LG LMV1762SB, Service Manual

-12-

A.  SINCE NEARLY 4,000 VOLTS EXISTS IN SOME 

CIRCUITS OF THIS UNIT REPAIRS SHOULD BE 

CARRIED OUT WITH GREAT CARE. 

The filament leads of the magnetron carry High 

Voltage with respect to the ground. Extreme 

caution must be exercised. Never plug the unit 

into a power source to determine which 

component is defective in the high voltage section.

B.  TO AVOID POSSIBLE EXPOSURE TO 

MICROWAVE ENERGY LEAKAGE, THE 

FOLLOWING PRECAUTIONS MUST BE TAKEN 

BEFORE SERVICING.

(1) Before the power is applied:

(a)   Make sure the primary interlock switch, the 

secondary interlock switch and the interlock 

monitor switch operate properly by opening 

and closing the door several times.

(b)   Make sure the perforated screen and the 

dielectric choke of the door are correctly and 

firmly mounted.

(2) After power is applied:

(a)   Make sure the interlock switch mechanism 

is operating properly by opening and closing 

the door.

(b)   Check microwave energy leakage must be 

below the limit of 5 mW/cm2 . 

(All service adjustments should be made for 

minimum microwave energy leakage 

readings).

(3)   Do not operate the unit until it is completely 

repaired. If any of the following conditions exist, 

the unit must not be operated.

(a)  The door does not close firmly.

(b)  The hinge is broken.

(c)  The door seal is damaged.

(d)   The door is bent or warped, or there is any 

other visible damage on the unit that may 

cause microwave energy leakage.

NOTE: Always keep the seal clean.

(e)   Make sure that there are no defective parts 

in the interlock mechanism.

(f)    Make sure that there are no detective parts 

in the microwave generating and transmission 

assembly (especially waveguide).

(4)   The following items should be checked after the 

unit is repaired:

(a)   The interlock monitor switch is connected 

correctly and firmly.

(b)   The magnetron gasket is properly positioned 

and mounted.

(c)   The waveguide and the oven cavity are 

intact. (no microwave energy leakage)

(d)   The door can be properly closed and the 

safety switches work properly.

(e)   The unit must stop when the door is opened 

or the time is up.

The unit must not be operated with any of the above

components removed or bypassed.

1. Press “Defrost weight/time” for 2 seconds , unit will 

display “TEST” and Beep once;

2. The unit will check if the PCB humidity sensor and 

PCB thermistor are short or open.

3. If it has an error, it will beep and display an error 

code.

4. If the unit is normal , it will beep and display 

"PASS".

5.Press “ Clear” to return to Standby mode. 

6-2. Safety Caution

6-3  Self diagnosis (humidity Sensor and PCB thermistor check) & 

Error code

Error code
F-1
F-2
F-4

Symptom
PCB thermistor short
PCB thermistor open
Humidity sensor open or short