GE OTR Microwave JVM1871SH001

[Adirondack Bob]

Trying to diagnose no heat in a GE OTR MICROWAVE JVM1871SH001. The unit comes on and the turntable works but no cooking. The diode is ok, all door switches test ok, took capacitor out and tested with Fluke on cap. setting and it was spot on according the range listed on capacitor. Next I'm trying to ohm the HV transformer but not sure how. I took the red lead and the white lead off the capacitor and tried to ohm it that way and got 0ohms. Is that the correct way to it or not? Also how to test the magnatron without taking the whole unit down. Thanks, Bob.

[Scottthewolf]

it's a GE and you have tested almost everything but the Magnetron. It's the magnetron.

[Adirondack Bob]

Thanks, yes tested almost everything but transformer and mag. Also when I arrived I could smell a slight electrical burn. Thanks

[Budget Appliance Repair]

Just had a 1989 Whirlpool range hood microwave doing the same thing. Do you also notice what seems to be a louder then normal buzzing/vibrating noise.

If so, take an amp reading and see how many amps the unit is drawing, (the one I worked on only came up to around 2.4 - 2.6 amps), and you could smell that burning magtube smell after a minute or so of running.

Then pull the two wires of the magtube and make sure the are away from everything and start it up again and see what the amp reading is, (I got around 5.6 amps and the heavy vibration noise wasn't there any more).

A good working microwave will draw about 2 - 3 amps when first started and in about 3 seconds, (after the filament is warmed up), you will see the amp draw come up the the full 11 - 12 amps that a microwave will pull. If you listen carefully when a magtube ramps up power, (you will here a real light buzz noise after the filament warms up), you will see how that corresponds to the amp raise.

[Adirondack Bob]

Thanks Guys, Went back tonight and replaced the magnatron. Microwave is working as good as new! Thanks Again, Bob