Does anyone have the installation instructions for replacing the fuse in the Kenmore Microwave model number 790.80339310. I took off the grill on the top and cannot see where the fuse is located or how to get the control panel down to see if I can see it. Also where is the capacitor to discharge. PLEASE HELP!
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Couldn't find a service manual, but here's a link to a parts diagram that shows the location of all the parts.
The fuse is part #34 and the HV capacitor is part #51.
Fuses rarely if ever, fail of their own accord. There is usually a contributing factor that causes them to fail i.e. excessive current flow through the fuse due to a fault in the device. So you may find that even if you replace it, the replacement fuse may fail immediately once the oven is started.
If it does then fortunately there's a wiring diagram in the link provided above which will help to find the problem of why it has blown.
A lot of the times with microwave ovens, the fuse blows due to a problem with the door interlock switches failing to function correctly either due to them becoming loose or perhaps their contacts being welded closed due mainly to people, over a period of time, stopping the oven by opening the door instead of using the control panel buttons to stop it. This causes their contacts to arc and weld shut as the power flowing through them, hasn't been turned off by the control panel causing arcing as the contacts open.
If the interlocks are OK, further testing would be required to find out what's wrong.
Be safety aware when working in microwave ovens. The HV capacitor can store >5000V DC for months, even if the power has been disconnected for this length of time. This amount of voltage can seriously injure you. The HV capacitor needs to be discharged correctly as soon as it can be accessed, after the oven's cover has been removed and before commencing any further work inside the oven,
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No heat and everything else working OK, indicates a problem with the HV (high voltage) circuit in the oven.
This could be the R2 relay on the control board, the HV transformer, the HV diode, the HV capacitor, the magnetron or the wiring between these components.
The R2 relay contacts when operated connect the AC power to the HV transformer primary winding. The transformer in conjunction with the HV diode and the HV capacitor generate the necessary voltage for the magnetron which produces the microwaves which heat and cooks the food as they pass through it.
Here's a link that describes how to test each of these components in the oven.
Here's a link to a parts supplier that is useful as it has the wiring diagram for the oven as well.
If you find a component which is causing the problem, locate it in the parts list to find the manufacturer's part number listed with the part. Then search online using the part number only to find suppliers that suit you best.
FYI your oven is a Frigidaire oven made for Kenmore. Just so you're not surprised when the parts show up as Frigidaire parts. As best as I can tell, Kenmore doesn't make appliances but presumably orders them from other makers e.g. LG, Whirlpool, Frigidaire etc and then renames them.
Also see the safety notice in the Chosen Solution above, regarding working in microwave ovens.
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Fuse was popped on mine. Easy to fix. Mine happened from surge using too many appliances off same circuit.
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Hi @wesclontz,
Just curious if the house fuse (or breaker) that fed the circuit blew as well?
I had the same problem and I'm thinking about changing the fuse. my breaker did pop on my breaker panel? Does that mean anything
What is the make and model number of the microwave oven?
Normally the only way that a power box fuse (or breaker) should blow (or trip) if there is an appliance etc connected to it has for whatever reason drawn too much current is if it hasn't got a fuse in it e.g. some kitchen electric kettles or if it has a fuse then perhaps there's already nearly the maximum amount of load on the power fuse already due to other appliances/devices connected to outlets supplied by the fuse that are turned on at the time and when the appliance develops a problem where it draws too much current then perhaps not only will the fuse in the appliance blow but the fuse (breaker) in the power box as well.
Electrical wiring standards are different for different countries so it varies as to how many power outlets are allowed to be connected to each power fuse in the power box.
It is a Kenmore 790.80339310. The first couple of times it tripped the breaker when opening the mw door. After resetting it would work for a day of two. Now it seems to operate fine but no heat?
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If all seems OK but no heat the obvious culprit is generally the magnetron. But in my case it was not the magnetron itself but the magnetron socket which I opened and discovered that the RF capacitor had shorted. There are two of these - one in each leg - and each in parallel with a (in my case 10Mohm) resistor. Easy to detect with a multimeter - just compare the two legs. I got a 'used' magnatron (not even the same as mine) for free from my domestic appliances repair shop and with a little modification replaced my old socket with this one. Just to be thorough I also replaced the fuse and HV diode. Still going strong after 4 years. PS: magnetron sockets are freely available online or from a DAR shop.
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My microwave operates but there is a terrible noise when it runs. Any ideas?
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What's the make and model number of your microwave?
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Hi @fines13109
Check the answers in this thread and see if one of them is applicable to your oven
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The fuses on these microwaves cannot be accessed without removing the microwave from the wall. Once you have it down, you need to remove all the screws holding the black housing on (including two underneath on each side). Then you can take that whole housing off. From there, the fuse is simple to access.
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Unplug the microwave from the power source, and give it some time to discharge any stored electrical energy. This is akin to waiting for a storm to pass before venturing out onto the sea.
Next, remove the microwave's outer casing. Much like an archaeologist delicately unearthing a precious artifact, use a screwdriver to remove the screws that hold the casing in place. This reveals the inner workings of the microwave, including the fuse.
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