Table 4-2 Maintenance Turn-On Procedure

TM 11-5825-270-23

Table 4-2 Maintenance Turn-On Procedure-Continued

Step

Procedure

Observation

Corrective Action

During the keying sequence turn

After the delay set by TIME DE-

If the delay is wrong refer to

SENSITIVITY control A3R7 (fig. 2-1)

LAY control A2R32 the NORM

table 4-3, malfunction 9.

counterclockwise to reduce the

indicator will be off, the ALARM

If the receiver does not alarm

CARRIER LEVEL meter reading

indicator will be on, the aural

refer to table 4-3, malfunction 10.

to the setting of CARRIER control

alarm will sound, and the remote

If there is no aural alarm refer

A2R22 (fig. 2-1) plus 1 dB.

alarm will be on.

to table 4-3, malfunction 11.

If there is no remote alarm refer

to table 4-3, malfunction 6.

If the NORM and ALARM in-

dicators are both off refer to

table 4-3, malfunction 4.

During the keying sequence turn

a. CARRIER LEVEL meter will

Refer to table 4-3, malfunction 13.

SENSITIVITY control A3R7

read 0 dB 1 dB.

clockwise until the receiver reverts

b. NORM indicator will be on and

b. If both indicators are off refer

back to normal operation.

ALARM indicator will be off.

to table 4-3, malfunction 4. If

NORM indicator is off and

ALARM indicator is on refer to

table 4-3, malfunction 13.

c. Aural alarm will be off.

c. Refer to table 4-3, malfunction 11.

d. Remote alarm will be off

d. Refer to table 4-3, malfunction 6.

Adjust SENSITIVITY control

None.

A3R7 for a CARRIER LEVEL

meter reading of 0 dB.

Table 4-3. Monitor Receiver Troubleshooting

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

INDICATING FUSE LIGHTED

Step 1. Replace the fuse.

a. If the indicating fuse is off go to table 4-2 and complete the maintenance turn on procedure.

b. If indicating fuse is on go to step 2.

Step 2. Disconnect the ac input at J2. Visually inspect the wiring at TB1 of the power supply, at transformer T3 and at fuse F1.

Replace the fuse and go to step 3.

Step 3. Disconnect the leads at TB1 of the power supply. Use the multimeter to check for de isolation from ground for the leads

from TB1-1, TB-3, TB-4, TB1-5, and TB-6.

a. If there is dc isolation go to step 4.

b. If there is no dc isolation for the leads from TB1-1 and TB1-3 check the wiring associated with TB 1-1 and TB 1-3

(fig. FO-3). Disconnect the if. amplifier PCB, rf PCB and audio amplifier PCB from their connectors to isolate the

short to either the wiring harness or a PCB (fig. FO-3).

c. If there is no dc isolation for the lead from TB-4 replace capacitor C2.

d. If there is no dc isolation for the leads from TB1-5 and TB1-6 replace transformer T3. This procedure requires

direct support maintenance personnel (refer to chapter 5).

Step 4. Check for a short between TB1-2 and TB1-5 and between TB1-2 and TB1-6 of the power supply.

a. If there is no short go to step 5.

b. If there is a short replace power supply assembly A4 para 4-17).

Step 5. Check for dc isolation from ground for terminals 1, 2, 3, and 4 of transformer T3.

a. If there is dc isolation go to step 6.

b. If there is no dc isolation replace transformer T3. This procedure requires direct support maintenance personnel

(refer to chapter 5).

Step 6. Check the resistance of the primary windings of transformer T3; between terminals 1 and 2 and between terminals 3 and

4. The resistance will be about 25 ohms.

a. If resistance is correct go to step 7.

b. If resistance is zero replace transformer T3. This procedure requires direct support maintenance personnel (refer

to chapter 5).

Step 7. Check for dc isolation between primary and secondary windings of transformer T3 (between terminals 1 and 5).

a. If there is isolation go to step 8.

b. If there is no dc isolation replace transformer T3. This procedure requires direct support maintenance personnel

(refer to chapter 5).

4-3