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3. Y/C CIRCUIT
(2) When the Y(Luminance) signal doesn't appear on the screen in PB Mode,
Is 5.0VT, 5.3VA applied to the
IC301 Pins24, 42, 55, 72, 91?
YES
Is the I
2
C Bus siganl applied
to the IC301 Pins68, 69 ?
YES
Does the normal RF signal
appear at the IC301 Pin78?
YES
Does the Y(Luminance) RF
signal appear at the IC301
Pin79?
YES
Is the Y(Luminance) Video
waveform showed up at
theIC301 Pin43?
YES
Replace the IC301.
NO
Check the line of the 5.0VT,
5.3VA Line. (Power Circuit)
NO
Refer to 'SYSTEM I
CHECK Trouble Shooting'.
NO
Is the V.H.S/W signal
applied to the IC301 Pin70?
Is V.H.S/W "H" about 3.4V
at the IC301 Pin70?
Clean the Drum.
Check the path of the
NO
Y(Luminance) RF signal.
(Check the C312)
Check the path of the
NO
Y(Luminance) RF signal.
(Check C327)
3-12
2
C BUS
NO
YES
NO
YES
NO
YES
YES
Check the System Circuit.
(IC501 Pin105)
Check the V.H.S/W level.
(Check R303, R304)
Replace the IC301.
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