Question about Panasonic NN-T990SA Microwave Oven

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My microwave just switches off in 5 seconds. how do i trouble shoot it?

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Check the thermistor on the side of the magnetron tubes body, its usually held on by 2 small screws,it's about 1/2" round and has 2 wires on tabs coming out of it, remove thermistor & wires and clip on ohm-meter and heat the thermistor with a match and see how fast it clicks and the meter goes to infinite from a short circuit which will when in circuit shut power off to the tube it's a type of temperature safety switch for the magnetron tube and it or the tube are faulty, also carefully check the tubes body after operation and cutout and see how hot tube is,it could be the tube going out,but i think it will be the thermistor in the end because if the tube gets that hot that quick it would blow the units fuse due to excessive current draw

Posted on Nov 19, 2009


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