Tuner/If Circuit - Zenith XBR411 Manual

VCR ELECTRICAL TROUBLESHOOTING GUIDE

6. 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 Pin32.
YES
Does the Video signal
appear at IC601 Pin 4.
YES
Check the signal flow from IC601
Pin23 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.
NO
Check the signal flow from
IC501 Pin26.
NO
Check the signal from IC301 Pin26 to IC601 Pin4
3-15
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.