Friday, February 3, 2012

Technology - Engineering Applications - Dissasembling a Microwave Pt1

   So a few weeks ago I got an old microwave from one of my teachers, Joel Hammon. Its an old GE profile performance, over-the-range microwave/convection oven; it was made in the year 2000 according to the serial code. It had been sitting in Joel's shed for over 5 years, and he wanted to get rid of it. I didn't check to see if it still works, but I have been waiting forever to take a microwave apart. It had quite a lot of screws, and a lot of sheet-metal. When I took some 3 dozen screws out, and I pulled the cover off, I was surprised to find a big mouse nest inside, no mice of course. The service manual was shredded to pieces! Surprisingly no wires had been chewed on though. I started by removing some of the sheet-metal ducting inside, and removing the main blower fan. I want to find a use for it too, its a 3 speed 120v motor, with two blowers on each end. Under that was the heating element, and a smaller fan (which was quite flat). I was surprised when I found the heating element, but when I looked online, I found that the microwave is also a convection oven. Putting that aside, I started pulling out the whole wiring harness. There were a handful of thermal cutouts, all over the microwave. A handful of relays controlled the fans, lights, the HV transformer, and the heating element. All the relays were mounted on the main circuit-board, and powered by the control chip, a big 64-pin IC made by Samsung. Infact, it seems all the parts were made by Samsung, the fans, the transformer, the magnetron, the control board, and even the VFD display on the control board.

Pt2 coming soon!

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