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  TM 11-6625-2946-14/TM 08168A-14/1
Table 5-1. Fault Isolation Chart--Continued
Symptom
Probable cause
Corrective action
a. Perform alignment procedure steps 19
a. Misaligned metering circuit.
No, or incorrect, XMT mode test indications.
through 22 (or 19a through 22a), table 5-2.
b. Faulty attenuator/power meter assembly.
meter detector dc output (A1E14) for a level
of 3. 0 vdc. If not present, remove El from
A6. Measure meter detection dc output. If
not present, replace assembly. If present,
reconnect El, measure voltage at A1E14. If
not present, replace board.
c. Replace board.
No, or incorrect, XMT mode test indications,
c. Faulty meter function board.
d. Check and replace or repair.
d. Defective FUNCTION switch or inter-
connection wiring,
a. Check and repair.
No, or low, FSM mode test indication.
a. Broken or loose ANTENNA connection.
b. Check and replace.
b. Faulty meter function board.
C. Check and replace or repair.
c. Defective FUNCTION switch or intercon-
nection wiring.
Section iii. MAINTENANCE
plug-in components are not considered necessary and are
5-5. General
therefore not included in this manual.
This section contains alignment instructions for the test
set. Due to the simplicity of the test set structure and in-
5-6. Alignment
terconnecting circuitry, detailed instructions for the
Alignment instructions for the test set are contained in
removal and replacement of test set circuit cards and
Table 5-2. Test Set Alignment Procedure
Step
no.
Procedure
1
Remove test set front panel from case (para 3-6).
With power supply PP-3940( )/G COARSE ADJ control fully counterclockwise, connect cable between O-36 VDC output connector of
2
power supply and 24 VDC EXT input connector on test set.
3
Place power supply ON/OFF switch in ON position and test set POWER switch in EXT position.
INPUT POWER VOLTA GE REGULATOR AND METERING CIRCUIT ADJUSTMENT
4
Adjust power supply COARSE ADJ and FINE ADJ controls for a reading of 24 vdc 0.5 Amps on its voltmeter.
Using Digital Voltmeter AN/USMA151, measure dc voltage across the test set RADIO input connectors and adjust 1A1A1R24 on meter
5
function board for a reading of 14 vdc.
Adjust power supply COARSE ADJ and FINE ADJ controls for a reading of + 12 vdc on its voltmeter.
6
7
Disconnect power supply from 24 VDC EXT connectors and connect it to the BATTERY connectors.
Place POWER switch in BAT position, Place and hold test set FUNCTION switch in BAT position and adjust 1A1A1R22 on meter func-
8
tion board for a reading of 5 divisions (midscale) on test set meter. Release FUNCTION switch.
9
Set test set FREQUENCY CODE switches to 3001 (54.05 MHz).
10
Adjust signal generator for a 2.8 µV output at 54.05 MHz and tune receiver for maximum deflection. Adjust receiver gain for a con-
venient reference level and note.
11
Disconnect signal generator and connect receiver to test set ANTENNA connector as shown in figure 5-3, connection B.
12
Depress test set SENS switch and observe test set meter level indication. If level indication is not equal to that noted in step 10 above,
perform steps 13, 15, and 16 below,
WARNING
Remove power before attempting to disassemble test set from its case.
13
Remove test set from case by loosening ten captive screws and lifting out.
Locate lAIAIR13 (figure 5-1 ) and adjust for an indication of 10 on the test set meter,
14
15
Loosen two set screws on the test set attenuator and move attenuator to produce a level on test set meter equal to the reference level
noted in step 10.
16
Secure set screws and repeat steps 9 through 12.
RECEIVER SENSITIVITY MEASURING CIRCUIT ADJUSTMENT
17
Place test set FUNCTION switch in RCV position.
18
Adjust 1A1A1R13 on test meter function board for a reading of 10 divisions (full-scale) on a test set meter.
5-4
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