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Page Title:
Table 4-3. Monitor Receiver Troubleshooting-Continued |
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|  TM 11-5825-270-23
Table 4-3. Monitor Receiver Troubleshooting-Continued
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
7.
INCORRECT CARRIER LEVEL READINGS
Step 1. If the reading is below the threshold level and there is no alarm go to step 2. If the meter reading is low but above the
threshold level go to step 3. If the reading is high go to step 3.
Step 2. Check the wiring to the meter (fig. FO-3). Check the resistance of the meter. Meter resistance should be approximately
50 ohms and the meter will deflect when the ohmmeter is placed across the meter (use the Rx100 or Rx10000
position on the ohmmeter to prevent damage to the CARRIER LEVEL meter).
a. If the meter requires replacement it requires direct support maintenance personnel (refer to chapter 5).
b. If no fault is found reperform the maintenance turn on procedure of table 4-2.
Step 3. Perform the test procedure in paragraph 4-22.
8.
NO AUDIO
Step 1. Check that the AUDIO LEVEL control set to midposition.
Step 2. Monitor A2TP7 (fig. 2- 1) with the oscilloscope. Audio will be present.
a. If correct go to step 4.
b. If not correct go to step 3.
Step 3. Turn the POWER switch to OFF. Check for a short to ground at XA2-1.
Step 4. Monitor terminal 1 of AUDIO LEVEL control R10 with the oscilloscope. Audio will be present.
a. If correct go to step 5.
Step 5. Monitor terminal 2 of AUDIO LEVEL control R10 and rotate the AUDIO LEVEL control from MIN to MAX. The audio will
vary from zero to a maximum.
a. If correct go to step 6.
b. If not correct replace AUDIO LEVEL control R10. This procedure requires direct support maintenance personnel
(refer to chapter 5).
Step 6. Monitor TB-8 of audio amplifier assembly A1. Audio will be present.
a. If correct go to step 7.
b. If not correct check the wiring between terminal 2 of AUDIO LEVEL control R10 and TB1-8 of audio amplifier
assembly A1 (fig. FO-3).
Step 7. Measure the dc voltage across the terminals of loudspeaker LS1.
a. If a dc voltage is present replace loudspeaker LS1. Replacing the loudspeaker requires direct support
maintenance personnel (refer to chapter 5).
9.
WRONG TIME DELAY
Step 1. Check the setting of TIME DELAY control A2R32 (fig. 2-1).
b. If not correct go to step 2.
Step 2. Set TIME DELAY control A2R32 to the delay desired. Go to table 4-2 and perform the maintenance turn on procedure.
10. SYSTEM DOES NOT ALARM (VISUAL AND AURAL)
Step 1. Press the ALARM TEST switch. The CARRIER LEVEL meter reading will go to less than -10 dB.
a. If correct go to step 2.
b. If not correct go to step 3.
Step 2. Check the voltage at A2TP3 (fig. 2-1). The voltage will be +24 Vdc.
a. If correct replace relay K1. This procedure requires direct support maintenance personnel (refer to chapter 5).
Step 3. Set POWER switch to OFF. Measure the resistance to ground from A3TP1 (fig. 2-1) when the ALARM TEST switch is
pressed. The resistance will be 0 ohm.
a. If correct replace if. amplifier assembly A2 (para 4-16).
b. If not correct check ALARM TEST switch S3 and the associated wiring (fig. FO-3).
11. NO AURAL ALARM
Step 1. Check that ALARM switch A1S1 fig. 2-1) is in the ON position.
a. If correct go to step 2.
b. If not correct set to the correct position and perform the maintenance turn on procedure in table 4-2.
Step 2. Measure the dc voltage across the terminals of loudspeaker LS1.
a. If a dc voltage is present replace loudspeaker LS1. This procedure requires direct support maintenance
personnel (refer to chapter 5).
b. If not correct go to step 3.
Step 3. Check for 0 Vdc at A2TP6 (fig. 2-1).
a. If correct replace audio amplifier assembly A1 (para 4-15) after checking the wiring between A2-12 and A1-7 (fig.
4-5
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