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LWC3063ST/00 LG Microwave appears to function normally, but is not heating

Cu29head

Premium Member
Joined
Jul 19, 2021
Messages
4
Location
Raleigh, NC
Model Number
LWC3063ST/00
Brand
LG
Age
1-5 years
Hello all. I'm having an issue with the microwave in my wall oven combo. The microwave appears to function normally, but is not heating. I can hear the relays on the board working and i have checked the blower, magnetron, transformer and line filter. Any ideas? I do hear a loud pop when I first try to run it, but cant figure out where it's coming from. The pop only happens the first time I try to run it after a long cool down. I have also checked the safety switches after the pop and they are all closed. I'm frankly at a loss. Any thoughts? Thanks!
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
44,249
Location
Murray, Utah 84107, United States
When you start the microwave, check for 120 VAC on the primary side of the transformer. If the voltage is correct, the problem is one of the HV components.

C-HV Testing big.jpg
 
Last edited by a moderator:

Cu29head

Premium Member
Joined
Jul 19, 2021
Messages
4
Location
Raleigh, NC
Thanks for the reply. I tested all of the components per your diagram. Everything checked out except for the diode. My diode tested open in both directions. I went ahead and replaced it, as well as the capacitor. Now the unit has a very loud hum when attempting to heat. I've tested the magnetron per your instructions and tested for continuity to ground. Could the magnetron be bad and still give correct readings? Thanks again!
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
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Messages
44,249
Location
Murray, Utah 84107, United States
Now the unit has a very loud hum .....
A loud hum is usually associated with a bad diode or capacitor. Take the mag tube out and check the antenna for any burn marks. I think the mag tube can be bad and still test good. If one of the magnets is cracked it might make a loud hum.
 

Cu29head

Premium Member
Joined
Jul 19, 2021
Messages
4
Location
Raleigh, NC
Good call! Removed the magnetron and it had small burns on the antenna and some discoloration on the gasket. Otherwise, it tested fine. Created vibration that resonated throughout the microwave and oven when running
 

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Cu29head

Premium Member
Joined
Jul 19, 2021
Messages
4
Location
Raleigh, NC
Well, got the new magnetron and installed. No heating and loud hum and vibration is still present. The only part left in the HV section that hasn't been replaced is the transformer. Starting to doubt my meter.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
44,249
Location
Murray, Utah 84107, United States
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