b. Turn off external DC power source to Vehicle Mount.
c. Disconnect Junction Box Power Cable from M88 Detector POWER connector.
d. Turn on external DC power source to Vehicle Mount.
e. Using multimeter and illustration, check DC voltage between Junction Box Power cable contacts A and B.
PIN B PIN A
JUNCTION BOX POWER CABLE PLUG
f. Does voltage read between +23.0 to +33.0 VDC between contacts A and B?
Yes: Replace M88 Detector (paragraph 2.8.5).
No : Do Step3.
Step 3. a. Turn off external DC power source to Vehicle Mount.
b. Disconnect Power Cable from external power source.
c. Turn on external DC power source.
d. Using multimeter, check DC voltage between external power source output + and -terminals.
e. Does voltage read between +23.0 to +33.0 VDC between + and - terminals?
Yes: Do Step 4.
No : a. Replace external DC power source.
b. If external DC power source cannot be replaced, notify maintenance supervisor.
CAUTION
NOTE
ARMY TM 3-6665-321-12&P
Change 1 4-17
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
Step 4. a. Remove cover from Vehicle Mount Junction Box by loosening four captive screws.
b. Check if input (top) and output (bottom) Power Cable connections are clean and tight at Junction Box terminals 9 (+) and 10 (-).
c. Are terminal connections clean and tight?
Yes: Do Step 5.
No : a. Clean the bare wire ends of the external DC power source cable (top row terminals) and Junction Box Power Cable (bottom row terminals).
b. Install the wires on Junction Box terminals 9 (+) and 10 (-).
Step 5. a. Connect Power Cable to external power source.
b. Turn on external DC power source.
c. Using multimeter and illustration, check DC voltage between upper row Junction Box terminals 9 (+) and 10 (-).
d. Does voltage read between +23.0 to +33.0 VDC on terminal 9 (+) and 10 (-)?
Yes: Do Step 6.
No : Notify maintenance supervisor. Power cable from external DC power source to Vehicle Mount must be replaced.
ARMY TM 3-6665-321-12&P
4-18
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
Step 6. a. Using multimeter and illustration, check DC voltage between lower row Junction Box terminals 9 (+) and 10 (-).
b. Does voltage read between +23.0 to +33.0 VDC on terminal 9 (+) and 10 (-)?
Yes: Do Step 7.
No : Replace Junction Box (paragraph 4.12.2).
Step 7. a. Using multimeter and illustration, check DC voltage between PIN A and PIN B.
b. Does voltage read between +23.0 to +33.0 VDC between PIN A and PIN B?
c. Reconnect M88 Detector and perform initial start.
Yes: a. Install Junction Box lid.
b. Connect to M88 Detector.
c. Perform initial start up (paragraph 2.9.3).
No : Replace Junction Box (paragraph 4.12.2).
ARMY TM 3-6665-321-12&P
Change 1 4-19
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
High voltage is used in the operation of this equipment. Death on contact may result if personnel fail to observe safety precautions when performing maintenance procedures on the M28 Power Supply.
Connecting or disconnecting energized M28 Power Supply AC Power Cable can injure personnel and damage the M28 Power Supply. Ensure external power is removed before connecting or disconnecting AC Power Cable to M28 Power Supply.
To prevent electrical shock, use extreme care when testing energized circuits.
NOTE
If M88 Detector gets power from Lithium battery or Vehicle Mount, skip Step 8 through Step 11.
Step 8. a. Turn off M28 Power Supply by unplugging AC Power Cable from power source.
b. Disconnect M28 Power Supply DC Power Cable from M88 Detector POWER connector.
c. Turn on M28 Power Supply by plugging AC Power Cable into proper AC power outlet.
d. Using multimeter and illustration, check DC voltage between contacts A and B of M28 Power Supply DC Power Cable.
PIN B PIN A
JUNCTION BOX POWER CABLE PLUG e. Does voltage read between contacts A and B?
Yes: Replace M88 Detector (paragraph 2.8.5) No : Do Step 9.
Step 9. a. Turn off M28 Power Supply by unplugging AC Power Cable from power source.
b. Disconnect M28 Power Supply DC Power Cable from M28 Power Supply 24V DC OUTPUT connector.
c. Turn on M28 Power Supply by plugging AC Power Cable into proper AC power source.
d. Using multimeter and illustration, check DC voltage between contacts A and B of M28 Power Supply 24V DC OUTPUT connector.
WARNING
ARMY TM 3-6665-321-12&P
Change 1 4-20
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
e. Does voltage read between contacts A and B?
