Toshiba SD-33VB, Service Manual

Page: 61 / 197

3-12
3. Y/C CIRCUIT
(2) When the Y(Luminance) signal doesn’t appear on the screen in PB Mode,
Is 5.2VT, 5.3VA applied to the
IC301 Pins24, 42, 55, 72, 91?
Is the I 2 C Bus siganl applied
to the IC301 Pins68, 69 ?
Does the normal RF signal
appear at the IC301 Pin78?
Check the line of the 5.2VT,
5.3VA Line. (Power Circuit)
Check the System Circuit.
(IC501 Pin105)
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 Pin70?
Is V.H.S/W “H” about 3.4V
at the IC301 Pin70?
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
Pin76?
Is the Y(Luminance) Video
waveform showed up at
theIC301 Pin43?
Replace the IC301.
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES