Question about Microwave Ovens
Our microwave died suddenly. No Lamps or power indication at all. Power to the electrical outlet it is plugged into is good. Is there any internal fuse or circuit breaker that I can check before paying for a service call?
A microwave can be dead for many reasons.
It may be the fuse, which is usually located behind the grille or on the floor of the oven behind the control panel or between the door switches.
If the fuse is good, it may be an open oven thermal cutout (TCO) on the top of the oven cavity / body or an open thermal fuse on or above the magnetron.
These should read closed (virtually zero) on a continuity check.
If it went dead almost immediately after pressing the Start pad, that's usually a shorted high-voltage capacitor.
If it went dead a few seconds after pressing the Start pad, that's usually a failing high-voltage transformer.
If it went dead or when you plugged it in or opened or closed the door, then there's a problem with a door switch or door switch mount.
If it's intermittent or random, it may be a bad connection, usually on the control board or a loose fuse holder, or even an intermittent fuse.
You should do a continuity test on the fuse while it's in the holder (with the microwave unplugged, of course) then turn the fuse by hand or take it out and put it back in, then test it again.
If you remove the fuse, then press the meter leads against the ends, it can allow internal contact to be made and make a bad fuse appear to be good.
If you or someone you know decide to look into it, we have critical safety information and disassembly information at our site, and our link is at our listing here on FixYa.
You can usually find exploded views and order parts by entering your model number here at the Sears parts site but the best place to order Sharp parts is Tritronics.
We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.
Posted on Oct 13, 2008
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Posted on Jan 02, 2017
Tips for a great answer:
Unplug your microwave and turn it around and remove the screws holding cover on and then remove the cover. Look for where the power cord goes into the back of the unit and follow the black wire from the cord to where it ends. It should stop an either a circuit board or a fuse holder. Make sure that you replace the fuse with the same amperage fuse as what you take out. You will find the amp rating stamped on one of the silver collars on each end of the fuse. Good luck!
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