TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
NOTE
Ensure that all circuit breakers are set. Refer to Appendix l-1 for schematic diagram
and Appendix I-2 for interconnection diagram.
1. Raw water pump won’t start (SYSTEM NORMAL) (Reference Schematic Diagram FO-1, Sheet 6, schematic
lines 619-621 - control circuits, Reference Schematic Diagram FO-1, Sheet 5, schematic lines 532-537-
power circuits).
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Shutdown the ROWPU. Open the main control panel lower door. Check that the overload reset button
on MS3 (Reference Interconnection Diagram FO-2, Sheet 10) is in by pushing it.
(a) If the reset button is in, go to step 2.
(b) If the button is out and won’t reset, notify direct support maintenance to replace the overload
heaters on M53 and then go to step 3.
(c) If the reset button is out but resets when pushed, notify direct support maintenance to adjust
the door reset assembly for M53 and then go to step 3.
Leave the control panel door open. Refer to para. 2-19 and start the ROWPU in “SYSTEM NORMAL”.
Watch the indicating plunger on the M53 motor starter. It should pull in when the raw water pump is
started.
(a) If it does not pull in, or, if if pulls in but does not stay in, notify direct support maintenance to
troubleshoot the raw water pump circuits.
(b) If it pulls in and stays in, go to step 3.
Shut down the generator. Refer to the electrical schematic Appx. l-1 and interconnect diagram Appx.
l-2. Set multimeter to Ohms x 1000 scale. Check each lead, 3T1, 3T2, and 3T3 from the outlet side of
M53 to ground. The reading should be infinity for each lead.
If the meter reading is zero there is a short circuit, go to step 5.
Set the multimeter to Ohms x 1 scale and check for continuity between all pairs of leads; 3T1 and 3T2,
3T1 and 3T3, 3T2 and 3T3. Readings should be zero or near zero for each step.
If the checks performed in both steps 3 and 4 are okay, return the ROWPU to operation.
Check connectors J/P21, J/P22, J/P57, J/P58, and J/P59 (Reference Interconnection Diagram FO-2,
Sheet 16) for hose pins and for signs of arcing.
Replace any cable that shows damage (paras. 4-27 and 4-13).
Check continuity, point-to-point , from P21E to J59A, P21 F to J59B, P21 G to J59C, and P21 H to
J59D. Check each lead for shorts between phases and shorts to the ground wire. The reading should
be infinity for each check.
(a) Replace any cable or connector that shows open during continuity checks (paras. 4-27 and
(b) Replace any cable or connector that shows a short between phases or a short to ground
para. 4-27 and 4-13.
(c) Repair any hose or damaged wires in the outside junction box (para. 4-34).
d) Replace any MOV's (Reference Interconnection Diagram FO-2, Sheet 16) in the external
electrical panels that show physical damage or are shorted to ground from the power terminal
(para. 4-34).
Tag and disconnect motor leads (T1, T2, T3). Set multimeter to Ohms x 1000 scale and connect test
leads between each motor lead and the motor frame. Readings should be infinity for each step.
Replace pump/motor assembly if the meter reading is zero (para. 4-15).
Step 8. Set multimeter to Ohms x 1 scale and check for continuity between all pairs of motor leads, T1 and
T2, T1 and T3, T2 and T3. Readings should be zero or near zero for each step.
Replace pump/motor assembly if reading is infinity (para. 4-15).
Step 9. Check motor cable for continuity on each lead and for shorts between phases and ground.
Replace the cable if open or shorted (para. 4-15).
2. Raw water pump starts but stops when start button is released (Reference Schematic Diagram FO-1, Sheet 6,
schematic lines 619-620).
Notify direct support maintenance.
Change 1 4-65
