Zenith XBV243 Service Manual page 27

TROUBLESHOOTING (CONTINUED)
7. Tuner/IF CIRCUIT
(A) No Picture on the TV screen
No picture on the TV
screen
YES
Is the Video signal at
the TU701 Pin 24.
YES
Does Sync appear at
IC501 Pin 87.
YES
Does the Video signal at
IC501 Pin 45.
YES
Does the Video signal at
IC802 Pin 30.
YES
Check the signal flow from IC802
Pin 30 to JK801 Pin Video out.
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ELECTRICAL
Is +33V applied to TU701
Is +5V applied to TU701
Does the Clock signal
appear at TU701 Pin 11?
Does the data signal
appear at TU701 Pin 12?
Replace Tuner.
Check the signal flow from
TU701 Pin24 to IC301 Pin 31.
Check the signal from IC301
Pin52 to IC501 Pin 43.
Check the signal from IC501
Pin45 to IC802 Pin 1.
3-15
Pin16?
YES
Pin13?
YES
YES
YES
Check 33V line.
Check 5V line.
Check the lIC .Clock Signal
of µ-COM Pin90
Check the lIC Data Signal
of µ-COM Pin91.
D35E COMBO - ELECTRICAL