LG TL-AT130M - Manual (Page 22)

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SECTION3 ELECTRICAL
ELECTRICAL TROUBLESHOOTING GUIDE
(2) No F.OSD display.
(3) No Key display
Is there 5.3V IC501 Pin 51?
NO
NO
Replace bad switches
Replace X502.
No Key display
Is there 5.2VA at IC501
Pin79, 80, 81?
YES
As pressing the byttons doeseach
function work properly?
YES
Check power circuit
Check 5.3V Line of power
circuity.
Does oscillation appear at the
IC501 Pins 40, 41?
NO
NO
NO
YES
Does oscillation appear at the
IC501 PIns 37, 38?
YES
Check peripheral circuit and
replace X501
YES
No OSD display.
6. OSD CIRCUIT
(1) No OSD display.
Does Video signal appear at the
IC501 Pin 47?
YES
NO
Check the signal between
IC501 Pin47 and V.out Jack.
Replace IC501.
YES
Refer to “(5) No OSD picture”
Check the signal between IC301
Pin 29 and IC501 Pin 49.
YES
Check power Vcc 9V
Replace IC501
NO
NO
YES
Does video signal appear at
IC501 Pin 50?
YES
No F.OSD display.