LG EC970W - Y(Luminance) signal not on screen in PB Mode

3-14
3. Y/C CIRCUIT
(2) When the Y(Luminance) signal doesn’t appear on the screen in PB Mode,
Is 5.2VT, 5.4VA applied to the
IC301 Pins 24, 42, 55, 72, 91?
Is the I
2
C Bus siganl applied
to the IC301 Pins 68, 69 ?
Does the normal RF signal
appear at the IC301 Pin 78?
Check the line of the 5.2V
Line. (Power Circuit)
Check the System Circuit.
(IC501 Pin 18)
Check the V.H.S/W level.
(Check R303, R304)
Replace the IC301.
Refer to ‘SYSTEM I
2
C BUS
CHECK Trouble Shooting’.
Is the V.H.S/W signal
applied to the IC301 Pin 70?
Is V.H.S/W “H” about 3.4V
at the IC301 Pin 70?
Clean the Drum.
Check the path of the
Y(Luminance) RF signal.
(Check C327)
Check the path of the
Y(Luminance) RF signal.
(Check the C312)
Does the Y(Luminance) RF
signal appear at the IC301
Pin 76?
Is the Y(Luminance) Video
waveform showed up at
theIC301 Pin 43?
Replace the IC301.
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO