characters on the LCD of the simodrive control module. This LCD has been flashing betweed P-000 and the characters in image 1 (Did this with the initial IR module with burnished contactor and blown FET's) . The sequence of other images were taken within about 50 seconds and happend shortly after the password was entered to attempt to get into the PLC status.

For a short period of time, the LCD also displayed F09 with three - , indicating further faults, but that was a short term occurence. Does not display this now.

Please see attached pics.

After seeing this, my thoughts are, corrupt memory/ram, or communication errors?

What is the best diagnostic/corrective direction I can go with this machine?

It is at least somewhat operational, but I am sure it wont be for long.

Thanks in advance!