Zenith XBV 443, Service Manual

Page: 27 / 108

3-18
7. Tuner/IF CIRCUIT
(1) No Picture on the TV screen
No picture on the TV
screen
Does the Video signal at
the TU701 Pin16.
YES
YES YES
Is +33V applied to TU701
Pin14?
YES
Is +5V applied to TU701
Pin3?
NO
Does the Video signal at
the IC501 Pin 52.
NO
Does the Video signal at
the IC609 Pin 23.
YES
NO
Check the signal flow from IC609
Pin23 to JK901 Pin Video out.
YES
Check 33V line.
NO
Check 5V line.
NO
YES
Does the Clock signal
appear at TU701 Pin9? Check the lIC Clock Signal
of µ-COM Pin71.
NO
YES
Does the data signal
appear at TU701 Pin10?
Replace Tuner.
Check the signal from IC301
Pin29 to IC501 Pin50.
Check the signal from IC501
Pin52 to IC609 Pin4.
Check the lIC Data Signal
of µ-COM Pin72.
NO