My LG Microwave Oven model: MC-7880PSR became faulty after 2.5 yrs of use from purchase.
There were absolutely no fault symptoms appearing from outside except it was neither heating nor cooking. Chamber light coming ON at door open, turn table rotates like previous with glass of water on top and door light goes OFF when door closed. No unusual sound or smell. Also this situation emerged suddenly, no un-even power supply problem or anything else.
I ringed to LG customer care no. and booked the fault. A company representative approached me day after and attended the fault.
He told there are three common places where fault appears in this kind of gadgets.
(a) Door Switch (b) Capacitor and (c) Magnetron. Chamber light was operating with door. So no fault in Door Switch. He checked Capacitor by shorting it’s both terminals with a screw driver. Sparking shows it is OK. Now he come to conclusion that leftover thing is Magnetron and it might be faulty.
He replaced the Magnetron and switched ON the Oven with a glass of water inside. Now it is working well.
Magnetron in Oven comes with only 2 yrs of warranty and a new costing between 1200 – 1800 INR (as on date Feb 1016). General life span is 2 – 5 yrs and mostly fault appears in Magnetron.
Common fault reasons are:
 Use of non-microwave or metal utensils.
 Presence of moisture or insects (like Cockroach) in Circuit Board area.
 Power Supply fluctuations.
Shared by -- Mr. Sumit.