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Ralph III 03-13-2013 02:39 PM

Microwave won't heat, help please....
 
3 Attachment(s)
Hello,

I have a GE over-the-range Microwave (JVM1540SM2SS) that will not heat and need some help in order to fix it myself. Everything else works fine on the microwave, btw. The same thing happened about 3 years ago at which time a service center replaced the magnetron. I assume it is the same issue but would like some insight in testing some things in affirming that....

1) I attempted to discharge the capacitor via an extra hot lead (tab) and a chasis ground; with use of a pigtail and lightbulb. It didn't show any charge as nor did my voltometer when applied?

I powered up the microwave just prior to testing, btw. FYI, I chose not to remove the wires from the capacitor in fear of damaging them but can if absolutely necessary?

2) Should I test the diode which grounds the capacitor to the chasis, as seen in the first picture?

3) Is there any other plausible item that should be tested or is the magnetron just the obvious issue? If the later, can you recommend an online supplier where I can get a magnetron from?

Thanks,
Ralph

TheBobmanNH 03-13-2013 02:46 PM

"Everything else works fine on the microwave."

Isn't that the only thing microwaves do? ;)

djlandkpl 03-13-2013 03:27 PM

It could be one of the safety switches that's preventing the magnetron from working. I don't have a GE. Mine is a Wolf but I believe the guts are made by Sharp. My oven work look like its working but it would not heat the food. Turns out one of the safety switches was getting hot and it shorted out. There could be 3 or 4 of them in your oven. Look around the door area for them. Might look like this:

https://encrypted-tbn0.gstatic.com/i...5R9Kvli6TGrvoA

hardwareman 03-13-2013 05:08 PM

microwave won't heat: it could be several things. The only way to narrow it down is to do live power tests inside the micro. Are you comfortable with that? If so I can walk you through it, but be warned that there is 4000 volts of electricity going to some parts! Do you have a digital volt meter?

ktkelly 03-13-2013 05:12 PM

I'd start with the door switches.

Might take no more than a visual inspection.



Very common problem with GE microwaves.

Ralph III 03-13-2013 05:48 PM

Thanks for the quick replies!


Quote:

Originally Posted by hardwareman (Post 1136570)
microwave won't heat: it could be several things. The only way to narrow it down is to do live power tests inside the micro. Are you comfortable with that? If so I can walk you through it, but be warned that there is 4000 volts of electricity going to some parts! Do you have a digital volt meter?

I have a couple of digital voltmeters but the one I use most often is this GreenLee CM-600. Just tell me what you'd like tested and don't worry safety first. I've done construction and electrical most my life and do understand the amount of power capacitors (also a photographer) can have. Note: Not as a contractor but as a homebuilder and as my Dad was a contractor/engineer.

Do you need more pictures of the unit so I know exactly what you are talking about?

Ralph

hardwareman 03-13-2013 06:35 PM

first things first, do you have the wiring diagram handy? No biggy if you don't we can still do this. Microwaves are divided into 2 sections, the low voltage side( 110volts) and the high voltage. Low voltage will include the control panel, door switches and the low side of the step up transformer. We can eliminate the low voltage side by taking a voltage reading at the low side of the transformer. Here is were the diagram would be nice to have since there will be 4 wires on the transformer and you don't want to get the wrong side. By the looks of yours ( I can only see half of it) the white wire on the bottom and I would assume a black wire that I can't see is going to be your low side. Check for 110 volts here, if you have it then everything on the low voltage side is working and the problem will be on the high side, either the diode, the capacitor or the mag tube.

Ralph III 03-13-2013 06:53 PM

2 Attachment(s)
Quote:

Originally Posted by hardwareman (Post 1136638)
first things first, do you have the wiring diagram handy? No biggy if you don't we can still do this. Microwaves are divided into 2 sections, the low voltage side( 110volts) and the high voltage. Low voltage will include the control panel, door switches and the low side of the step up transformer. We can eliminate the low voltage side by taking a voltage reading at the low side of the transformer. Here is were the diagram would be nice to have since there will be 4 wires on the transformer and you don't want to get the wrong side. By the looks of yours ( I can only see half of it) the white wire on the bottom and I would assume a black wire that I can't see is going to be your low side. Check for 110 volts here, if you have it then everything on the low voltage side is working and the problem will be on the high side, either the diode, the capacitor or the mag tube.

