TM 10-4610-232-12
Table 4-2. Unit Troubleshooting Guide (Continued)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 2. Disconnect the valve electrical connector P40. Check for 110-120 VAC across pins J4OD and J4OE
(Reference Interconnection Diagram FO-2, Sheet 15).
(a) If there is voltage present, notify direct support m a i n t e n a n c e .
(b) If there is no voltage present, go to step 3.
Step 3. Close the air block valve at the air manifold for the backwash inlet valve. Disconnect the air tubing to
the valve actuator. Check if the valve stem retracts into the actuator.
(a) If the stem retracts, repair the valve actuator by replacing the air control relay and solenoid
valve (para. 4-47).
(b) If the stem does not retract, or if it retracts with a jerky motion, replace the actuator (para. 4-47).
8. Backwash inlet valve will not close (s tern normal). BACKWASH INLET valve light on (Reference Schematic
Diagram FO-1, Sheet 7, schematic line 709).
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Check valve for actual position. Refer to “AUTOMATIC VALVES” general note.
If valve is closed, refer to valve light does not show correct valve position troubleshooting (malfunc-
tion 10).
Disconnect the valve electrical connector J40. Check for 110-120 VAC across J40D and J40E.
If voltage is not present, go to step 6.
Reconnect J40 and check for 110-120 VAC across terminals 4 and 5 on the valve.
If no voltage is present at the terminals, replace the valve cable and connector (para. 4-47).
CAUTION
Even after closing the block valve in the next step there will be 85 psig (586 kPa) air in
the tubing to the automatic valve. Slowly back off the tubing nut at the block valve to
relieve air pressure before removing the air tubing at the automatic valve.
Close the air block valve at the air manifold for the backwash inlet valve. Remove the air tubing from
the automatic valve and check that air is being supplied to the valve by opening the air block valve.
If air does not come out the tubing with the air block valve open, find the blockage in the air tubing
and repair it (paras. 4-24 and 4-68).
Check the wiring on the valve for damage or looseness.
(a) Repair any damage to the wiring (para. 4-47).
(b) If the wiring is okay, replace the air control relay and solenoid valve (para. 4-47).
Remove connector P14 from the control panel and check for 110-120 VAC across J14E and J14F.
(a) If there is voltage present, go to step 7.
(b) If voltage is not present, notify direct support maintenance.
Check for continuity from P14E to J40D and from P14F to J40E.
Replace the cable and connectors if faulty (para. 4-27).
9. Backwash inlet valve will not close (system clean position). BACKWASH INLET valve light on (Reference
Schematic Diagram FO-1, Sheet 7, schematic line 709).
Refer to the same problem in system “NORMAL” (malfunction 8).
10. Backwash inlet valve does not work. Light tests okay. BACKWASH INLET valve light does not show the actual
valve position (Reference Schematic Diagram FO-1, Sheet 7, schematic line 71 O).
Step 1.
Step 2.
Check the actual position of the valve.
Refer to the general note on ‘AUTOMATIC VALVES” and compare the actual position of the valve
to what its indicator light is showing.
No power. Check for damaged wires on the valve actuator. Check the limit switches on the valve ac-
tuator for damage. Disconnect the valve electrical connector J40 and check for continuity across
P40A and P40C when the valve stem is retracted into the actuator housing (valve open).
(a) Repair any damaged wires para. 4-47).
(b) Replace the valve limit switch (LS2) if the actuating lever is broken or if there is no continuity
across P40A/C (para. 4-47).
Change 1
4-55
