Aiwa HV-FX7800 Service Manual page 48

ELECTRICAL TROUBLESHOOTING -8/17
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
Pins 16, 40, 55, 58, 87?
Is the I 2 C Bus siganl applied
to the IC301 Pins 23, 24?
Does the normal RF signal
appear at the IC301 Pin 74?
Does the Y(Luminance) RF
signal appear at the IC301
Pin 17?
Is the Y(Luminance) Video
waveform showed up at
theIC301 Pin 41?
Replace the IC301.
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
Check the line of the 5.2V
Line. (Power Circuit)
Refer to 'SYSTEM I 2 C BUS
CHECK Trouble Shooting'.
Is the V.H.S/W signal applied
to the IC301 Pin 11 ?
YES
Is V.H.S/W "H" about 3.4V
at the IC301 Pin 11?
YES
Clean the Drum.
Check the path of the
Y(Luminance) RF signal.
(Check the Q301)
Check the path of the
Y(Luminance) RF signal.
(Check Q302, Q303)
-48-
NO
Check the System Circuit.
(IC501 Pin 105)
NO
Check the V.H.S/W level.
(Check R304, R340)
NO
Replace the IC301.
YES
YES