Yes: Replace M28 Power Supply DC Power Cable (paragraph 4.11.2) No : Do Step 10.
Step 10. a. Turn off M28 Power Supply by unplugging AC Power Cable from power source.
b. Disconnect M28 Power Supply AC Power Cable from M28 Power Supply (AC MAINS INPUT) connector.
c. Connect AC Power Cable into proper AC power source.
Using multimeter and illustration, check AC voltage between contacts A and B of M28 Power Supply 110V AC Power Cable or 220V AC Power Cable.
CABLE CONTACTS FROM TO
110V AC A-B 108 VAC 132 VAC
220V AC A-B 208 VAC 232 VAC
e. Does voltage read within the proper range shown in the illustration?
Yes: Replace M28 Power Supply (paragraph 4.11.1).
No: Do Step 11.
Step 11. a. Remove power from M28 Power Supply 110V AC Power Cable or 220V AC Power Cable by unplugging AC Power Cable from power source.
b. Using multimeter and illustration, check continuity of M28 Power Supply 110V AC Power Cable or 220V AC Power Cable.
ARMY TM 3-6665-321-12&P
Change 1 4-21
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
c. Is continuity good for 110V AC Power Cable or 220V AC Power Cable?
Yes: Change M28 Power Supply 110V AC Power Cable or 220V AC Power Cable to a proper, known good power source.
No : Replace M28 Power Supply 110V/220V AC Power Cable (paragraph 4.11.3).
2. NONE OF THE DISPLAY LIGHTS ON THE M88 DETECTOR WILL LIGHT AFTER POWER ON.
Perform troubleshooting MALFUNCTION (paragraph 4.6, malfunction 1)
3. ONE OR MORE OF THE DISPLAY LIGHTS ON THE M88 DETECTOR WILL NOT LIGHT DURING INITIAL SELF-TEST.
Replace M88 Detector.
4. M88 DETECTOR WAIT LIGHT WILL NOT STOP FLASHING EVERY SECOND.
W
b. If Rain Caps are installed on nozzles, do Step 2.
c. Are Protective Caps removed from each nozzle?
Yes: a. Replace Inlet Nozzle (paragraph 3.4.1) with sealed spare part.
b. If fault is not corrected, replace M88 Detector.
No : a. Remove Protective Caps from Inlet and Exhaust.
b. If fault is not corrected, replace M88 Detector.
ARMY TM 3-6665-321-12&P
Change 1 4-22
Table 4-2. Unit Level Troubleshooting (Continued) MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
Step 2. Remove Rain Caps from each nozzle. Does WAIT light stop flashing?
Yes: Replace Rain Caps (paragraph 2.13).
No : a. Replace Inlet Nozzle (paragraph 3.4.1) with sealed spare part.
b. If fault is not corrected, replace M88 Detector.
5. M88 DETECTOR TAKES MORE THAN 10 MINUTES TO RESUME SAMPLING AFTER ALARM OR CLEAR-DOWN.
Step 1. Relocate M88 Detector. Did M88 Detector start sampling within 10 minutes?
Yes: Notify your maintenance supervisor about contamination at previous location.
No : Do Step 2.
Step 2. a. Replace Inlet nozzle (paragraph 3.4.1).
b. Perform Initial Power On and Self-Test (paragraph 2.9.3).
c. If fault is not corrected, replace M88 Detector.
6. M88 DETECTOR G AND H BAR DISPLAYS KEEP ALTERNATING BETWEEN SAME TWO LIGHT PATTERNS AND INITIAL SELF-TEST CANNOT BE COMPLETED.
BAR H1 BAR H8
Step 1. Shutdown M88 Detector (paragraph 2.10).
Step 2. Perform Initial Power On and Self-test (paragraph 2.9.3).
Step 3. If fault reappears, replace M88 Detector.
ARMY TM 3-6665-321-12&P
Change 1 4-23
Table 4-2. Unit Level Troubleshooting (Continued)
MALFUNCTION
TEST OR INSPECTION CORRECTIVE ACTION
7. M88 DETECTOR WILL NOT RESPOND TO CONFIDENCE SAMPLE TESTING.
Step 1. Obtain good Confidence Sample.
Step 2. a. Perform Confidence Sample Testing (paragraph 2.9.4).
b. Does M88 Detector respond to Confidence Sample Testing?
Yes: Replace faulty Confidence Sample.
No : Replace M88 Detector.
8. M88 DETECTOR ELAPSED TIME DISPLAY STAYS BLANK AFTER POWER ON.
Replace M88 Detector.
9. M88 DETECTOR DOES NOT SOUND DURING INITIAL SELF-TEST OR ALARM MODE.