Question about GE JVM1440 Microwave Oven

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HV diode producing resistance of 10 ohms.

Just tested the diode, transformer, capacitor, and magnitron in my GE jvm1441bh. Everything checks out but the diode.

The gallawa website says to set the ohmeter to read ohms @ a scale of R X 10,000 or higher. My meter just has one setting of 4000 ohms, which I suspect is just an auto range of 0 - 4000, so I'm afraid it isn't capable of reading resistances in the 50,000 - 200,000 range.

If that's the case is my multimeter simply providing a bad reading for the diode? It's reads 10 - 11 ohms across the anode/cathode.

Sorry for the ignorance, just not too familiar w/multimeters.

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  • dave_demaree Mar 07, 2009

    Appreciate the reply bob. Just a quick question.



    The gallawa site says that as long as you have a mm that utilizes a 6 volt battery or greater, you're ok. Mine uses a 9 volt battery.



    The website doesn't mention setting up a test circuit, just attaching the probes to either end of the diode and reading resistance. Is that not correct?

  • dave_demaree Mar 08, 2009

    Thanks for the clarification Bob. This microwave is only 3 years old, so I will have to use your method. To clarify, are you just hooking the diode in series with one of the battery terminals, then attaching the mm probe to the free end of the diode, and attaching the other mm probe to the free battery terminal?



    I tried that and I got a reading of 9.3 v both ways. When hooking the diode in parallel with the battery terminals, I got a reading of 5 volts one way, and three volts when reversed.



    Would this denote a faulty diode?

  • jpal012 Mar 26, 2009

    I have a jvm1440 ge microwave that doesn't heat the food but everything else works.The capacitor did not spark when I went to discharge it.I used your diode test with the 9volt battery . It tested good. The fuse also tested ok. I would like to test the transformer but I havent found a good test method yet also its pretty buried in the oven. If you know a good transformer test I would definitly be interested. Thanks

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You cannot check a microwave diode with just a mutli meter . you have to make a test jig take a 9 volt battery and a meter with dc volt scale set up the meter just like you would test a 9v battery .with me so far ? now remove one lead from the battery and insert the diode between the battery and the test lead .......take a reading . now reverse the diode take a reading ........ i just tested a diode before writeing this and this is what i got my battey volts where 9.2 v whith the diode inserted i got 7volts . reversing it i got .02 volts dc . a diode is a one way valve and mine is good because it passed curent only one way ...yours should be about the same ....... if you understand this please leave me 4 stars ! i even went out in the shop and tested a diode for you just to make sure my answer was correct

Posted on Mar 07, 2009

  • BOB  BROWER
    BOB BROWER Mar 08, 2009

    there was a change in diode type . i for got to ask you how old your microwave is . if your microwave was made before around 1985 you can use the meter with the batterys inside . if it was bade after around 1986 its a very hv diode and will require the 9v battery test jig ..... there where 3 changes to the diodes 1966 to 1972 test with any meter 1973 -1986 any swing meter with 6 v battery (do not use digital) 1986 to present must use special equipment or homemade eqipment with 9v battery or higher and a dc volmeter ....... hope this helps , sorry i did not know you had an older microwave , i dont see them anymore in my shop and forget there are a still a few out there .... good luck

  • BOB  BROWER
    BOB BROWER Mar 08, 2009

    the diode is in series with one battery connection and a meter lead eather one will do . then turn the diode over , you should be reading the battery volts through the diode

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PLEASE READ HERE HOW TO DISCHARGE YOUR CAPACITOR AND SAFETY PRECAUTIONS BEFORE DOING ANYTHING!!!

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CLICK FOR IMAGE

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