Troubleshoot modern appliances with confidence…

Click here to check out our structured, online appliance repair training courses for rookies and experienced techs.

FAQs | Repair Videos | Academy | Newsletter | Podcast | Contact

Stay connected with us...

Samurai on Facebook - become a fan today! Sign up for our free newsletter and keep up with all things Appliantology. Subscribe to our YouTube channel for lots of appliance repair tips and help! Follow the Samurai on Twitter and get timely morsels of Appliantological Wisdom! Subscribe to our MST Radio podcast to learn secrets of the trade.
  • Announcements

    • Samurai Appliance Repair Man

      Webinar Recordings Index Page   11/07/2017

      On-demand appliance repair training videos for Professional Appliantologist members Over 30 hours (and growing!) of original, high quality appliance training webinars developed and given by yours truly are at your fingertips, on topics you won't find anywhere else. Fill in those knowledge gaps, strengthen those areas of uncertainty, and boost your skills. Watch on mobile or desktop at your convenience whenever, wherever.  Ultra Short Primer on Basic Electricity, Circuits, Ohm's Law, and Schematic Reading (Length: 1:04:48) Basic Refrigerator Troubleshooting (Length: 1:10:45) Schematic Reading Workshop, 10/2015 (Length 1:19:08) Troubleshooting Strategies for Computer-Controlled Appliances (Length: 48:34) Semiconductors and PN Junctions (Length: 1:04:37) Appliance Temperature Sensing Devices & Technology (Length: 1:27:33) Voltage Measurements, Meters, Ghost Voltages, and Triac-controlled Neutrals (Length: 1:29:32) Troubleshooting with Tech Sheets, Part 1, 4/2016 (Length: 1:09:26) Troubleshooting with Tech Sheets, Part 2, 4/2016 (Length: 1:21:11) Tech Sheet Review, 4/9/2016: Bosch Speed Cooker, Amana Refrigerator, GE Glass Cooktop Range (Length: 1:22:58) Pulse Width Modulated (PWM) Switches used in Samsung Switched Mode Power Supplies (SMPS) (Length: 27:07) PWM Computer Cooling Fan in a Whirlpool Refrigerator (Length: 14:53) Understanding AC Split-phase Household Power Supplies (Length: 52:41) Troubleshooting a Samsung Electric Dryer without Disassembly using Live Tests and the Schematic (Length: 22:47) Troubleshooting a Bosch Dishwasher No-Heat Problem using the Schematic and Live Tests (Length: 15:38) Linear Motors and Linear Compressors (Length: 55:54) Bi-directional PSC Drive Motor Systems in Whirlpool VM Washers (Length: 56:52) Appliance Service Call Structure and Troubleshooting Strategies (Length: 1:00:16) The Ten Step Troubleshooting Tango and Workshop Exercises (Length: 1:35:39) Troubleshooting Ten-Step Tango Advanced Workshop (Length: 1:32:06) Ten-Step Tango Troubleshooting Workshop: Refrigerators (Length: 1:35:57) Whirlpool Duet Washer Schematic Analysis & Whirlpool Dryer Moisture Sensor System (Length: 1:03:04) Neutral Vs. Ground, Inverter Microwave, Digital Communications, Loading Down in DC loads, and more! (Length: 1:14:45) Gas Oven Service Call After a Parts Changing Monkey (Length: 36:04) AFCI and GFCI Circuit Protection Technology (Length: 41:26) Troubleshooting Samsung Refrigerators and more (Length: 1:29:58) 3-way Valves and Dual Evaporator Refrigerators (Length: 1:15:45) Split-Phase Compressors and PTC Start Devices (Length: 1:11:57) Gas Dryer Ignition Systems (Length: 53:50) Refrigerator Sealed System Thermodynamics, Part 1 (Length: 43:07) Refrigerator Sealed System Thermodynamics, Part 2 (Length: 1:09:09) Refrigerator Sealed System Thermodynamics, Part 3 (Length: 1:11:56) Refrigerator Sealed System Thermodynamics, Part 4 (Length: 37:45) Refrigerator Sealed System Thermodynamics, Part 5 (Length: 16:35) To access these webinars and all the other info-goodies here at Appliantology, become a Professional Appliantologist today. If you need cost-effective, time-flexible, state-of-the-art appliance technical training, check out the Master Samurai Tech Academy.
    • Son of Samurai

