Tuner/If Circuit - LG DVS7905 Service Manual

6. Tuner/IF CIRCUIT

(A) No Picture on the TV screen
No picture on the TV
screen
YES
Does the Video signal at
the TU701 Pin24.
YES
Does Sync appear at
IC501 Pin111.
YES
Does the Video signal at
the IC501 Pin19.
YES
Does the Video signal at
the IC301 Pin61.
YES
Does the Video signal at
the IC802 Pin30.
YES
Check the signal flow from IC802
Pin30 to SC901 Pin19.
NO
Is 33VT applied to TU701
Pin16?
Is 5VT applied to TU701
Pin13?
Does the Clock signal
appear at TU701 Pin11?
Does the data signal
appear at TU701 Pin12?
Replace Tuner.
NO
Check the signal flow from
TU701 Pin24 to IC301 Pin48.
NO
Check the signal from IC301
Pin65 to IC501 Pin17.
NO
Check the signal from IC501
Pin19 to IC301 Pin56.
NO
Check the signal from IC501
Pin61 to IC802 Pin1.
3-18
NO
YES
NO
YES
NO
YES
NO
YES
Check 33VT line.
Check 5VT line.
Check the lIC Clock Signal
of µ-COM Pin59.
Check the lIC Data Signal
of µ-COM Pin60.