Localizing Troubles - TM-11-6625-667-450061

TM 11-6625-667-45/NAVSHPS 0969-249-8010/NAVAIR 16-30APM123-2/T0 33A1-3-367-22

on the sectionalization test step (para 3-4) that the

3-6. Localizing Troubles

failure was noted.

a. General. The troubleshooting charts (d

through e below) outline procedures for localiz-

Note. Test setup and condition should be as specified

ing troubles to a stage within the respective mod-

at the step in the sectionalization test where the trouble

was noted.

ule or subassembly. Figures 8-6 through 8-16 are

schematic diagram Figures 8-25 through 8-37

c. Power Supply Section Troubleshooting. Re-

are parts location diagrams. To check stages or

fer to figure 8-6 for schematic diagram and to

parts in either transmitter A16 or the 28-volt

figures 3-8 and 3-9 for socket voltage and

power supply, refer to paragraph 3-10 for instruc-

resistance

tions to remove the subassembly.

Caution: If replaced fuses blow, turn off

b. Use of Troubleshooting Charts. A trouble-

power and refer to paragraph 3-5 to locate

shooting chart is provided for each module or sub-

short circuit

assembly. Selection of the applicable chart is based

Probable trouble

Corrective measures

Symptom

a. Check A15CR1 through A15CR4 (fig

+28 volts abnormal----------- a. Bridge rectifier-------- - - - - - - - - -

8-37).

b. Regulator diode --------------

b. C h e c k d i o d e A 1 5 V R 1 .

c. Check continuity and resistance across

c. Power transformer ---------------------

primry and secondary of A15T1.

d. Check continuity of A15L1.

d. Series inductor -------------------

Transistor A13Q1, A13Q2, or A13QJ3---

Check socket voltages and resistances (fig.

+12volts

abnormal-----------

3-8).

a. Check voltages and resistances (fig. 3-8).

12volts abnormal, +156 volts a. Transistor A3Q4-----------------

b. Resistor A13R8------------------

b. Check resistance against rated value.

normal.

c. Check diodes A14CR1 through A14CR4.

c. -l8-volt bridge rectifier-----------

If normal, check capacitor A14C7.

Transistor A14Q1, A14Q2, A14Q3,

12 volts abnormal and +156

Check socket voltages and resistance (fig.

volts abnormal.

or A14Q4.

3-9).

+150 volts abnormal, -12 volts a. Voltage adjustment-------------.

a. Adjust control A14R8 to obtain normal

voltage.

normal.

b. Transistor A14Q5, A14Q6, or

b. Check socket voltages and resistances

A14Q7.

(fig. 3-9).

c. Check A14CR6, through A14CR9 and

c. + 150-volt bridge rectifier -------- --

capacitors A14C8 and A14C9. Replace

defective part.

d. Transmitter A16 Troubleshooting. Socket voltages and resistances are shown in figure 3-10, and

the schematic diagram is figure 8-7.

Probable trouble

Corrective measures

Symptom

Incorrect frequency----------

A16Y1----------------------------- Replace crystal A16Y1.

a. Cable connections to PROBE jack. a. Tighten loose cable connection. Replace

No RF power output with test

point A4TP5 or A4TP4

broken cable or connector.

grounded.

b. Transistors and tubes:

b. Check transistors and tubes listed in

(1) A16Q1; A16Q2

Probable trouble column in the order

(2) A16Q3; A16V1, or A16A1V1.

given; use voltage and resistance

(3) A16A2Q1, A16A2Q2 or

diagram.

A16A2Q3.

No RF power with test point

Transistor Al6Ql-------------------- Check A16Q1; use socket voltage and resist-

A4TP5 grounded, but normal

ance diagram.

With A4TP4 grounded.

3-16