21
LC-20S4E
TROUBLE SHOOTING TABLE
No
No
No
Yes
Yes
Yes
Yes
Yes
No
No
Yes
No
Yes
Yes
No
No
Yes
No
Yes
No
Yes
No picture and No sound
Back light lamp failure to light up
Replace F7701.
Is the voltage of
the base of Q7702
"L" state?
Check all output
voltage line for
short-circuit.
Do fuse F7701
function?
Is the voltage of
C7720, C7721,
C7722, C7723,
C7718 and C7725
of the secondary
output of T7701
normal?
Check Q6700-
Q6716 and their
periphery for short-
circuit.
Is there a short-
circuit in INV +B
line?
Check the OFL1
line, OFL2 line,
IC1201 and their
peripheral parts.
Check the OFL line,
Q3600, Q3601 and
their peripheral
parts.
Check Q6700-
Q6716 and their
peripheral parts.
Replace the back
light lamp with new
one and check
again.
Do fuse F6700-
F6704 function?
Are the pins (40)
and (138) of IC1201
"H" state?
Are the outputs of
Q3600 and Q3601
"L" state?
Is the pins (4) and
(7) of T6700-T6704
normal?
Is the pin (10) of
T6700-T6704
normal?
Check the error
amp circuit D6702-
D6711, Q6706,
Q6713, Q6717 and
their peripheral
parts.
Remove F7701 and
check the load side.
Is there a short-
circuit?
Is there a short-
circuit around the
primary side of
T7701?
Check IC7702,
IC7704 and their
peripheral parts.
Check IC7701 and
its peripheral parts.
Is T7701 primary
switching waveform at
pin (1) of IC7701
normal?
Summary of Contents for Aquos LC-20S4E
Page 29: ...31 6 5 4 3 2 1 A B C D E F G H LC 20S4E SCHEMATIC DIAGRAM Ë INVERTER Unit ...
Page 30: ...33 32 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë SUB Unit 1 2 ...
Page 31: ...35 34 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë SUB Unit 2 2 ...
Page 32: ...37 36 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë MAIN Unit 1 4 ...
Page 33: ...39 38 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë MAIN Unit 2 4 ...
Page 34: ...41 40 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë MAIN Unit 3 4 ...
Page 35: ...43 42 LC 20S4E 12 11 10 9 8 7 6 5 4 3 2 1 A B C D E F G H Ë MAIN Unit 4 4 ...
Page 36: ...44 6 5 4 3 2 1 A B C D E F G H LC 20S4E Ë OPERATION Unit ...
Page 37: ...45 6 5 4 3 2 1 A B C D E F G H LC 20S4E Ë R C LED Unit ...
