LG TL-AT130M - Manual (Page 16)

3-6
SECTION3 ELECTRICAL
ELECTRICAL TROUBLESHOOTING GUIDE
3. Y/C CIRCUIT
(1) No Video in EE Mode
Does the Video signal appear
at the IC301 Pin29?
NO
NO
NO
Check the IC3G1 Pin14
and Q3G1 emitter.
Check the path of the signal between
the IC301 Pin29 and IC501 Pin49.
Is there 9V on the plus
terminal of the C381?
No Video in EE Mode
Does the Video signal appear at the
IC3G1 Pin9?
YES
Does the Video signal appear
at the IC301 Pin38?
YES
Check the Video input Jack &
jack Board connection.
YES
Is I 2 C BUS signal applied to the
IC301 Pin 23, 24?
Check C316.(AGC)
Replace the Q380.
Check the System Circuit. (Refer to
‘SYSTEM I 2 C BUS Trouble Shooting’)
NO
Does the Video signal appear
at the IC501 Pin 47?
YES
Does the Video signal appear at
the Emitter terminal of the Q380?
YES
NO
NO
NO
YES
Replace the IC301.
YES
Check the 9V Line.
(Power Circuit)
NO
Is 5V applied to the
IC301 Pin16, 40, 55, 58, 75, 87?
YES
Check the 5VA Line.
(Power Circuit)
NO