Fault Message:

TRU 2 FAILED/TRU 2 FEEDER/WRG FAIL

Fault Code:

2460464DCP

Associated CAS:

ELEC SYS FAULT
(Advisory)

DC Power Center (DCPC) has detected a Transformer Rectifier Unit (TRU) 2 failure.

• DC Power Center (DCPC) (A63)
• DC Power Quality Monitor (DCPQM) Card 2
• Electronic Module 2 (EM2)
• DC Power Center (DCPC) Primary Logic Card
• Transformer Rectifier Unit (TRU) 2 (A74)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

If the TRU voltage indication on the DC synoptic page is less than 26 Volts, suspect a bad or a missing input phase from the AC Power Center (ACPC).

1. Swap the TRU 2 with ESS TRU 1.

   1. If system checks are good, replace TRU 2 and do close out.
   2. If fault remains, continue with next step.

2. Check for 115 VAC of TRU Voltage input phases.

   1. If voltage are good, go to step 4.
   2. If one or more of the phases are less than 115 VAC, continue with next step.

3. Troubleshoot the power input from the ACPC (AC BUS 3).

   1. If defects are found, repair defective wiring as required and do close out.
   2. If if no defects are found, continue with next step.

4. Check for 24 VDC at the DCPC input (stud T12) with load on the system.
   NOTE: An oscilloscope can be used to take the measurement in order to make sure there is no fluctuation of the DC signal.

   1. If voltage is good, go to step 6.
   2. If voltage is less than 22 VDC, continue with next step.

5. Perform wiring check between DCPC and the TRU 2 as follows:

   From	To	Result
   A74 (+)	A63-T2
   A74 (-)	Ground

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.

6. Swap DCPQM card 2 and the DCPQM card 1 in DCPC. Is the fault still present?

   1. If NO, replace DCPQM card 2 in DCPC and do close out.
   2. If YES, continue with next step.

7. In the DCPC, remove the three Primary Logic Cards, the DCPQM card 2 and disconnect connector P205 from Electronic Module (EM) 2.
8. Perform an EMI filter check by performing a continuity check as follows:

   From	To	Result
   P205-8	Ground
   P205-10	Ground

   1. If there is continuity, go to step 11.
   2. If If there is no continuity, continue with next step.

9. Check the resistance values of EM 2.

   From	To	Expected Result	Result
   J205-9	J105-8	2 KΩ
   J205-9	J205-10	15 KΩ

   1. If resistance is within range, go to step 11.
   2. If resistance is out of range, continue with next step.

10. Replace EM 2. Is the fault still present?

    1. If NO, do close out.
    2. If YES, continue with next step.

11. Replace DCPC.
12. Do close out.