Troubleshooting Guide - LG LF-U850D Service Manual

SECTION 2. ELECTRICAL SECTION
❏ TROUBLESHOOTING GUIDE
P-SENS PART CHECK
SMPS ASSY CN943 -> 4PIN 5V OPERATION CHECK
NO
YES
MAIN PCB PN101 4PIN 5V CHECK
NO
YES
MAIN PCB PN304 27PIN 5V CHECK
YES
FRONT CN304 7PIN 5V CHECK
YES
FRONT IC302 OPERATION AND INPUT VOLTAGE 4.7V~5.0V CHECK
NO
YES
U-COM 26PIN 5V CHECK
VKK CHECK
CN943 6PIN DC -33V CHECK
NO
YES
MAIN PCB PN101 6PIN VOLTAGE -33V CHECK
NO
YES
PN304 3PIN VOLTAGE CHECK (-33V)
NO
YES
FRONT PCB CN304 3PIN VOLTAGE CHECK (-33V)
NO
YES
IC301 51PIN VOLTAGE CHECK
REFER TO SMPS TROUBLESHOOTING
PN101 CONTACT STATUS CHECK
YES
MAIN PCB PATTERN disconnection check
IC302 INPUT VOLTAGE 4.7V OR ABOVE , OUTPUT VOLTAGE
3V OR ABOVE OPERATION CHECK
YES
IC304 KIA7042 REPLACEMENT
REFER TO SMPS TROUBLESHOOTING
MAIN PCB PATTERN DISCONNECTION CHECK
FFC WIRE ASSEMBLY STATUS CHECK
FRONT PCB PATTERN DISCONNECTION CHECK
- 2-1 -