Microwave not turning on or turning on when door opens? Here's how to fix it from start to finish--unplug it, open it, discharge capacitor, test, remove and replace switch.
Many thanks for posting this video. It is very informative. Special thanks for the Capacitor Discharge Bleed Tool info. Easy to make and is a professional approach to safely handling Capacitor Circuits. Top job :)
Misterfixit is totally correct in what he says, there is a High Voltage Capacitor inside the Microwave. This certainly does hold a charge in many microwaves & should be Properly Discharged before attempting to work on a Microwave. Although many (Not all) have a Bleed resistor, they can & do at times go open circuit & should not be relied on. It takes a matter of seconds to discharge the cap & then you know it's safe.
great video, most out there forget to tell you about the capacitor ... what size resistor do you use? is a Caddock MG745 200M MEG Ω 15kv 5W 1% overkill - or just being safe? because that's what I have on hand and you said thousands of volts. Another video out here has a comment about using a bulb, socket and two clips in lieu of the resistor. And if the microwave has sat for a while, isn't the capacitor partially or fully discharged already? thanks!
Thanks for the comments. It’s a 150k ohm 25w resistor. Stick with the higher wattage (10w +) resistors that can handle potential high voltage without zapping between terminals-there’s some on ebay for ~$10. . Yes capacitors can discharge over time when unplugged but can you tell? Don’t use a light bulb! That’s for lower voltages and much, much smaller capacitors on circuit boards etc.
most appliance repair stores carry these switches as they are common among many microwaves, paper shredders, & refrigerators. Omron is the typical supplier. Omron_069-150_HR_0
I don't think there is any capacitor in the Microwave that store energy to shock you. Only the old type of TV does. It is a straight forward like the IRON. There is NO ENERGY STORED. If there is any energy stored, it will SPARK when you touch it with the discharge device (here you have the high watt resistor) but as I said, there is no energy stored in the microwave. When you unplugged it, it is dead. No shock, no spark, but you can do your way for caution only, however, if you said microwave has stored energy, it is not correct.
I wouldn't expect a capacitor to be safe as they were designed to store energy, it isn't worth the risk, to just assume it drains. Electronics are complex and you don't want to damage components or risk your life or health. My microwave has a high voltage, as do many and it isn't worth the risk to assume parasitic components are operative. electronics.stackexchange.com/questions/32529/do-capacitors-automatically-release-their-energy-over-time
