Troubleshooting Guide - LG LB500J Service Manual

TROUBLESHOOTING GUIDE

NO POWER
(POWER INDICATOR OFF)
CHECK J707
VOLTAGE
PIN1&PIN2(12V)
PIN4(5V)?
YES
CHECK
U501 PIN 8
VOLTAGE
(5V) ?
YES
CHECK
U805 Voltage
(5V) ?
YES
CHECK KEY CONTROL
CONNECTOR ROUTINE
IS U201 PIN12
VOLTAGE REPEATED
AS PULSE SHAPE ?
NO
CHECK IIC LINE
CONNECTION
(U501, U502)
1. NO POWER
NO
NO
NO
NO
CHECK U201 VCC,
XTAL, RESET
- 13 -
CHECK POWER
BOARD, AND FIND
OUT A SHORT POINT
AS OPENING
EACH POWER LINE
CHECK U803.
CHECK 5VS LINE
(OPEN CHECK)
NO PROBLEM