Service manual

21HT-15C
21HT-16C
37
NO PICTURE, NO SOUND
CIRCUITS TO BE CHECKED:
Tuner.
PIF. Does the noise level increase at max.
Automatic Gain Control. Contrast,Brightness and Sound controls?
5V, 32V Power Source.
Noise increase but no No snow noise.
signal is received.
Check the tuner supply voltage Does noise or signal appear
LB and HB must be approx. 5V, at pin40 of IC801?
BT must be approx. 32V,and
NO YES
CH preset data check.
Does noise or Check IC801
signal appear at and its related
Normal pin38 of IC801? circuit.
NO YES
Check the tuner Does noise or
AGC at TP201. signal appear at Check Q401
pin23 and 24 Q402 and related
Normal Abnormal of IC801? circuit.
NO YES
Check pin38 Check pin27 Check pin1,2 of
of IC801. of IC801,Tuner SF201,Tuner Check pin37 of
and related circuit. and related IC801 and
circuit. related circuit.
NO SOUND
CIRCUITS TO BE CHECKED: NO
Audio Output Circuit. Does signal appear Check IC3001 and
at pin6 of IC302/303? its related circuit.
YES NO
Check Speaker. Check IC302/303 and
peripheral circuit.