Y/C Circuit - LG RCT689H Service Manual

VCR ELECTRICAL TROUBLESHOOTING GUIDE

4. Y/C CIRCUIT

4-1. When the Y(Luminance) signal doesn't appear on the screen in PB Mode,
When the Y(Luminance)
signal doesn't appear on the
screen in PB Mode,
YES
Is 5.0V
5.3VA applied to
IC301 Pin18,24,42,
55,72,91?
YES
Is I 2 C
BUS signal applied to
the IC301 Pin68,
69?
YES
Does the normal RF signal
appear at IC301 Pin79?
NO
Check the line of the 5.0V
5.3V Line. (Power Circuit)
Refer to "SYSTEM I 2 C
NO
BUS CHECK Trouble
Shooting".
Is the
NO
V.H.S/W signal
applied to IC301
Pin70?
Is the
V.H.S/W "H" about
3.4V at the
IC301 Pin70?
Clean the Drum.
3-11
NO
YES
NO
YES
NO
Check the System Circuit.
(IC501 Pin23)
Check the V.H.S/W level.
(Check R323)
Check the IC301.