Sharp LC-20B5E (serv.man8) Service Manual ▷ View online
23
LC-20B5E
TROUBLE SHOOTING TABLE
No picture and No sound
Check all the settings microprocessor's adjust process menu.
Do F3701 and F3702
function?
Are T701's secondary
outputs, +35V, +9V, +5V, -7V
and -12V normal?
Replace F3701 and F3702.
Check S4053 and
connection cable.
Is T701's primary oscillator
waveform normal?
Check T701's secondary
load.
Yes
Yes
No
No
No
No
No
Yes
Check J3701 periphery and
connection cable.
Replace F6700~F6704.
Yes
Yes
No
No
No
Yes
Yes
Check the OFL line, Q3701,
Q3702 and their peripheral
parts.
Check T6700~T6704,
Q6700~Q6705, Q6707~
Q6712, Q6714~Q6716 and
connection cable.
Back light lamp failure to light up
Is the primary side of
T6700 ~T6704 periphery
short-circuiting?
Replace the back light lamp
with new one and check
again.
Remove F3701 and F3702
and check the load side.
Is there short-circuiting?
Is there short-circuiting of
T701 primary side periphery,
Q709, Q711, Q716 and S4053.
Are the pins (10) and (11) of
IC1201 in the "H" state?
Are the outputs of Q3701 and
Q3702 in the
"L
" state?
Check the OFL1 line, OFL2
line, IC1201 and their
peripheral parts.
24
LC-20B5E
TROUBLE SHOOTING TABLE
(Continued)
No picture (1/3)
Check all the settings microprocessor's adjust process menu.
Is in/output of
IC8801 and
IC8501 normal?
Is in/output of
IC1201 normal?
Check IC8801,
IC8501 and their
peripheral parts.
Check IC1201
and its
peripheral parts.
Check LCD
panel voltages
and waveform.
Yes
Yes
No
No
No picture
at all
Is voltages at
pins (7), (9) and
(15) of tuner
normal?
Is output at pin
(13) of tuner
normal?
Check the
power line.
Check tuner
and its
peripheral parts.
Is input at pin
(47) of IC3401
normal?
Is output at pin
(40) of IC3401
normal?
Yes
Yes
No
No
No
No
No
Yes
No TV output
Is output at pin
(73) of IC8801
normal?
Yes
Check the its
line.
Check the its
line.
Check IC3401
and its
peripheral parts.
Is input at pin
(8) of IC3401
normal?
Check V2_V
line and its
peripheral parts.
No
No VIDEO 2
output
25
LC-20B5E
TROUBLE SHOOTING TABLE
(Continued)
No picture (2/3)
Check all the settings microprocessor's adjust process menu.
Is input at pin
(2) of IC2201
normal?
Check IC2201
and its peripheral
parts.
No VIDEO 1
output
Check the V2_SY-line,
V2_SC-line and their
peripheral parts.
Is input at pin (10) ,
(12) of IC3401
normal?
No S-VIDEO
output
Check IC8801
and its
peripheral parts.
No
No
No
No PC Card
output
Yes
Yes
Yes
No TELETEXT
output
Is input at pins (1),
(2), (3), and (79) of
IC8801 normal?
No
Check the R, G, B
and FB line.
Is input at pins (6)~(8)
and (14) of IC1602
normal?
No
No
Yes
No
Yes
No
No
Yes
Check their lines
and its peripheral
parts.
Is output at pins
(57)~(59) and (60) of
IC1601 normal?
Check IC1601 and its
peripheral parts.
Are the card medium
and its files normal?
Is the voltage at pins
(24), (27), (74) and
(77) of SC5401 at the
PC card part normal?
Is the voltage at pin
(3) of IC5409 and
pins (1), (2) and (3)
of IC5004 normal?
Check the medium
and its files.
Check the power
supply line.
Check the power
supply line.
Is output at IC8602
and IC8606 normal?
Check that line.
26
LC-20B5E
TROUBLE SHOOTING TABLE
(Continued)
No picture (3/3)
Check all the settings microprocessor's adjust process menu.
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
Is in/output of
SPIO and
SPOI normal?
No
No picture
image
inversion
No
Gradation
defect
Is output of UD
normal?
Yes
No
Check R1265 and its
peripheral parts.
Check R1261 and
its peripheral parts.
Check IC1201, R1224
and its peripheral
parts.
Check R1266 and its
peripheral parts.
Check R1267 and its
peripheral parts.
Is output V0, V7, V21,
V64, V112, V176,
V235 and V255
normal?
Check IC1101 and its
peripheral parts.
Display