No audio heard (1)
No sound in the UHF/VHF reception.
No external audio heard
Is the IF output from the tuner (TU1100) as specified?
Check TU1100 and its peripheral circuits.
NO
YES
Is the SIF signal input at pins (23) and (24) of IC1104 (IF PLL) as
specified?
Check Q1101, Q1104, SF1101 and their peripheral
circuits.
NO
YES
Is the audio signal from pin (12) of IC1104 to pin (67) of IC2501
(MULTI STANDARD SOUND PROCESSOR) as specified?
Check IC1104, IC2501 and their peripheral circuits.
(Q2500)
NO
YES
YES
YES
Is there the L-ch audio signal output at pin (28) of IC2501?
Is there the R-ch audio signal output at pin (27) of IC2501?
Check IC2501 and its peripheral circuits.
*A: Back from "No audio heard (3)"
NO
YES
<INPUT 1>
Is there the L-ch audio signal input from pin (5) of input terminal J1201 to pin
(56) of IC2501?
Is there the R-ch audio signal input from pin (3) of input terminal J1201 to pin
(57) of IC2501?
<INPUT 2>
Is there the L-ch audio signal input from pin (5) of input terminal J1202 to pin
(53) of IC2501?
Is there the R-ch audio signal input from pin (3) of input terminal J1202 to pin
(54) of IC2501?
<INPUT 3>
Is there the L-ch audio signal input from pin (5) of input terminal J1203 to pin
(50) of IC2501?
Is there the R-ch audio signal input from pin (2) of input terminal J1203 to pin
(51) of IC2501?
Is there the L-ch audio signal output at pin (7) of IC2504 (AMP)?
Is there the R-ch audio signal output at pin (1) of IC2504 (AMP)?
Check IC2504 and its peripheral circuits.
NO
NO
YES
Is there the L-ch audio signal input at pin (11) of IC2701 (Audio Output IC)?
Is there the R-ch audio signal input at pin (15) of IC2701 (Audio Output IC)?
Check IC2701, mute circuit and their peripheral
circuits. (Q2700 thru Q2702)
YES
Is there the L-ch audio signal output between pins (31) and (28) of IC2701 (Audio Output IC)?
Is there the R-ch audio signal output between pins (27) and (24) of IC2701 (Audio Output IC)?
NO
Check IC2701 and the audio mute logic circuit.
(Q2705, Q2706, D2501 thru D2503, D2700,
D2706)
YES
Check the relay circuit (RY2700) and its peripheral circuits.
Check the speakers and their peripheral circuits.
YES
No audio heard (2)
No audio signal at the monitor audio output terminal.
No sound heard from the headphone.
Is there the L-ch audio signal output at pin (34) of IC2501?
Is there the R-ch audio signal output at pin (33) of IC2501?
Check IC2501 and its peripheral circuits.
NO
YES
Is the L-ch audio signal outputted to Q1215?
Is the R-ch audio signal outputted to Q1216?
Check Q1215, Q1216 and their peripheral circuits.
NO
YES
NO
Does the audio mute circuit function? (Q1206 and Q1207)
Check Q1206, Q1207, Q1219, Q1220, pin (72) of
IC1203 and their peripheral circuits.
YES
Check the monitor audio output terminal (J1203) and its peripheral
circuits.
Is there the audio signal output at pins (25) (L-ch) and (24) (R-ch) of IC2501?
NO
YES
Is the mute signal input at pin (2) of IC2506 as
specified?
NO
Check Q3905, Q2705, Q2706 (MUTE CIRCUIT) and
their peripheral circuits.
Check J2500 and it peripheral circuits, as well as the headphone jack line.
Is there the L-ch audio signal output at pin (1) of IC2506 (H/P AMP)?
Is there the R-ch audio signal output at pin (7) of IC2506 (H/P AMP)?
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