LG FLATRON 568LM LM568E-CA, Service Manual

Page: 13 / 39

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TROUBLESHOOTING GUIDE
1. NO POWER
CHECK U4.
CHECK
U4 PIN 8 VOLTAGE
(5V) ?
NO
NO POWER
(POWER INDICATOR OFF)
CHECK ADAPTER,
AND FIND OUT
A SHORT POINT
AS OPENING
EACH POWER LINE
CHECK J1’S
VOLTAGE
(12V) ?
NO
CHECK L11
(OPEN CHECK)
CHECK
U5 Voltage
(5V) ?
NO
U13’S PIN11
0V ?
CHECK U13, AND
CHECK 5VA LINE
CHECK IIC LINE
CONNECTION
(U4, U1)
CHECK U3’S VCC,
XTAL, RESET
IS U13 PIN2
VOLTAGE REPEATED
AS PULSE SHAPE ?
NO
YES
YES
YES
NO
YES
NO PROBLEM
NO
CHECK KEY CONTROL
CONNECTOR ROUTINE