      INCREDIBLE DEAL: Introducing the Master Samurai Tech Alumni Program   01/17/2018

      Certified graduates of our Fundamentals course over at Master Samurai Tech can now apply for membership at Appliantology 100% FREE! They'll have all of the benefits available to Professional Appliantologist members at none of the cost. How do you get in on this steal of a deal? Read the post below to find out!  

Dead Samsung OTR Microwave ME18H704SFS

Recommended Posts

Totally dead Samsung OTR Microwave Mod ME18H704SFS Ser 07867WTF700650E.
This unit is about 16 months old, it belongs to my son.  It has worked fine since we installed it.
He went away for the weekend, came back home and the unit was totally dead.  Nothing.  No lights, no panel, no fan. DEAD. Tried a new outlet on a different, (known good) circuit.  Same thing. DEAD !!.  there was no bad weather or any other signs of electrical malfunction in the house. It is on a dedicated 20 A circuit. 
I couldn't find a schematic for it.  I guess gone are the days of including one with the appliances. 
After properly discharging the HV cap, I tested as many components as I could easily get to.
Fuses on the power board were good. All (I think I found 3) thermal switches/cutouts had continuity.  I am not sure I was able to get to ALL the door switches (or for that matter, all the contacts on all the door switches) but the ones I was able to get to tested fine on open/close. 
I was able to test for AC up to the power board. I did not go into any board components further. 
When I was testing the thermal cutouts and the door switches, I was careful to remove at least one connect or from each before testing it.  All connectors looked fine, and disconnected / reconnected without incident. EXCEPT the one on the thermal cutout for the magnetron. 
The thermal cutout on the magnetron had one normal looking connector, and one that was badly heat discolored. possibly slightly melted and because of it's location, I was not able to get the required "oomph" on it to disconnect it. I tried wiggling it, pulling it, I tried some needle nose pliers. I just couldn't get a decent grip on it.  So I disconnected the normal, unblemished one, and tested continuity fine via the contacts on the cutout itself, NOT via the connector crimp.
At this point I had gone as far as I could/wanted to without a schematic.  
As a "last ditch" effort before calling it a day, I plugged it back in and all was well.  It fired right up, heated fine.  I remounted it on the wall and it's been good for the last 24 hours.
My guess is that one of the connectors I wiggled/removed/reattached etc while testing fixed the issue.  Which one?  My guess is probably the discolored one on the mag cutout.  But who know at this point.  Next time I'll test one thing at a time and try to fire it up each time.
Any other thoughts, comments or suggestions?

Share this post

Link to post
Share on other sites

Need appliance parts? Call 877-803-7957 now!


To fix this microwave I used schematic and wiring diagram from model ME21F707MJT. To test if the wiring and TCO on top of the magnetron is good or bad test the continuity between the bare connector on the TCO on the top left behind the control panel, which is for the chamber, to the black wire with a white connector on the lower door interlock behind the control panel. It is easiest to remove the connector and test directly. Continuity shows it good or bad. My microwave went out after 1.5 years and using an inspection camera it was easy to see the burnt connector. Order KSD-150LC thermal cut out.

Share this post

Link to post
Share on other sites

Power confirmed to the board and it is dead? If you're reading the input into the board transformer, then most likely the board

Share this post

Link to post
Share on other sites

responding to  pjw73nh -- not all the thermostats are supposed to be closed.  There is one that is normally in the "open" position and when it heats up it runs the fan to cool down the unit. That one is on the base of the microwave below the control board, towards the left.

Share this post

Link to post
Share on other sites

My apologies to all in this post as I have not updated it is several months. I am pleased to report that since the initial incident in my original post, the unit has not malfunctioned since.

Thanks to all who replied.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now