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      On-demand appliance repair training videos for Professional Appliantologist members Over 30 hours (and growing!) of original, high quality appliance training webinars developed and given by yours truly are at your fingertips, on topics you won't find anywhere else. Fill in those knowledge gaps, strengthen those areas of uncertainty, and boost your skills. Watch on mobile or desktop at your convenience whenever, wherever.  Ultra Short Primer on Basic Electricity, Circuits, Ohm's Law, and Schematic Reading (Length: 1:04:48) Basic Refrigerator Troubleshooting (Length: 1:10:45) Schematic Reading Workshop, 10/2015 (Length 1:19:08) Troubleshooting Strategies for Computer-Controlled Appliances (Length: 48:34) Semiconductors and PN Junctions (Length: 1:04:37) Appliance Temperature Sensing Devices & Technology (Length: 1:27:33) Voltage Measurements, Meters, Ghost Voltages, and Triac-controlled Neutrals (Length: 1:29:32) Troubleshooting with Tech Sheets, Part 1, 4/2016 (Length: 1:09:26) Troubleshooting with Tech Sheets, Part 2, 4/2016 (Length: 1:21:11) Tech Sheet Review, 4/9/2016: Bosch Speed Cooker, Amana Refrigerator, GE Glass Cooktop Range (Length: 1:22:58) Pulse Width Modulated (PWM) Switches used in Samsung Switched Mode Power Supplies (SMPS) (Length: 27:07) PWM Computer Cooling Fan in a Whirlpool Refrigerator (Length: 14:53) Understanding AC Split-phase Household Power Supplies (Length: 52:41) Troubleshooting a Samsung Electric Dryer without Disassembly using Live Tests and the Schematic (Length: 22:47) Troubleshooting a Bosch Dishwasher No-Heat Problem using the Schematic and Live Tests (Length: 15:38) Linear Motors and Linear Compressors (Length: 55:54) Bi-directional PSC Drive Motor Systems in Whirlpool VM Washers (Length: 56:52) Appliance Service Call Structure and Troubleshooting Strategies (Length: 1:00:16) The Ten Step Troubleshooting Tango and Workshop Exercises (Length: 1:35:39) Troubleshooting Ten-Step Tango Advanced Workshop (Length: 1:32:06) Ten-Step Tango Troubleshooting Workshop: Refrigerators (Length: 1:35:57) Whirlpool Duet Washer Schematic Analysis & Whirlpool Dryer Moisture Sensor System (Length: 1:03:04) Neutral Vs. Ground, Inverter Microwave, Digital Communications, Loading Down in DC loads, and more! (Length: 1:14:45) Gas Oven Service Call After a Parts Changing Monkey (Length: 36:04) AFCI and GFCI Circuit Protection Technology (Length: 41:26) Troubleshooting Samsung Refrigerators and more (Length: 1:29:58) 3-way Valves and Dual Evaporator Refrigerators (Length: 1:15:45) Split-Phase Compressors and PTC Start Devices (Length: 1:11:57) Gas Dryer Ignition Systems (Length: 53:50) Refrigerator Sealed System Thermodynamics, Part 1 (Length: 43:07) Refrigerator Sealed System Thermodynamics, Part 2 (Length 1:09:09) To access these webinars and all the other info-goodies here at Appliantology, become a Professional Appliantologist today. If you need cost-effective, time-flexible, state-of-the-art appliance technical training, check out the Master Samurai Tech Academy.
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The Willie Method ™ for testing a microwave oven magnetron tube

Samurai Appliance Repair Man

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Sometimes, when you're troubleshooting a microwave, it can be tricky to tell whether or not the magnetron tube is bad. In the case with many GE microwaves, the magnetron can test good according to the filament resistance specifications yet fail when you're actually trying to get the damn thing to heat up your bagel.

One of the outstanding Master Appliantologists at Appliantology.org, Budget Appliance Repair (a.k.a., Willie) offered the following procedure for assessing the operational state of the magnetron:

Disconnect the two wires going to the magtube and set it for 20-30 seconds and run it. If no abnormal noises and no smell with magtube disconnected, (MAKE SURE BOTH WIRES THAT ARE DISCONNECTED FROM THE MAGTUBE ARE SAFELY AWAY FROM EVERYTHING AND MAKE SURE NOT TO GET NEAR THEM!!!!!!!), the most likely problem is a bad magtube.

If you short the capacitor, carefully with an insulated screwdriver after doing the above test and it sparks you can be pretty sure

the magtube is bad also.

If everything else checks OK and the smell is kind of a sweet plastic burning smell, (I don't know how else to explain it but once you've smell it once you will know for sure the next time), then it's for sure a bad magtube.

Source: Advantium 220 microwave electrical burning smell

And more from another post:

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.

Source: GE OTR Microwave JVM1871SH001

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applianceman18007260692

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I check the mag for continuity, if open it is bad. I check the mag for shorts between them 2 terminals and the frame of the mag. If I get a reading then it is bad. So what goes wrong?

Inside the mag is a filament like that of a light bulb. Over time the filament burns out or shorts out to the frame.

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Yes that's true, and sumtimes they will loose vacuume, and other times a magnet can crack.

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Yea today (my 2 cents) i measured resistance on the magnetron and it was good electrically and no shorts, but then i saw that the mags magnet had a hairline crack in it and was only drawing 5.4 amps i changed it and replaced it and the diode, so then the amps were drawing about 15 amps and heating water nicely.

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