TM 10-4610-232-34
Table 2-1. Direct Support Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
15. Cartridge filter plugged light is on at a differential pressure less than 12 psig or, is not on and differential pressure greater
than 20 psig.
Test cartridge filter differential switch (PDSH3) for accuracy. Disconnect P24 (REF: Interconnection diagram FO-2,
Sheet 14) from the pressure switch panel. Disconnect the pressure sensing lines from the switch. Remove the cover on
the switch and tag/remove the wires from the pressure switch. Check for internal water leakage. Set a multimeter to the
Ohms x 1 scale and attach the leads to the switch terminals that the wires were on. Connect a dead-weight tester or
another known calibrated pressure control device to the switch high pressure (or inlet) port. The multimeter should
read zero resistance with no pressure on the inlet pressure port. Slowly apply pressure to the switch. The switch
should open on an increasing pressure of 14 to 16 psig.
(a) Replace the switch if there is internal leakage (para. 2-27).
(b) Adjust the switch to the correct setting if it does not actuate as described above. Remove the
adjustment cover and turn the adjuster clockwise to increase the actuation point, counterclockwise to
lower it (para. 2-29).
(c) Replace the switch if it cannot be adjusted (para. 2-27).
(d) Check the accuracy of the gauge that led to this malfunction if testing the switch reveals it is okay.
16. Feed pressure low switch does not work. (Ref. Schematic diagram FO-1, sheet 9, schematic lines 917-918).
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
NOTE
This switch is set to open at 5-7 psig decreasing pressure. It closes at 5-7 psig increasing
pressure.
NOTE
Refer to malfunctions 17 and 18 for additional troubleshooting.
NOTE
Be sure feed pressure is at zero before troubleshooting.
Remove connectors P12(REF: Interconnection diagram FO-2, Sheet 15) and P11 (REF: Interconnection
diagram FO-2, Sheet 14) from the control panel. Check for 110-120 VAC across J11A and J12J (REF:
interconnection diagram FO-2, Sheet 9).
If voltage is not present, go to step 7.
Check for continuity across P11A and P11K.
If the continuity check is okay, go to step 3.
If the continuity check is not okay, go to step 4.
Remove the cover from PSL4(REF: Interconnection diagram FO-2, Sheet 14) and insert a non-metallic tool
into the switch arm. Apply light pressure until the switch transfers to the closed position. Check for continuity
across pins P11A and P11J.
If the continuity check is okay, go to step 7.
Remove connector P24 (REF: Interconnection diagram FO-2, Sheet 14) from the switch panel. Check for
continuity across J24A and J24J (REF: Interconnection diagram FO-2, Sheet 14) with the switch set as in step
3. Remove the tool and check for continuity across J24A and J24K.
if the continuity check is okay, replace/repair the cable between P11 and P24 (para. 2-18).
Refer to the electrical Appendix E-1. Check continuity, point-to-point, from J24A to J24K.
(a) Repair any loose or damaged wires (para. 2-28).
(b) Replace/repair connector J24 if faulty (para. 2-28).
(c) Replace PSL4, if it shows an open circuit (para. 2-27).
Refer to the electrical schematic Appendix D. Check continuity, point-to-point, from J24A to J24J with the
tool inserted as in step 3.
(a) Repair any loose or damaged wires (para. 2-28).
(b) Replace/repair connector J24 if faulty (para. 2-28).
(c) Replace PSL4, if it shows an open circuit (para. 2-27).
Change 1
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