Zenith XBV613 - DVD/VCR Combination Service Manual page 22

3. Y/C CIRCUIT
(2) When the Y(Luminance) signal doesn't appear on the screen in PB Mode,
Is 5V applied to IC301
Pins23, 44, 45, 52, 68, 77?
YES
Is the Y/C Bus siganl
applied to IC301 Pins53,
54, 55?
YES
Does the normal RF signal
appear at IC301 Pin14?
YES
Does the Y(Luminance)
signal appear at IC301
Pin20?
YES
Is the Y(Luminance) Video
waveform shown at IC301
Pin22?
YES
Replace IC301.
NO
Check the line of the SW
5V Line.
Refer to 'SYSTEM Y/C
NO
BUS CHECK Trouble
Shooting'.
NO
Is the V.H.S/W signal
applied to IC301 Pin57?
Does the Rectangular
waveform(5V) appear at
IC301 Pin57(V.H.S/W)
Clean the Drum.
NO
Check R328, C322, C323.
NO
Check C324.
3-11
NO
YES
NO
YES
Check the System Circuit.
(IC501 Pin18)
Check the V.H.S/W level.