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Author Topic: Microwave unit Will not Run Correctly  (Read 868 times)

Offline wpollock

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Microwave unit Will not Run Correctly
« on: January 05, 2019, 04:26:25 PM »

 I have a KCMS2055 SSS-1 microwave unit which is notorious for having door switches go bad. The unit has power but will not turn the turntable/run after entering a use time,closing the door and hitting the start button.However,I can ever so slightly push in on the door opener and the unit will engage. Service companies have changed door switches on four different calls and when I ask them why the same issue recurs they say the switches are just a cheap and unreliable part.This unit is in a home I rent and I would like to consider replacing the switch(es) myself.I am no professional repair person but have watched how the unit is removed from the cabinet and how the casing is removed. Does it require a special tool to remove the screws holding the switches in place or can I use a standard phillips head screwdriver? Also,does the unit store voltage after being unplugged that I need to dissipate before removing the switches? I do not recall seeing any service technician cross grounding anything for this purpose when they have replaced switches on this unit. Any input is appreciated and thanks.


Re: Unable To Remove Oven Door Per Manual
Reply #4 on: December 26, 2018, 10:57:43 PM
Quote
They're using crappy switches. I use QBP switches with no problems. Use 28QBP0495 if you have 3/16" terminals and 28QBP0496 if you have 1/4" terminals. The HV capacitor can potentially hold a lethal charge but it has a bleeder resistor to drain the charge while not in use. I discharge the capacitor by shorting the terminals with a copper wire loop held with insulated pliers.
Last Edit: December 26, 2018, 10:58:49 PM by tgoods

As suggested by tgoods and a switch bag left by the last repair tech I ordered ERP switches and they have arrived. The switch configuration on my unit uses the Common (with black and pink wires) and Normally Open(with green,yellow and white and tan wires) switch terminals. If I understand Electricity 101 correctly, a Normally Open switch tests good when the switch is activated.In my case this will be when the door is closed and the latch assembly has all three switch buttons depressed/closed. If this is correct can I test each switch by attaching gator clips connected to my multimeter to the Common and Normally Open switch terminals without removing any of the wiring terminal clips coming from the microwave? Pictures are attached showing the bottom and middle switches in one and the top switch in another. I will have to remove the terminal clip from the top switch because it is a single piece unit that completely covers the switch terminals.

Offline wpollock

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Re: Microwave unit Will not Run Correctly
« Reply #1 on: January 08, 2019, 05:21:42 PM »
So I am posting to ask if I would any damage to the microwave if I were to plug it into a power source and run it without installing the outer casing/Of course this implies i have the common sense to not touch any exposed electrically charged wires,terminals etc. while it is plugged in and to unplug it and discharge the capacitor before doing so.

Thanks

Offline olyteddy

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Re: Microwave unit Will not Run Correctly
« Reply #2 on: January 08, 2019, 10:22:14 PM »
Shouldn't run it long as the cooling fan usually counts on the case to direct the airflow.

Offline wpollock

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Re: Microwave unit Will not Run Correctly
« Reply #3 on: January 11, 2019, 09:49:15 AM »
Is there anyone active right now on the forum and who can provide the correct way to reinstall the middle door switch shown in the attached picture without breaking the door latch assembly?It doesn't appear to have a tab like the bottom switch that is pushed to allow the switch to pivot out of and into operating position

Thanks

Offline wpollock

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Re: Microwave unit Will not Run Correctly
« Reply #4 on: January 11, 2019, 12:42:19 PM »
A couple of more pictures showing the door latch assembly with the middle switch completely removed and one with the switch partially installed.The more I move the switch down(towards its operational position)there is more resistance which I assume is due to the switch contacting the door latch assembly(particularly the round white piece) on its back side

Offline wpollock

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  • Member Since: Sep 2015
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Re: Microwave unit Will not Run Correctly
« Reply #5 on: January 11, 2019, 06:53:48 PM »
So I was able to get the middle switch reinstalled and followed by the outer cover.Powered up the unit and it is running/heating just fine. Based on its history I have no doubt another switch will go bad,just a matter of when. I am making copious notes in case and hope to be more efficient. Thanks for all the replies and help.