LG Microwave: LMVM2033ST /01 does not heat anymore

[Sipho22]

Symptoms: The microwave runs just fine, but nothing warms up no matter how long you put it in for. 

Troubleshooting: The transformer seems to be fine.  The capacitor looks fine (to be fair, I didn't meter it, cause it is hard to reach) The magnetron has been replaced twice... It always seems to fix the problem, but after two or three weeks it stops working again.  I don't see any charring on or around the magnetron like it is overheating.  The large magnets don't appear to be cracked.  In fact, once I remove the apparently bad magnetron, I meter it out, and it looks fine... but I put a new one in and it works again for a short time.  It doesn't seem like a power issue, transformer, capacitor, diode... It seems like it's the magnetron, but I don't want to keep replacing it every month.  Any ideas?

[ServiceTech_Daniel]

When the microwave is running and not heating, do you hear the magnetron actually coming on? 

These LG's are equipped with a HV fuse that is in series with just the High Voltage side of the microwave (Not to be confused with the 20 amp fuse on the noise filter . The part number for the HV fuse is EAF36358316 check it like you would check any other fuse . 

That will halt all heating. 

Also check for 120 on the low voltage side of the transformer when your testing it . If your not getting 120 you might have a bad Mag Relay on the board .

Unfortunately i've had to replace 5 of those HV fuse's in the past 6 month's with no other underlining issue's ..maybe just a bad patch of fuses got into production

 

 

[Sipho22]

I replaced the fuze.  Since I had to dissect more of it to get there, I could reach the diode, so I replaced that too.  Kept the same magnetron.  It's all working now, and it looks like it was the diode as I tested each component that I took out.  Thanks for your help.

[ServiceTech_Daniel]

Glad to hear that you were able to fix it !