LG LSC27931SB Service Manual page 67

Problems Problems Symptom Symptom
Bad defrost. Bad defrost. Defrost is not Defrost is not Defrost lead wire is cut. Defrost lead wire is cut.
working. working.
Defective defrost driving relay. Defective defrost driving relay.
Defective defrost sensor parts. Defective defrost sensor parts.
Defective Defective Buzzer Buzzer Defective connecting lead wire from Defective connecting lead wire from
buzzer buzzer continuously continuously main PCB to door switch. main PCB to door switch.
rings or door rings or door Defective door switch parts. Defective door switch parts.
opening alarm opening alarm
does not work. does not work.
Defective Defective Buzzer does Buzzer does Key input wire is cut or bad connector Key input wire is cut or bad connector
display button display button not sound not sound terminal contact in main PCB and terminal contact in main PCB and
and buttons and buttons display PCB connecting lead wire. display PCB connecting lead wire.
do not do not
operate. operate.
Key is continuously depressed due to Key is continuously depressed due to
structural interference. structural interference.
Causes Causes
Check if defrost lead wire is cut with a Check if defrost lead wire is cut with a
tester. tester.
Check the voltage of CON2 (1 and 7) Check the voltage of CON2 (1 and 7)
with a tester after pressing main with a tester after pressing main
PCB test switch twice. PCB test switch twice.
If the voltage is normal then it is OK. If the voltage is normal then it is OK.
Check the resistance of defrost sensor Check the resistance of defrost sensor
with a tester. with a tester.
Check lead wire related to door Check lead wire related to door
switch with a tester. switch with a tester.
Refer to door switch in parts repair Refer to door switch in parts repair
guide. guide.
Check input wire with a tester. Check input wire with a tester.
Disassemble frame display and confirm Disassemble frame display and confirm
visually. visually.
Checks Checks Measures Measures
Reconnect Lead Reconnect Lead
Wire. Wire.
Replace relay (RY 7 Refer to load Replace relay (RY 7 Refer to load
and RY 3) or PCB. and RY 3) or PCB.
Replace defrost Replace defrost
sensor. sensor.
Repair lead wire. Repair lead wire.
Replace door switch. Replace door switch.
Reconnect lead Reconnect lead
wire and replace or wire and replace or
directly connect bad directly connect bad
contact terminal to contact terminal to
lead wire. lead wire.
Adjust or replace Adjust or replace
interfering interfering
structures. structures.
Remarks Remarks
driving conditions driving conditions
check in circuit check in circuit
explanation. explanation.
Refer to sensor Refer to sensor
resistance resistance
characteristic characteristic
table of circuit table of circuit
explanation. explanation.
Refer to display Refer to display
circuit in circuit circuit in circuit
explanation. explanation.