Read Sharp LC-37GE1E (serv.man7) Service Manual online
LC-37GE1E
7 – 1
LC-37GE1E
Service Manual
CHAPTER 7.
TROUBLE SHOOTING TABLE
[1] TROUBLE SHOOTING TABLE
Power unit operation check.
Are the power cord and harness in the unit properly con-
nected ?
NO
Connect the power cord and harness properly, and turn on the power.
YES
Is F701 normal ?
NO
Are both ends of C704 and C715 short-circuited when checking their
resistance values?
YES
NO
YES
Is a voltage of BU5V applied to pin (20) of P701?
(Set the main power SW to OFF.)
(Set the main power SW to OFF.)
NO
Replace F701.
C704 ... Check VA701 ,
VA702 and D701.
C715 ... Check IC704
and 705.
VA702 and D701.
C715 ... Check IC704
and 705.
YES
Is it a symptom that the relay clatters twice as soon as the
main power SW is set to ON and the power is not supplied?
main power SW is set to ON and the power is not supplied?
Is a voltage of approx. 8 - 15V
to pin (4) of IC705?
to pin (4) of IC705?
NO
Check IC705, IC708,
D725 and Q724.
D725 and Q724.
NO
YES
YES
Does the same symptom
appear even if R858 (2.7k) is
removed and the power is sup-
plied again ?
appear even if R858 (2.7k) is
removed and the power is sup-
plied again ?
NO
Check short circuit of 5V line
(D737, C752, etc.).
(D737, C752, etc.).
YES
Check Q724, D731 , D734,
IC707, D751 , D753, D754,
D741 , D759 and D746.
IC707, D751 , D753, D754,
D741 , D759 and D746.
Check IC704, D728, D762 and D736. If there are no problems, check
the resistance value between pins (1) and (6) of P704.
When the value is low (several
the resistance value between pins (1) and (6) of P704.
When the value is low (several
Ω- several hundred Ω), disconnect
P704. If the value is still low, the parts of 24V line are defective. When
the resistance value is several
the resistance value is several
Ω, check the inverter unit.
Does a relay noise sound? (Once)
NO
Are PCON1 and 2 [pins (1)
and (2) of P702] at Hi (3V or
more)?
and (2) of P702] at Hi (3V or
more)?
NO
There is a possibility that
control by P-CON is not
performed
properly. Check whether
the "PCON1" and
"PCON2" signals
are sent from pins (A23)
and (A21) of IC3002 (V-
PRO.) of MAIN-UNIT.
control by P-CON is not
performed
properly. Check whether
the "PCON1" and
"PCON2" signals
are sent from pins (A23)
and (A21) of IC3002 (V-
PRO.) of MAIN-UNIT.
YES
YES
Check peripheral circuits of D738, R828 and D735.
Check peripheral circuits of
Q712, Q713, Q721, Q723
and RY701.
Q712, Q713, Q721, Q723
and RY701.
LC-37GE1E
7 – 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.
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 IC3701 (MSP)?
sent from pins (28) and
(27) of IC3701 (MSP)?
NO
Is the SIF signal
(ANA_IN1+) sent to pin
(67) of IC3701(MSP)?
(ANA_IN1+) sent to pin
(67) of IC3701(MSP)?
YES
Check whether +5V and
+8V are supplied to pins
(12) and (39) of IC3701
respectively. Or,check
peripheral circuits.
+8V are supplied to pins
(12) and (39) of IC3701
respectively. Or,check
peripheral circuits.
(AV-UNIT)
YES
NO
Is the audio signal of pins
(3) and (5) of IC303 (OP-
AMP) sent properly?
(3) and (5) of IC303 (OP-
AMP) sent properly?
NO
Check IC303 or
peripheral circuits.
peripheral circuits.
Is the audio signal (SIF)
sent from pin (1) of CON-
NECTOR (SC2705)?
sent from pin (1) of CON-
NECTOR (SC2705)?
