Sharp LC-37SD1E, Service Manual

Page: 42 / 182

LC-37SA1E/RU
4 – 2
No sound (1) (during the reception of TV broadcasting)
No audio output during UHF/VHF reception
Checklist;
1) Is the volume set to MIN or MUTE on the remote control?
•••
Set the desired volume.
2) Are headphones connected to HEADPHONE (J1301)?
•••
Disconnect them.
3) Is ANT-CABLE disconnected or connected improperly?
•••
Connect it correctly as per the operation manual.
Is the audio signal (L/R)
sent from pins (28) and
(27) of IC3002 (VCT)?
NO
Is the SIF signal ()
sent to pin (31) of IC3002
(VCT)?
YES
Check w5V and
+8V are supplied to pins
(33) and (18) of IC3002
respectively. Or, check
peripheral circuits.
(AV-UNIT) YES NO
Is the audio signal of pins
(3) and (5) of IC303
(OP-AMP) sent properly? NO Check SC2704 and P1201
or peripheral circuits.
Is the S-MUTE signal “L”? Is the audio signal (SIF)
sent from pin (1) of
CONNECTOR (SC2705)? YES Check pin (31) of IC3002
(VCT) and peripheral
circuits.
YES (TUNER) NO
Is the audio signal of pin
(4) of IC301/IC302
(AUDIO-AMP) sent
properly? NO Check HEAD-PHONE
(J1301) or peripheral
circuits. Is the audio signal (SIF)
sent from pin (12) of IC201
(IF-DEMOD)? YES Check connector (P201/
SC2705) and peripheral
circuits.
YES NO
Is the audio signal output
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal? NO Check P301 (AUDIO-
CONNECTOR) and
peripheral circuits. Is the SIF signal sent to
pins (23) and (24) of IC201
(IF-DEMOD)? YES Check IC201 and
peripheral circuits.
YES NO
Check Speaker (right and
left) and wire harness. Is the IF signal sent from
pin (8) of TUNER
(TU201)? YES Check FL202 and
peripheral circuits.
NO
Check whether 5V (CONT)
and 5V are supplied to
pins (1) and (7) of TUNER
(TU201) respectively.
Check SDA/SCL and AGC
signal. YES Replace TUNER (TU201).