• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

    Jake
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FIXED Samsung OTR Microwave MC17J8000CS Intermittent Power Issue

steve8092

Premium Member
Joined
Jan 19, 2020
Messages
4
Location
WI
Model Number
MC17J8000CS
Brand
Samsung
Age
1-5 years
My microwave is intermittently losing power. It is approximately 3 years old. I did some testing to try and isolate the issue (without pulling it out yet), and here is what I've found:

- If I run it for 30 seconds, it works fine (the first time). If I run for longer periods, or if I repeatedly run it at 30 seconds, it will eventually lose power.
- Sometimes this occurs at the end of the cycle, and sometimes at the beginning, where it essentially prevents it from starting.
- When I say 'loses power', it effectively loses power completely. The clock disappears, and the keypad does nothing.
- If I wait long enough, it will reset on its own. I also seem to be able to reset it by opening and closing the door.
- I tested it in a different outlet and it had the same issue, so the outlet seems fine.
- I may be wrong in this, but I feel like I do hear a bit of crackling when the unit is running.

Based on this, I'm suspecting that something is either overheating, or it thinks that something is overheating (i.e. a bad temperature sensor). Doing some reading, it might also just be a bad/burnt connection somewhere. I plan to pull it down and look for any obvious signs. Any thoughts?

Thanks in advance!
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
37,663
Location
Murray, Utah 84107, United States

steve8092

Premium Member
Joined
Jan 19, 2020
Messages
4
Location
WI
Thank you for the quick reply, and I apologize for my delayed response. As soon as I posted, the microwave sprang back to life, with no issues. Yesterday, it seems to have died almost completely. I've not yet pulled it down (will do so tonight), but I notice that smacking the top of the unit (not the bottom, front, or sides) gives it a quick blip of life. I'm not sure where each internal component is located, but I'll have a look and follow your advice.
 

steve8092

Premium Member
Joined
Jan 19, 2020
Messages
4
Location
WI
I found the culprit - or at least a culprit. There is a burnt connection on the thermal fuse above the cavity. It definitely fits with the initial ‘shutting down after heating’ and the later ‘smacking the top gives me a quick spark of power’. I’ve attached a pic. I’m hoping that this is the root cause and not a symptom; will have to order one and find out. I will also replace the connector, for good measure.

D5F93C8E-7129-44A1-ADD0-04B51865BA29.jpeg
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
37,663
Location
Murray, Utah 84107, United States

steve8092

Premium Member
Joined
Jan 19, 2020
Messages
4
Location
WI
Coincidentally enough, I had a couple of leftover thermal fuses from an order I placed a while back to replace one in my Samsung washer (lesson learned, don't buy Samsung anymore), and they appeared to have effectively the same rating as this one (I believe they are 5 degrees different). Given that I believe it acts as a flame sensor, I didn't figure that was significant. I replaced the fuse, and all is working again...for now. As a side note, I was actually able to do it without pulling the unit down by cutting out the small piece of plastic that was preventing me from getting to it (as it wasn't doing anything anyway).

Again, hopefully I've solved the root cause of the issue and not just a symptom. Thank you, Rick, for the suggestions.
 
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