Sharp 13VT-L200 Service Manual page 54

Circuit to be checked:
NO PICTURE, NO SOUND
1. TUNER
2. PIF
3. Automatic gain control
4. 9V power source
Does the noise level increase at max,
Contrast, Brightness, and Sound Control?
Noise increases but
no signal is received
NO
Is there a signal at pin Is there a signal at
(41) of IC401? pin (37) of IC401?
YES YES
Check the IC401 and adjacent parts
NO
Is there a signal at pin Check the Q404,
(43) of IC401?
Q433 and adjacent
parts.
YES
Check the IC401 and
adjacent parts.
Check the tuner bias.
Abnormal
Normal
Check IC2001.
Check the tuner AGC.
Normal Abnormal
Check the
Check IC401.
Tuner circuit.
FLOW CHART NO.2-3
Picture noise
decrease but sound
level varies greatly.
NO YES Is there a signal at NO
pin (53) of IC401.
Is there
Check
a signal
Is there
the
at pin
a signal
NO
IC401
(8) of at pin
and
IC351 (54) of
adjacent
(TDA
IC401?
parts.
7233)?
YES YES
Check
Is there
the
a signal Check
NO
IC401,
at pin the
and
(5) of IC351.
adjacent
IC351?
parts.
YES
Check
the
speaker.
Does the 9V (+B)
appear at pin (48)
of IC401?
Normal Abnormal
Check the
Check IC401.
PC9V line.
NO VERTICAL SCAN
Vertical freq check
Normal
Pin (22) of IC401 bias
check.
Normal
NO
IC501 (LA7830) bias
check.
Normal
Check the CRT
connector K1~K6 and
adjacent parts.
FLOW CHART NO.2-4
Abnormal
CF631 (503kHz)
Abnormal
IC401
Abnormal
D502, C509, C510 and
R511