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Page Title:
Table 3-5. Circuit Card Troubleshooting. (cont) |
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 TM 11-5895-1097-40
Table 3-5. Circuit Card Troubleshooting.
Malfunction
Probable cause
Corrective action
3. NO GO indicator always lights to show status
a.
Rcvr circuit out of alinement
a.
Set up equipment as shown in figure 3-5. Set signal
of rcvr xtal module
(1) First mixer stage module local
generator RF output to 100 uV at 18.1 MHz.
oscillator alinement
(1) Connect RF volmeter to TPI I and adjust TI and
C32 for maximum voltage.
(a) T1 and C32 peak. Continue troubleshooting.
b. Abnormal indication go to step b below.
(2) First mixer stage xtal module
(2) Remove signal input from J5 and connect to J6
RF amplifier alinement
(RF plug). Adjust R22 for minimum signal.
(a) R22 dips. Continue troubleshooting.
(b) Abnormal indication go to step b below.
(3) Comparator U6A alinement
(3) Reconnect signal input to J5. Using multimeter,
check for + 1.4 Vdc at TP12. Adjust R45.
(a) If correct, check for 1.5 Vdc at TP13. Adjust R44.
(b) If incorrect at TP12, check power supply U2.
(c) If incorrect at TP13, go to step b below.
(4) Comparator U6C alinement
(4) Set RF output to 50 mV at 132.7 MHz. Using
multimeter, check for 1.9 Vdc at TP14. Adjust R46.
(a) If correct, check for 2 Vdc at TP15. Adjust R26.
(b) If incorrect at TP14, check power supply U2.
(c) If incorrect at TP15, go to step b below.
b.
Defective first mixer stage
b. Set up equipment as shown in figure 3-5. Using RF
voltmeter check for at least 275 mV at TP8.
(1) If correct, continue troubleshooting.
(2) If incorrect, check A2 components and wiring,
and FLI.
c. Defective second local oscillator
c. Using RF voltmeter, check for at least 75 mV at TP9.
stage
(1) If correct, continue troubleshooting.
(2) If incorrect, check Q6, YI, and associated
components.
d.
Defective second mixer stage
d. Using RF voltmeter, check for at least 40 mV at
TP10.
(1) If correct, continue troubleshooting.
(2) If incorrect, check pi network, Q5, FL2 and
associated components.
e.
Defective if. amplifier stage
e. Using RF voltmeter, check for at least 2 Vrms at
TP11.
(1) If correct, continue troubleshooting.
(2) If incorrect, check Q7, Q8, Q9 and associated
components.
f.
Defective overtone detector
f.
Using RF voltmeter, check for at least 4 Vrms at
TP7.
(1) If correct, continue troubleshooting.
(2) If incorrect, check CR5, CR6 and associated
components.
g.
Defective comparator U6A
g. Using multimeter, check for + 0.1 Vdc maximum at
TP18.
(1) If correct, continue troubleshooting.
(2) In incorrect, replace U6.
h.
Defective comparator U6C
h. Using multimeter, check for + 0.1 Vdc maximum at
TP19.
(1) If correct, continue troubleshooting.
(2) If incorrect, replace U6.
i.
Defective logic gate
i.
Using multimeter, check for at least 5 Vdc at E19
and E22.
(1) If correct, check R58, R60, R62, Q11 and
associated wiring.
(2) If incorrect, replace U7.
4.
Test set rcvr power jacks (+ 6, + 12, GND) do not Defective U2 regulator circuit
Using multimeter, check RI, R2, R3, R4, C3, C4.
power AN/GRA-114 RCVR circuit cards
a. If correct, replace U2.
b. If incorrect, replace defective component.
3-14
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