LG FLATRON L1750S - Troubleshooting Common Issues

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TROUBLESHOOTING GUIDE
1. NO POWER
CHECK U801.
CHECK
U801 PIN 1& U803
PIN 3 VOLTAGE
(5V) ?
NO
NO POWER
(POWER INDICATOR OFF)
CHECK POWER BOARD,
AND FIND OUT A SHORT
POINT AS OPENING
EACH POWER LINE
CHECK J705 VOLTAGE
PIN5, PIN6 (5V)?
NO
CHECK 5VR LINE
(OPEN CHECK)
CHECK
Q803 PIN 3(3.3V) &
U803 PIN 4 (1.8V)?
NO
CHECK IIC LINE CONNECTION
(U501, U502)
CHECK U201 VCC, XTAL, RESET
IS U201
PIN88
VOLTAGE REPEATED
AS PULSE
SHAPE ?
NO
YES
YES
YES
NO PROBLEM
YES
CHECK KEY CONTROL
CONNECTOR ROUTINE
1
1
2
1 2
Waveforms
J705-#5, 6 / U801-#1/U803-#3 U201-#88
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