3. Y/C CIRCUIT (2) When the Y(Luminance) signal doesn�t appear on the screen in PB Mode,
Is 5V applied to the IC301 Pins23, 44, 45, 52, 68, 77? YES Is the Y/C Bus siganl applied to the IC301 Pins53, 54, 55? YES Does the normal RF signal NO appear at the IC301 Pin 14? Is the V.H.S/W signal NO applied to the IC301 Pin57? YES Does the Rectangular waveform(5V) appear at the IC301 Pin57(V.H.S/W) YES NO Check the V.H.S/W level. Check the System Circuit. (IC501 Pin18) NO Refer to �SYSTEM Y/C BUS CHECK Trouble Shooting�. NO Check the line of the REG 5V Line. (Power Circuit)
YES
Clean the Drum.
Does the Y(Luminance) signal appear at the IC301 Pin20? YES
NO
Check the R328, C322, C323.
Is the Y(Luminance) Video NO waveform showed up at the IC301 Pin22? YES Replace the IC301.