YES
Check pin (67) of IC3701
(MSP) and peripheral cir-
cuits.
(MSP) and peripheral cir-
cuits.
YES
(TUNER)
NO
Is the audio signal of pin
(4) Of IC301/IC302
(AUDIO-AMP) sent prop-
erly?
(4) Of IC301/IC302
(AUDIO-AMP) sent prop-
erly?
NO
Check HEAD-
PHONE
(J1301) or periph-
eral circuits.
PHONE
(J1301) or periph-
eral circuits.
Is the audio signal (SIF)
sent from Q210 (Buffer)?
sent from Q210 (Buffer)?
YES
Check CONNEC-
TOR(P201) and periph-
eral circuits.
TOR(P201) and periph-
eral circuits.
YES
NO
Is the audio signal output
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ?
of pins (2) and (4) of P301
(AUDIO-CONNECTOR)
normal ?
NO
Check P301
(AUDIO- CON-
NECTOR) and
peripheral circuits.
(AUDIO- CON-
NECTOR) and
peripheral circuits.
Is the SIF signal sent to
Q203 (AMP)?
Q203 (AMP)?
YES
Confirm whether +8V is
supplied to Q203. Or,
please check the periph-
eral circuit.
supplied to Q203. Or,
please check the periph-
eral circuit.
YES
NO
Has the audio signal cor-
rectly come to SP sub-
strate (D790WE/
D791WE)?
rectly come to SP sub-
strate (D790WE/
D791WE)?
NO
Check the connec-
tion of P301 and
the SP substrate
and harnesswire.
tion of P301 and
the SP substrate
and harnesswire.
Is the SIF signal sent from
pin (13) of TUNER
(TU201)?
pin (13) of TUNER
(TU201)?
YES
Check soldering the ter-
minal
and peripheral circuits.
minal
and peripheral circuits.
YES
NO
Check SP-BOX (right and
left) and wire harness.
left) and wire harness.
Check whether 5V (ANT )
and 5V are supplied to
pins (4) and (10) of
TUNER (TU201) respec-
tively. Check SDA/SCL
and AGC signal.
and 5V are supplied to
pins (4) and (10) of
TUNER (TU201) respec-
tively. Check SDA/SCL
and AGC signal.
YES
Replace TUNER
(TU201).
(TU201).
LC-37GE1E
7 – 3
No sound from external input devices (2) -1
No sound from an external input
device connected to EXT1
(SCART1).
device connected to EXT1
(SCART1).
No sound from an external
input device connected to
EXT2 (SCART2).
input device connected to
EXT2 (SCART2).
No sound from an external input
device connected to EXT3.
device connected to EXT3.
<EXT1>
Is IN1-L audio signal sent from
pin (6) of SCART1 terminal
(J1101) to pin (53) of IC3701
(MSP)?
Is IN1-R audio signal sent from
pin (2) of SCART1 terminal
(J1101) to pin (54) of IC3701
(MSP)?
Is IN1-L audio signal sent from
pin (6) of SCART1 terminal
(J1101) to pin (53) of IC3701
(MSP)?
Is IN1-R audio signal sent from
pin (2) of SCART1 terminal
(J1101) to pin (54) of IC3701
(MSP)?
YES
<EXT2>
Is IN2-L audio signal sent
from pin (27) of SCART2 ter-
minal (J1101) to pin (56) of
IC3701 (MSP)?
Is IN2-R audio signal sent
from pin (23) of SCART2 ter-
minal (J1101) to pin (57) of
IC3701 (MSP)?
Is IN2-L audio signal sent
from pin (27) of SCART2 ter-
minal (J1101) to pin (56) of
IC3701 (MSP)?
Is IN2-R audio signal sent
from pin (23) of SCART2 ter-
minal (J1101) to pin (57) of
IC3701 (MSP)?
YES
<EXT3>
Is IN3-L audio signal sent from
pin (3) of
J1201 terminal to pin (47) of
IC3701?
