Y/C Circuit - LG V9120W Service Manual

4. Y/C CIRCUIT

(1) No Video in EE Mode,
No Video in EE Mode
Does the Video signal
appear at the IC301 Pin48?
YES
Is 5V applied to the IC301
Pins18, 24, 42, 55, 72, 91?
YES
Does the Video signal
appear at the IC301 Pin65?
YES
Does the Video signal
appear at the IC501 Pin47?
YES
Does the Video signal appear
at the Emitter terminal of the
Q309?
NO
Check the 19Pin of Tuner.
NO
Check the 5.0VT, 5.3VA
Line. (Power Circuit)
NO
Is I 2 C BUS signal applied to
the IC301 Pins68, 69?
YES
Chck the path of the signal
NO
between the IC301 Pin65
and IC501 Pin49.
Does the 12VT, 5.3VA
NO
appear at the Emitter
terminal of the Q309.
YES
Replace the Q309.
3-11
Check the System Circuit.
NO
(Refer to 'SYSTEM I
CHECK Trouble Shooting')
Check C316. (AGC)
NO
Replace the IC301.
Check the 12VT, 5.4VA
Line. (Power Circuit)
2 C BUS
YES