Tuner/If Circuit - Zenith XBV323 Series Service Manual

VCR ELECTRICAL TROUBLESHOOTING GUIDE

7. Tuner/IF CIRCUIT

(1) No Picture on the TV screen
No picture on the TV
screen
Does the Video signal
appear at TU701 Pin16.
YES
Does the video signal
appear at IC302 Pin7.
YES
Does the Video signal
appear at IC501 Pin 52.
YES
Does the Video signal
appear at IC602 Pin 7.
YES
Check the signal flow from IC602
Pin7 to JK601 Pin Video out.
NO
Is +33V applied to TU701
Pin14?
Is +5V applied to TU701
Pin3?
Does the Clock signal
appear at TU701 Pin9?
Does the data signal
appear at TU701 Pin10?
Replace Tuner.
Check the signal flow from
NO
IC501 Pin27.(Pin27 is 'L'
state in Tuner Mode)
NO
Check the signal from IC301
Pin26 to IC501 Pin50.
NO
Check the signal from IC501 Pin52 to IC602 Pin1 and IC602 Pin2.
(IC602 Pin2 is 'L' state in VHS mode)
3-18
NO
YES
NO
YES
NO
YES
NO
YES
Check 33V line.
Check 5V line.
Check the l 2 C Clock Signal
of µ-COM Pin71.
Check the l 2 C Data Signal
of µ-COM Pin72.