Sharp LC-20C2E (serv.man4) Service Manual ▷ View online
14
LC-20C2E
TROUBLE SHOOTING TABLE
No picture, No sound
Check all the settings microprocessor's adjust process menu.
Do F2, F3, F4 and F5
function?
Are T701's secondary
outputs, +38V, +16V, +9V,
+5V and -8V normal?
Remove F2, F3, F4 and F5
and check the load side.
Is there short-circuiting?
Is there short-circuiting of
T701 primary side periphery,
Q751, Q753 and P901.
Replace F2, F3, F4 and F5.
Check P901 and
connection cable.
Is T701's primary oscillator
waveform normal?
Check T701's secondary
load.
Yes
Yes
No
No
No
No
Yes
Fluorecent lamp failure to light up
Does F1 function?
Is the pin 34 of IC1201 in
the "H" state?
Is the Q3603 short-circuiting?
Is there short-circuiting of
T5701 and T5702 primary
side periphery, Q751~Q753.
Yes
Yes
No
No
No
Yes
Replace the fluorecent lamp
with new one and check
again.
Yes
Check the OFL1 line, IC1201
and their peripheral parts.
Check Q3603 and their
peripheral parts.
Check T5701, T5702,
Q5701~Q5703 and
connection cable.
15
LC-20C2E
TROUBLE SHOOTING TABLE
(Continued)
No picture
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
VIDEO 1
output
Is voltages at
pin 3 of W7 and
pins 3, 4, 5 of
W14 tuner
normal?
Is output at pin
2 of W7 tuner
normal?
Check the
power line.
Check tuner
and its
peripheral parts.
Is input at pin
3 of IC402
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
1 of IC402
normal?
Is the pins 2
and 4 of IC402
at "L" state?
Check the its
line.
Check the its
line.
Check IC402
and its
peripheral parts.
Is the pins 65
and 66 of IC2001
at "L" state?
Yes
Yes
No
No
No
No VIDEO 1
output
16
LC-20C2E
TROUBLE SHOOTING TABLE
(Continued)
No picture
Check all the settings microprocessor's adjust process menu.
Is input at pin
74 of IC801
normal?
Check the AV2
line and their
peripheral parts.
Check the W9,
SY-line, SC-line
and their
peripheral parts.
No
No VIDEO 2
output
Is input at pins
71 and 72 of
IC801 normal?
No
No S-VIDEO
output
Is input at pin
70 of IC801
normal?
Check the
V2VO line and
their
peripheral parts.
No
No line
output
Is input at pins
1, 2, 3, 56, 57
and 79 of IC801
normal?
Is output at pins
11, 13 and 16
of I4 normal?
Check IC801
and their
peripheral parts.
Check I13 and
their
peripheral parts.
Check I9 and
their
peripheral parts.
Check I4 and
their
peripheral parts.
Is output at pins
11, 13 and 16
of I13 normal?
Yes
Yes
No
No
No
No TELETEX
output
Is output at pins
44~49 of I9
normal?
Yes
No
17
LC-20C2E
TROUBLE SHOOTING TABLE
(Continued)
No picture
Check all the settings microprocessor's adjust process menu.
Is source GND
normal?
Is CSCOM
waveform
normal?
Check R1212
and their
peripheral parts.
Check IC1109,
Q1101, Q1102,
D1101, R1120,
R1130 and their
peripheral parts.
Check R1231
and their
peripheral parts.
Yes
No
No
Becomes
dark
No
Time passes,
becomes
dark
Is gate GND
normal?
Is gate clock
(GCK) normal?
Check R1223
and gate aray
peripheral parts.
Yes
No
Check D1201
and their
peripheral parts.
No
Is B-5.5V being
outputted?
Is VCC being
outputted?
Check T701's
secondary +5V
outputs line?
Yes
No
Is GSP
waveform
normal?
Check R1223
and their
peripheral parts.
Yes
No
Becomes
white.
Is 3.3V VHS
being
outputted?
Is source clock
normal?
Check +3.3V
outputs line of
IC752.
Check R1210,
R1211 and their
peripheral parts.
Check FB1203
and gate aray
peripheral parts.
Is output of LBR
and HG
normal?
Yes
Yes
No
No
No
Vertical line
output
No picture
Check all the settings microprocessor's adjust process menu.
Is output of
R0~R5
normal?
Is output of
G0~G5
normal?
Is output of
B0~B5
normal?
Check R1202,
R1203 and their
peripheral parts.
Check R1204,
R1205 and their
peripheral parts.
Check R1206,
R1207 and their
peripheral parts.
Check T701's
secondary +5V
outputs line.
Yes
Yes
No
No
Colour is
unusual
Is VLS 5V
being
outputted?
No
Picture
image is
gloomy
Is in/output of
SPIO and
SPOI normal?
Check R1209
and their
peripheral parts.
No
No picture
image
inversion
Is output V0,
V16, V32, V48
and V63
normal?
Check IC1106,
IC1107, IC1108
and their
peripheral parts.
No
Gradation
defect
Is output of U/D
normal?
Check Q1201
and their
peripheral parts.
Yes
No
