TM 10-4810-232-34
Table 2-1. Direct Support Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
NOTE
When checking continuity in the power circuits it is important to watch the wire numbers
on each phase. Each wire is tagged identically on both ends, but in some instances, a #1
phase wire will enter the top of a starter or circuit breaker and come out the bottom of the
same device as a #2 phase wire. This is done to change the rotation of a motor so that its
associated pump will turn in the correct direction. Any two wires may be interchanged to
accomplish this rotational change.
(a) Repair any loose or damaged wire (para. 2-20).
(b) Replace circuit breaker CB2 (REF: Interconnection diagram FO-2, Sheet 10) if open on any phase
(para. 2-25).
(c) If an MS1 overload is open, replace it and continue troubleshooting to find cause (para. 2-25).
(d) If MS1 shows open on any phase, replace/repair it (para. 2-25).
(e) Replace/repair J20 if faulty (para. 2-21).
Step 4. Shutdown ROWPU and generator. Refer to electrical drawings in Appendix D. Disconnect the cable from the
ROWPU to the generator at the generator end. Check continuity, point-to-point, from the generator end of
the cable to the power distribution block (PDB) on each phase.
(a) Replace the main power cable if open on any phase (para. 2-18).
(b) Replace circuit breaker CB1 (REF: Interconnection diagram FO-2, Sheet 10) if open (para. 2-25).
(c) Repair any loose or damaged wires (para. 2-20).
(d) If the above checks have not revealed the problem, refer to generator troubleshooting.
3. Air compressor runs but hourmeter does not accumulate hours. (Ref. Schematic diagram FO-1, sheet 8, schematic line
825).
Shut down ROWPU and generator. Refer to electrical drawings. Check for loose or damaged wires to the hourmeter.
(a) Repair any loose or damaged wires (para. 2-20).
(b) Replace hourmeter if above checks do not solve problem (para. 2-24).
4. Air compressor runs but air compressor light does not come on. Light test okay. (Ref. Schematic diagram FO-1, sheet 8,
schematic line 829).
Shut down ROWPU and generator. Refer to electrical drawings in Appendix E and remove the #2A wire from pilot light
PL20 (REF: Interconnection diagram FO-2, Sheet 11). Check continuity, point-to-point, from terminal 1-46 to PL20
(wire #328) and from transformer T1(X2) (REF: Interconnection diagram FO-2, Sheet 10) to PL20 (wire #2A).
(a) Repair any loose or damaged wire (para. 2-20).
(b) Replace LTK1 (REF: Interconnection diagram FO-2, Sheet 14) if its contact is open (para. 2-23).
Normally closed.
(c) Replace PL20 if the continuity checks are incorrect (para. 2-22).
5. Air compressor motor starter (MS1) does not pull hr. (Ref. Schematic diagram FO-1, sheet 8, schematic lines 824-827,
control circuits; schematic diagram FO-1, sheet 5, schematic lines 518-520, power circuits).
Shut down ROWPU and generator. Remove the motor starter coil wires. Use a multi meter and check resistance across
the coil connections. It should be near zero.
Replace the motor starter if resistance is infinity (open) or zero (shorted) (para. 2-25).
6. Air compressor motor starter (MS1) pulls in but air compressor motor does not run. (Ref. Schematic diagram FO-1,
sheet 8, schematic lines 824-827, control circuits; schematic diagram FO-1, sheet 5, schematic Iines 518-520, power
circuits).
Step 7. Shutdown ROWPU and generator. Turn circuit breaker CB2 (REF: Interconnection diagram FO-2, Sheet 10)
Step 2.
off and disconnect connector P20 (REF: Interconnection diagram FO-2, Sheet 16) from the control panel.
Use a multi meter and check continuity across each pair of motor control contractors. Manually engage the
starter contacts during testing. The reading should be zero.
Replace the motor starter if any pair is open (para. 2-25).
Remove the contactor block from the starter and check for burned, arced over contacts.
Replace the motor starter if contacts are damaged (para. 2-25).
Change 1 2-63
