Realistic trc-448 Service Manual page 26

Symptom Possible Cause
4) Does not receive SSB
RX AM : OK
TX AM SSB : OK
A) Defective Q215, Q216 and/or associated circuit
components
B) Defective Q217 and/or associated circuit components
5) Does not receive or transmit SSB
RX AM : OK
TX AM : OK
A) Defective Q1 and/or associated circuit components
6) Does not receive AM/SSB or transmit SSB
TX AM : OK
A) Defective XF201, Q207, Q208, T207, T208 and/or
associated circuit components
7) Does not receive both AM and SSB
A) Defective Q223, Q224, Q235 and/or associated circuit
components
8) No sound
TX AM SSB : OK
A) Defective speaker or defective EXT. SPKR jack
B) Faulty Squelch control circuit
C) Defective Relay
9) Does not transmit AM and SSB
A) Defective Q201, Q202, Q203, Q204, Q205 and/or
associated circuit components
B) Defective Relay, D251 and/or Microphone PTT switch
C) Defective MODE Switch
10)
Does not transmit AM
TX SSB : OK
A) Defective Q236, D228, MODE switch and/or associated
circuit components
11) Does not transmit SSB
TX AM : OK
RX AM SSB : OK
A) Defective IC-3, Q15, Q17, Q18 and/or associated circuit
components
B) Defective D19, D20, D21, D22, T9, D211 and/or
associated circuit components
C) Defective D249, D250 and/or associated circuit
components
12)
SQUELCH Control does not function
A) Defective VR-209 and/or VR-303
B) Defective VR-206
C) Defective Q230, Q231 and/or associated circuit
components
13) Receiver oscillates on AM
RX SSB : OK
A) Defective D1
B) Defective MODE switch
14) Low sensitivity
TX SSB : OK
A) Faulty AGC circuit Q219, Q220, Q221 and/or associated
circuit components
B) Defective Q228 and/or associated circuit components
C) Defective Q223, Q224, Q225 and/or associated circuit
components
15) No modulation on AM
TX SSB : OK
RX AM : OK
A) Defective IC-3, Q15, Q17, Q18 and/or associated circuit
components
B) Defective T216
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