LG TL-AT130M Service Manual page 17

ELECTRICAL TROUBLESHOOTING GUIDE
(2) When the Y(Luminance)signal doesn't appear on the screen in PB Mode.
Is 5V applied to the IC301
Pin 16, 40, 55, 58, 87?
Is the I 2 C Bus signal applied
to the IC301 Pin 23, 24?
YES
Does the normal RF signal
appear at the IC301 Pin74?
YES
Does the Y(Luminance) RF signal
appear at the IC301 Pin 17?
YES
Is the Y(Luminance) Video waveform
showed up at the IC301 Pin 41?
YES
Replace the IC301.
SECTION3 ELECTRICAL
NO
Check the line of the 5.3VA
Line. (Power Circuit)
NO
Check the System Circuit. (Refer to
2
'SYSTEM I C BUS Trouble Shooting')
NO
Is the V.H.S/W "H" about
3.4V to the IC301 Pin11 ?
YES
Is V.H.S/W "H" about 3.4V at the
IC301 Pin 11?
YES
Clean the Drum.
NO
Check the path of the Y(Luminance)
RF signal.(Check the Q301)
NO
Check the path of the Y(Luminance)
RF signal.(Check Q302, Q303)
NO
Check the System Circuit.
(IC501 Pin 23)
NO
Check the V.H.S/W level.
(Check R304, R305)
NO
Replace the IC301.
YES
YES
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