Sharp AN-S422U, Service Manual

Page: 42 / 166

42
XG-V10WU
AN-SD1U/S422U
TROUBLE SHOOTING TABLE
(Continued)
Checking the video unit circuit
Yes
No
Check the IC1403, IC1406 selector
switch, terminal voltage and input
circuit.
Yes
No
Is there video signal input at IC4001?
Check the low-pass and buffer
circuits of Q4002, Q4003 and Q4004.
Yes
No
Are there signal outputs at pins (6)
and (8) of IC4001?
Check IC4001 and its peripheral
circuits (bias).
Yes
No
Check the low-pass and buffer circuits
of Q6008 thru Q6014. Is the signal as
specified?
Go to "Checking IC801 (RGB signal
output circuit)".
Is there video signal output at pin (7)
of IC1405?
Check Q4005 thru Q4008 and their
peripheral circuits.
Checking IC801 (RGB signal output circuit)
Yes
No
Check the data transfer and other
performance at pins (17) and (18) of
video IC803.
No
Go to "No colour or unusual tone",
"No Y signal" or "Out of sync".
Yes
No
Are there output waveforms at pin
1
of Q6801, Q6802, Q6803?
Check Q6801, Q6802, Q6803 and
their peripheral circuits.
No
Are there output waveforms at pin
(8), (10), (12) of SC8404?
Check IC6801, Q6807, Q6808,
Q6809 and their peripheral circuits.
Yes
Are there RGB output waveforms at
pins (31), (32) and (33) of IC803?
Go to "Trouble shooting table for PC
I/F unit".