Testing a microwave capacitor
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- Опубліковано 1 жов 2024
- Testing your microwave capacitor. Before testing, please ensure that the capacitor has been discharged. For safely discharging your capacitor, please watch our video on discharging your microwave capacitor.
Here's our microwave capacitor, and we can see it's clearly labeled on the side, 0.95 µF, standing for microfarad. And next to that plus or minus 3%. This means that its reading should fall within 3% of the 0.95.
To test your microwave capacitor, set your multimeter to capacitance. This will look like two parentheses facing away from each other. Next, take your meter leads and place each lead on one set of the capacitor's terminals. Here we can see the meter reading 944.7 nF standing for a nano farad, which would be the equivalent of 0.95 microfarads. If the capacitor is out of range by the allowed amount given on the label or the meter reads OL at any time, the capacitor has failed and needs to be replaced.
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I have a microwave capacitor that is rated for .91 +/-3%. Its reading .944. That puts it at 3.7% over the rating and .7% out of spec. Is .7% out of spec going to prevent my microwave from functioning? What's the typical reading of a failed capacitor, is it close or really far off spec?
As far as those readings go the microwave should run just fine. When the capacitor fails It normally will be out of spec by a large margin. When the capacitor shorts it basically becomes a piece of wire and the microwave will run over current and blow a fuse or trip a breaker. When the capacitor opens it will not allow any current at all. The unit will run but not heat food.
In the UK ( 230 Volts AC ) .... another way to test , is to wire your 1 μF capacitor in series with a 25 Watt , 230 Volt Tungsten filament bulb ... connect the whole lot across the mains ... the bulb should glow with an orange similar to a tube ( valve ) heater from a vintage radio ( makes a good nightlight as well ) ! ............ DAVE™🛑
Thanks Dave! Awesome to hear from you in the UK!
would have been nice to have a few caps to show in spec, out of spec, OL etc.
Hello! Thank you for the feedback. We will certainly keep this in mind for future instructional content. In the interim, if your meter reads outside the suggest value on the cap, it will need replaced. :)