Jump to content



Learn appliance repair at the Samurai Tech Academy.  Learn more.  Earn more.


Parts Search
Site Search

FAQs | Store | Memberships | Repair Videos | Academy | Newsletter | Beer Fund | Contact


Welcome to Appliantology.org, the Web's Premiere Appliance Repair Resource!

The world-famous Samurai Appliance Repair Forums


To get started, click here.


Already a member of the Appliantology Academy? Just sign in with your username and password in the upper right-hand corner of the screen.

 


Photo

KitchenAid Microwave - Loud hum/buzz,no heat - KHMS155LSS

new years eve magnetron

  • Please log in to reply
7 replies to this topic

#1 original_sound

original_sound

    Samanera

  • Grasshoppah
  • Pip
  • 11 posts
  • Flavorite Brew:Schlafly Hefeweizen

Posted 02 January 2012 - 10:31 AM

The latest in a line of New Year's Eve failures at OS's house (a few years back it was a busted heating pipe in the wall), our KitchenAid microwave (KHMS155LSS) failed on the last day of 2011. Very loud buzz/hum when energized - noise cycles on and off if set at less than 100% power - and no heat. Controls, lights, etc. all seem to work. Unfortunately, the replacement model is 3/4" taller and won't work with the custom backsplash above the stove so I am attempting my first microwave diagnosis and repair.

After pulling the beast off the wall and observing all safety precautions, I am about to order a new magnetron based on the symptoms and the following test results. Before I do, I wanted to poll the community to see if magnetron failure may have resulted from something else that I'm missing and to see if magnetron replacement is too tricky for a kohai (or whatever my newbie samurai status is).

Capacitor: fine (though I got no spark/pop when discharging with a screwdriver - is this a clue?)

HV Transformer: fine

Diode - fine. (Was glad I hadn't sold my 12V regulated dc supply at yard sale as the DMM wasn't strong enough and showed it as open before checking voltage while connected to dc supply.)

Magnetron - Short from filaments to chassis/ground

Use the Appliantology Parts Search Box to Find What You Need!
Enter your model number, part number, type of appliance, brand, or even a part description.
365-day return policy on all parts purchased here, even electrical parts that have been installed!

#2 RegUS_PatOff

RegUS_PatOff

    Sensei

  • Academy Instructor
  • PipPipPipPipPip
  • 33,588 posts
  • Location: USA
  • Flavorite Brew:Chief NTSC Black & White

Posted 02 January 2012 - 10:47 AM

... Capacitor: fine (though I got no spark/pop when discharging with a screwdriver - is this a clue?)
... HV Transformer: fine
... Diode - fine. (Was glad I hadn't sold my 12V regulated dc supply at yard sale as the DMM wasn't strong enough
... Magnetron - Short from filaments to chassis/ground

1) Capacitor terminals not shorted ? . . . not shorted to it's case ?
2) Transformer:
Primary winding -- Less than 0.5 ohm (approx.)
Secondary winding -- 100 ohms (approximate)
Filament winding -- 0 ohms
windings to chassis -- Infinite

3) could have tried a 9v battery

4) Magnetron: wires disconnected
Filament terminals - less than 1 OHM
Filament to chassis - infinite
.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#3 original_sound

original_sound

    Samanera

  • Grasshoppah
  • Pip
  • 11 posts
  • Flavorite Brew:Schlafly Hefeweizen

Posted 02 January 2012 - 11:03 AM

Sorry, should have been more specific on my "fine" results

1) Capacitor - across terminals reads XXX ohms then climbs to infinity. Open (infinite) between either terminal and case of capacitor.

2) Transformer - Primary = ~5 ohms, Secondary = ~75 ohms, Filaments = ~2.5 ohms (are these close enough to zero?). Filaments to chassis = infinite.

3) 9V battery would have worked but now I can defend continued presence of 12V supply to wife on next garage inspection

4) Magnetron - terminals continous (less than 1 ohm), terminals to chassis continous (less than one ohm)

#4 RegUS_PatOff

RegUS_PatOff

    Sensei

  • Academy Instructor
  • PipPipPipPipPip
  • 33,588 posts
  • Location: USA
  • Flavorite Brew:Chief NTSC Black & White

Posted 02 January 2012 - 11:15 AM

... now I can defend continued presence of 12V supply to wife on next garage inspection
... Magnetron - terminals continous (less than 1 ohm), terminals to chassis continous (less than one ohm)

1) :whistling: :thumbsup:
2) seems bad
http://www.repaircli...R=154&N=1489083

 

Magnetron-W10245183-01088762.jpg


.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#5 Samurai Appliance Repair Man

Samurai Appliance Repair Man

    Shōgun

  • Master Samurai Tech
  • 29,841 posts
  • Location: USA
  • Flavorite Brew:Sapporo Original Draft Rice Lager

Posted 04 January 2012 - 10:07 AM

If you're getting continuity from the magnetron terminal to ground, the magnetron is fried.

For future reference, I've posted a video on how to troubleshoot a microwave oven HV system ==> How to troubleshoot and diagnose the high voltage system in a microwave oven

#6 original_sound

original_sound

    Samanera

  • Grasshoppah
  • Pip
  • 11 posts
  • Flavorite Brew:Schlafly Hefeweizen

Posted 04 January 2012 - 10:17 PM

Thanks for link. New magnetron is on its way. I will report back once installed and reassembled. What causes magnetron failure of this nature?

#7 RegUS_PatOff

RegUS_PatOff

    Sensei

  • Academy Instructor
  • PipPipPipPipPip
  • 33,588 posts
  • Location: USA
  • Flavorite Brew:Chief NTSC Black & White

Posted 04 January 2012 - 10:22 PM

... What causes magnetron failure of this nature?

could be age or over-heating,
.

one of my video productions: “Easter Seals: Walk With Me”

every day is Down Syndrome Awareness Day
"A Child Is Waiting" . Burt Lancaster . Judy Garland . 1962

RegUS_PatOff > www.youtube.com/watch?v=oPAY2LsKVEw

#8 original_sound

original_sound

    Samanera

  • Grasshoppah
  • Pip
  • 11 posts
  • Flavorite Brew:Schlafly Hefeweizen

Posted 08 January 2012 - 10:59 PM

Magnetron replaced. Microwave reassembled. All knuckles either cut, scraped, or both. Heats water, no buzz, and has been hoisted back up onto the wall. If it breaks again, we're moving! Thank you all for guidance/confirmation.





Also tagged with one or more of these keywords: new years eve, magnetron

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users


FAQs | Store | Memberships | Repair Videos | Academy | Newsletter | Beer Fund | Contact


Use the Appliantology Parts Finder to Get What You Need!
Enter a model number, part number, type of appliance, brand, or even a part description.
365-day return policy on all parts purchased here, even electrical parts that have been installed!

Your Sometimes-Lucid Host:
Samurai Appliance Repair Man
"If I can't help you fix your appliance and make you 100% satisfied, I will come to your home and slice open my belly,
spilling my steaming entrails onto your floor."


The Appliance Guru | Master Samurai Tech

Real Time Analytics