T4 Stopping in flight

Dover T4 (duplex 5 stops) trapping people intermittently, takes about 2 hours of running to warm up and create faults. 54, 56 and 628 faults. Car tries to run 3 times then needs a TFR
I have changed
1. MC and BK contractors along with their Aux.
2. C1 contactor and Aux. (below drive main contactor)
3. Changed BKO, BKI, BK2, BK3, MCI, GL, WDPF, GL, DRDY, DE Modules
4. All of the 120v ice cube relays above brake relays.

No clue where to go with this car has been off line for 2 months now. Customer getting frustrated as well as me.

Had this same issue last week. Ended up being a bad IGBT. Make sure to use the heat sink compound when you replace it

Try replacing velocity encoder.

Looks like these faults are leaning towards losing one of the power supplies that feed the drive. Check all the power supplies on the rear of the controller for voltage and AC noise. Most likely your problem.

Good luck!

Looks like the 628 is the cause. I’ve never seen that one before though. How much AC voltage do you read in the bus? Could be the +/- 15v power supply, digital current regulator card, ribbon cable between DSP and current reg.

Check the bus voltage and check it for ac could be a bad cap bank

Jump the phase monitor and see if it goes away.

Did you replace the relay holders as well?

Change the DE Module...

I agree with jumping out voltage monitor especially if it is one of the orange ones. Possibly this is emergency stop from CPU shutting off very briefly. TKE had a bulletin to tap on the side of it with screwdriver handle to check for flaky internal connections/contacts. These have caused a great deal of aggravation. If that is your problem then replace the component. Also make sure you have good suppressors around contractor coils.