Thanks Hardwareman. Here are a couple of more pictures to insure I have everything noted correctly. There is a black and white wire coming off of what I assume is the microwave transformer. I marked the Diode with a "D" as it comes off of the capacitor and is then grounded. I will try and post a pic of the schematics in a little bit, if I can find it. Note: I can only read very very simple schematics. I leave that stuff to the experts....

Ralph

Ralph III 03-13-2013 08:01 PM

2 Attachment(s)
Hardwareman. I tested voltage on both the white and black wires coming off of the transformer, denoted "B" and "W" in picture above (post #8). No power showed on either one.

In testing, I plugged the unit in and checked for power on each leg with use of a chasis ground. I then used both probes on my voltmeter to check both legs simultaneously, as when testing for 240v, and still nothing showed. I tested my voltmeter on the outlet and it is working properly 120v. Note: I didn't actually start the unit but just had it plugged in.


FYI: I cannot find any schematics listed anywhere (bottom/top/sides/Interior). There is only a warning label in regards to some switches as shown below.

What else should I test?

Ralph

funfool 03-13-2013 08:09 PM

Just saying, I had a really good friend that wanted to fix his broken microwave.
He was electrocuted and died instantly.
He had a wonderful funeral, over 200 showed up. He left behind a beautiful wife and 2 young boys.

How important is this microwave to you?

hardwareman 03-13-2013 08:23 PM

black wire/white wire on transformer, hook up your meter to those two wires. Be safe and jab your leads into the wire protector so it holds your leads and you can get your hands out of there. Now turn microwave on and check for 110 volts. Safety is very important here, if you do not feel comfortable with this then please stop.

Ralph III 03-13-2013 09:08 PM

Quote:

Originally Posted by funfool (Post 1136715)
Just saying, I had a really good friend that wanted to fix his broken microwave.
He was electrocuted and died instantly.
He had a wonderful funeral, over 200 showed up. He left behind a beautiful wife and 2 young boys.

How important is this microwave to you?

I understand where you are coming from and if at any time I ever feel uncomfortable then beleive me you, I will not test.

Safety has always been my first priority as I was raised working around electricity all my life...

Ralph III 03-13-2013 09:13 PM

Quote:

Originally Posted by hardwareman (Post 1136730)
black wire/white wire on transformer, hook up your meter to those two wires. Be safe and jab your leads into the wire protector so it holds your leads and you can get your hands out of there. Now turn microwave on and check for 110 volts. Safety is very important here, if you do not feel comfortable with this then please stop.

CORRECTION: I AM GETTING 120V AT THE TRANSFORMER!

I tested as you stated; hooked up voltmeter to black and white simultaneously, turned microwave on, and do get 120v reading.

I PREVIOUSLY STATED I WASN'T GETTING ANY VOLTAGE BUT IT WAS DUE TO THE DOOR BEING AJAR AND CONSEQUENTLY NOT MAKING GOOD CONTACT WITH SWITCH.

Ralph

hardwareman 03-13-2013 10:09 PM

no voltage means you either have a bad door switch, remove each one a do a continuity check, or a bad board. Check the switches, I'm sure you'll find one bad.

Ralph III 03-13-2013 11:58 PM

Quote:

Originally Posted by hardwareman (Post 1136815)
no voltage means you either have a bad door switch, remove each one a do a continuity check, or a bad board. Check the switches, I'm sure you'll find one bad.

UPDATE:

In looking at the switches I noticed one switch wasn't closing properly as I had the microwave resting partially on the door.

Upon repositioning the microwave and retesting the transformer, I do indeed show 120v.

What next?

Thanks,
Ralph


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