TM 11-5826-225-35
d. Receiver Troubleshooting Chart.
Procedure
Indication
Probable trouble
Remove power and check transistor Q14 (fig.
Defective audio output stage
No audio output but con-
1
t r o l unit tuning meter
Make voltage measurements on audio output
indicates signal
stage (fig. 217 ).
strength.
Make continuity tests on audio output trans-
former T20 (para 2-9a).
Remove power and check transistors Q12 and
First or second audio ampli-
Q13 (fig. 2-4).
fier stage defective.
Make voltage measurements on first and sec-
ond audio amplifier stages (fig. 2-17).
Using vtvm, check voltage output from cath-
Audio detector defective ----
ode of audio detector CR1 (fig. 2-14 or 2-14.1)
Check continuity of Z1.
Network Z1 defective _____
Check transistor Qll (fig. 2-8),
Fifth IF amplifier defec-
tive.
Make voltage measurements (fig. 2-17).
Check transistor Q21 (fig. 2-3).
Bfo defective ---. -.. __..._
W i t h control unit BFO-
2
OFF switch to BFO, no
Make voltage measurements (fig. 2-17 ).
beat notes can be heard
in headset connected to
PHONE jack on test
set.
A u d i o output is normal
3
Meter rectifier defective ___
Using vtvm, check dc output voltage of di-
ode CR1O (fig. 2-14 or 2-14.1) ,
but control unit tuning
meter is inoperative.
No audio output or tuning
4
Regulated power supply de-
See item 9
meter indication.
fective.
F i r s t , second, third, or
Check transistors Q7, Q8, Q9, and Q1O (fig.
fourth IF amplifier stage
Make voltage measurements (fig. 2-17).
defective.
Make continuity checks on IF transformers
T14, T15, T16, and T17 (para 2-9a).
Perform signal substitution tests (para 2-6).
Make stage gain measurements (para 2-7).
Check mixer Q5 (fig. 2-8).
Mixer stage _______________
Make voltage measurements (fig. 2-17).
Check continuity of T13 (para 2-9a).
Check oscillator Q6 (fig, 2-8).
Local oscillator stage defec-
5
Audio output missing on
Make voltage measurements (fig. 2-17).
tive.
one or more frequent:
ranges,
Make continuity checks on oscillator coils
Clean switch contacts (fig. 2-8).
S w i t c h wafer S1-J dirty---
Align oscillator (para 3-13).
Oscillator out of alignment .
U s i n g transistor tester, check agc ampli-
Automatic gain control cir-
6
Signal output varies
fiers Q15 and Q16 (fig. 2-3).
cuit defective.
Using vtvm, check dc output voltage of agc
7
First IF amplifier Q7
rectifier CR3 (fig. 2-14 or 2-14.1)
Make voltage measurements on agc ampli-
fiers Q15 and Q16 (fig. 2-3).
Check transistors Q2 and Q4 (fig. 2-8).
Sense antenna input circuit
Weak audio output on on
R
or more frequency
or push-pull RF amplifier.
ranges.
Make voltage measurements (fig. 2-17).
Change 1 2-19
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