Sharp 15JF-25S Service Manual page 31

15JF-25S
CIRCUITS TO BE CHECKED:
Tuner.
PIF.
Automatic Gain Control.
5V, 32V Power Source.
LB and HB must be approx. 5V,
Check pin38
of IC801.
CIRCUITS TO BE CHECKED:
Audio Output Circuit.
NO PICTURE, NO SOUND
Does the noise level increase at max.
Contrast,Brightness and Sound controls?
Noise increase but no
signal is received.
Check the tuner supply voltage
BT must be approx. 32V,and
CH preset data check.
Normal
Check the tuner
AGC at TP201.
Normal Abnormal
Check pin27
of IC801,Tuner
and related circuit.
Check Speaker.
No snow noise.
Does noise or signal appear
at pin40 of IC801?
NO
Does noise or
signal appear at
pin38 of IC801?
NO
Does noise or
signal appear at
pin23 and 24
of IC801?
NO
Check pin1,2 of
SF201,Tuner
and related
circuit.
NO SOUND
NO
Does signal appear
at pin6 of IC303?
YES NO
Check IC303 and
peripheral circuit.
36
YES
Check IC801
and its related
circuit.
YES
Check Q401
Q402 and related
circuit.
YES
Check pin37 of
IC801 and
related circuit.
Check IC801 and
its related circuit.