Vintage General Electric 1200W Microwave Oven

Got hold of a old vintage General Electric 1200 microwave overn from the rag and bone man. Did not waste time in opening it up.  Here is the innards, the classic magnetron, the high voltage transformer that weight about 7kg, the high voltage rectifier diode, the electrommechanical time, the cooling fan, the cooking chamber light which is an old fashion 20W incandescent light bulb, the turntable motor, the microswitches that turn off the microwave oven when the door is open, the  over temperature cut off sensor mounted on the magnetron itself. 

Note the mica sheet covering the microwave waveguide opening in the cooking chamber. This is actually a bad design as it exposed the mica sheet to the consumer risking food contamination.

Interesting fact to note is that although General Electric do make magnetrons once, they are now using a LG Electronics ( South Korea )  magnetron, so is the high voltage 1uF capacitor.

In vintage microwave oven like this which uses a high voltage transformer, the cooking microwave power is actually controlled by turning the magnetron on and off at regular intervals. This actually does not gives very precise cooking. Modern microwave oven uses a electronic inverter to supply high voltage to the microwave and the microwave power in this case is controlled by varying the high voltage output pulses.

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Inside 150W Metal Halide Lamp Replaced By Led Bulb

LED lighting has finally became bright enough to replace this 150W metal halide indoor floodlight. I dismantle the metal halide lamp to have a look.  These pictures are the inside components of the metal halide lamp.

The 150W metal halide ballast, the metal halide power factor capacitor, the  metal halide ignitor and the 270K bleeder resister.  Note the metal halide ballast connection diagram. Essentially the ignitor is wire in parallel to the metal halide lamp to give it the 3KV or more kick it needs to startup. The whole ballast assembly weight about 3Kg, really vintage technology as it is electric ballast. 

Although electronic ballast are available,  more efficient LED have replace metal halide lamps especially below 250W.

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