Is IN3-R audio signal sent from
pin (5) of J1201 terminal to pin
(48) of IC3701?
Is IN3-L audio signal sent from
pin (3) of
J1201 terminal to pin (47) of
IC3701?
Is IN3-R audio signal sent from
pin (5) of J1201 terminal to pin
(48) of IC3701?
NO
NO
NO
Check pins (6) and (2) of
SCART1 and connection to an
external input device.
SCART1 and connection to an
external input device.
Check pins (27) and (23) of
SCART2 and connection to
an external input device.
SCART2 and connection to
an external input device.
Check pins 3 (J1201) and 5
(J1201) of EXT3 and connec-
tion to an external input device.
(J1201) of EXT3 and connec-
tion to an external input device.
Is the audio signal properly sent from pins (28) and (27) of IC3701 ?
NO
YES
Check IC3701 or peripheral circuits.
Is the audio signal of pins (1)
and (7) of IC303 (OP-AMP)
sent properly?
and (7) of IC303 (OP-AMP)
sent properly?
NO
Check IC303 or peripheral circuits.
YES
Is the audio output signal of
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
NO
Check IC302/IC301 (MAIN-AMP), HEAD-
PHONE and peripheral circuits.
PHONE and peripheral circuits.
YES
.
Check
CONNECTOR(P301),
SP_substrate(D790WJ/
D791WJ) and
SP-BOX(right and left).
D791WJ) and
SP-BOX(right and left).
LC-37GE1E
7 – 4
No sound from external input devices (2) -2
No sound from EXT4 (AUDIO)
connecting an external input
device.
connecting an external input
device.
No sound from EXT5
(AUDIO) connecting an exter-
nal input device.
(AUDIO) connecting an exter-
nal input device.
<EXT4>
Is D-SUB-L audio signal sent
from J2702 to pin (15) of
IC2704?
Is D-SUB-R audio signal sent
from J2702 to pin (2) of IC2704?
Is D-SUB-L audio signal sent
from J2702 to pin (15) of
IC2704?
Is D-SUB-R audio signal sent
from J2702 to pin (2) of IC2704?
<EXT5>
Is HDMI-L audio signal sent
from J2701 to pin (14) of
IC2704?
Is HDMI-R audio signal sent
from J2701 to pin (5) of
IC2704?
Is HDMI-L audio signal sent
from J2701 to pin (14) of
IC2704?
Is HDMI-R audio signal sent
from J2701 to pin (5) of
IC2704?
YES
YES
Is D-SUB-L audio signal sent to
pin (50) of IC3701?
Is D-SUB-R audio signal sent to
pin (51) of IC3701?
pin (50) of IC3701?
Is D-SUB-R audio signal sent to
pin (51) of IC3701?
Is HDMI-L audio signal sent
to pin (50) of IC3701?
Is HDMI-R audio signal sent
to pin (51) of IC3701?
to pin (50) of IC3701?
Is HDMI-R audio signal sent
to pin (51) of IC3701?
NO
Check output of pins (13) and (3) of IC2704
and peripheral circuits.
and peripheral circuits.
YES
OK
Is the audio signal properly
sent from pins (28) and (27)
of IC3701 ?
sent from pins (28) and (27)
of IC3701 ?
NO
Check IC3701 or peripheral circuits.
YES
Is the audio signal of pins (1)
and (7) of IC303 (OP-AMP)
sent properly?
and (7) of IC303 (OP-AMP)
sent properly?
NO
Check IC303 or peripheral circuits.
YES
Is the audio output signal of
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
pins (13) and (16) of IC302/
IC301(MAIN-AMP) normal?
NO
Check IC302/IC301 (MAIN-AMP), HEAD-
PHONE and peripheral circuits.
PHONE and peripheral circuits.
YES
.
Check
CONNECTOR(P301),
SP_substrate(D790WJ/
D791WJ) and
SP-BOX(right and left).
D791WJ) and
SP-BOX(right and left).