Sharp LC-20B2EA Service Manual ▷ View online
13
LC-20B2EA
TROUBLE SHOOTING TABLE
No picture and No sound
Check all the settings microprocessor's adjust process menu.
Do F1 and F2 function?
Are T3701's secondary
outputs, +31V, +22V, +9V,
+5V and -8V normal?
Remove F1 and F2 and
check the load side.
Is there short-circuiting?
Is there short-circuiting of
T3701 primary side periphery,
Q3700, Q3701 and S4701.
Replace F1 and F2.
Check S4701 and
connection cable.
Is T3701's primary oscillator
waveform normal?
Check T3701's secondary
load.
Yes
Yes
No
No
No
No
No
Yes
Check J3702 periahery and
connection cable.
Replace F6700~F6704.
Is the pin (34) of IC1201 in
the "H" state?
Is the output of Q3650 in the
"L
" state?
Yes
Yes
No
No
No
Yes
Yes
Check the OFL1 line, IC1201
and their peripheral parts.
Check the OFL line, Q3650
and their peripheral parts.
Check T6700~T6709,
Q6700~Q6714 and
connection cable.
Back light lamp failure to light up
Is the primary side of
T6700 ~T6709 periphery
short-circuiting?
Replace the back light lamp
with new one and check
again.
14
LC-20B2EA
TROUBLE SHOOTING TABLE
(Continued)
No picture (1/3)
Check all the settings microprocessor's adjust process menu.
Is in/output of
IC801 normal?
Is in/output of
IC1201 normal?
Check IC801
and its
peripheral parts.
Check IC1201
and its
peripheral parts.
Check IC402
and its
peripheral parts.
Check IC801,
AV1 line and its
peripheral parts.
Check LCD
panel voltages
and waveform.
Yes
Yes
No
No
No picture
at all
Is in/output of
IC402 normal?
Is input at pin
(73) of IC801
normal?
Yes
No
No
No TV and
S-Video
output
Is voltages at
pins (6), (7) and
(18) of tuner
normal?
Is output at pin
(13) of tuner
normal?
Check their
power line.
Check tuner
and its
peripheral parts.
Is input at pin
(3) of tuner
normal?
Is the pins (2)
and (4) of IC402
at "H" and "L"
state?
Yes
Yes
No
No
No
No
No
Yes
No TV output
Is the pins (65)
and (66) of
IC2001 at "H"
and "L" state?
Yes
Check the its
line.
Check the its
line.
Check IC402
and its
peripheral parts.
Is input at pin
(75) of IC801
normal?
Check V1 IN
line and its
peripheral parts.
No
No
No VIDEO 2
output
Check the SY-line,
SC-line and their
peripheral parts.
Is input at pin (1)
of IC402 and pin
(71) of IC801
normal?
No S-VIDEO
output
15
LC-20B2EA
TROUBLE SHOOTING TABLE
(Continued)
No picture (2/3)
Check all the settings microprocessor's adjust process menu.
Is input at pin
(74) of IC801
normal?
Check the AV2
line and its
peripheral parts.
No VIDEO 1
output
Check IC1203
and its
peripheral parts.
No
No
No
Yes
Yes
Yes
No TELETEXT
output
Yes
Is input at pins (2),
(5), (11), and (14)
of IC1203 normal?
Is input at pins (3),
(4) and (5) of
SC1602 normal?
Is output at pins (1)
and (7) of IC1619 and
pin (1) of IC1620
normal?
No
Check connection
cable
Check the R, G
and B line.
No
Check IC1619,
IC1620 and their
peripheral parts.
Is output at pins
(57)~(59) of IC1601
normal?
No
Yes
Check V2VO line
and its peripheral
parts.
Is input at pin (21) of
IC1601 normal?
Check IC1601 and its
peripheral parts.
Is output of
R0~R7
normal?
Is output of
G0~G7
normal?
Is output of
B0~B7
normal?
Yes
Yes
No
No
No
Colour is
unusual
Check R1202 and
its peripheral parts.
Check R1203 and
its peripheral parts.
Check R1204 and
its peripheral parts.
Is in/output of
SPIO and
SPOI normal?
No
No picture
image
inversion
Gradation
defect
Is output of U/D
normal?
No
No
Check R1209 and
its peripheral parts.
Check IC1206,
IC1207, Q1201 and
their peripheral parts.
Is output V0, V7, V17,
V21, V32, V64, V122,
V176, V235 and
V255 normal?
Check IC1106,
IC1107, IC1108,
IC1114, IC1115 and
their peripheral parts.
16
LC-20B2EA
TROUBLE SHOOTING TABLE
(Continued)
No sound (1/2)
Check all the settins microprocessor's adjust process menu.
Is the pin (53) of
IC2001 in the
"L" state?
Is output at pins
(27) and (28) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC1903 normal?
Yes
Yes
No
No
No
No sound
from front
speakers
Yes
Muting effect is
on. Check the
FSMUTE line.
Check IC1901
and its
peripheral parts.
Check IC1903
and its
peripheral parts.
Is the pin (52) of
IC2001 in the
"L" state?
Is output at pins
(24) and (25) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC304 normal?
Yes
Yes
No
No
No
Yes
Muting effect is
on. Check the
HP_MUTE line.
Check IC1901
and its
peripheral parts.
Check IC304
and its
peripheral parts.
No sound
from
headphone
TV sound
failure
Is output at pins
(33) and (34) of
IC1901 normal?
Is output at pins
(1) and (7) of
IC3500 normal?
Check IC1901
and its
peripheral parts.
Check IC3500
and its
peripheral parts.
Yes
No
No
No
No sound
from output
line
Check the tuner
and its
peripheral parts.
Yes
No
Is output at pin
(11) of Tuner
normal?
Is input at pins
(67) and (69)
of IC1901.
Check IC1901
and its
peripheral
parts.
Check
Headphone Jack
and connection
cable.
No
Is output at pins
(8) and (12) of
IC3305 normal?
Check IC3305
and its
peripheral parts.
Check front
speaker and
connection
cable.
Yes
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