Social Buttons
Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Microwave fuse keeps blowing

  1. #1
    Join Date
    May 2012
    Location
    Australia
    Posts
    6

    Default Microwave fuse keeps blowing

    Model Number: nn-8550
    Brand: -major brand-
    Age: More than 10 years

    Have a Panasomnic NN-8550 microwave that, to quote the boss "made a funny noise and stopped working". When I looked at it, there was no power; even the display was dead.

    Pulled the cover off, the fuse was blown, so replaced it. When I plugged it back in the display powered up as per normal and I could set the power level and time as usual. When I pressed start it sounded like normal and seemed ok, but after about 1 sec there were 3 or 4 clunking sounds then it stopped working and went dead. The fuse had blown again.

    I have checked the thermal cutout with my basic multimeter (seems fine) and I took the capacitor with me to the electrical store when I got some more fuses and they tested it for me and said it was within tolerance.

    From what I have read, it doesn't sound like it is the Magnetron and I haven't tested the diode as I am not sure how to.

    I am a novice with microwaves so hope there may be some knowledgeable people out there that may be able to suggest what I should do next to identify the cause.

    thanks

  2. #2
    Join Date
    Oct 2004
    Location
    Ontario, Canada
    Posts
    14,537

    Default

    Hi,

    Quote:
    When I pressed start it sounded like normal and seemed ok, but after about 1 sec there were 3 or 4 clunking sounds then it stopped working and went dead. The fuse had blown again.

    More often than not, a shorted high voltage capacitor.

    Quote:
    I took the capacitor with me to Jaycar when I got some more fuses. They tested it for me and said it was within tolerance.

    Check it again.

    http://www.applianceaid.com/micro4.html

    Quote:
    From what I have read, it doesn't sond like it is the Magnetron and I haven't tested the diode as I am not sure how to.

    Usually the mag or diode won't blow the fuse, they may growl or make a strange noise and stop heating but normally don't blow the fuse.

    Testing...
    http://www.applianceaid.com/component.html

    If needed:


    Capacitor, hv Manufacturer Number A60905500AP

    jeff.
    http://www.applianceaid.com/
    Appliance Repair Aid

  3. #3
    Join Date
    May 2012
    Location
    Australia
    Posts
    6

    Default Capacitor

    Quote:

    Thanks Jeff,

    I have pulled the capacitor out of the microwave again and have tried to test with my digital m/meter. Have followed the instuction on your link, however have a couple of questions.

    1st up, the instructions suggest setting on Rx1. My m/meter has 20M, 200k, 20k, 2000, 200 settings. Internet research says that Rx1 is equivalent to 200. Is that correct?

    2nd, the testing instructions say to "touch the cap terminals ( red lead on left and black lead on right )" Excuse my ignornace, but that is a bit confusing for me. 'doh! As I look at the capacitor as it would be positioned in place in the microwave, there are 2 caps. The left side has 3 terminals and the right hand side has 1. When I connect the red m/meter lead to any 1 of the 3 terminals on the left cap and the black lead to the terminal on the right cap, the reading stays on 1 and doesn't change at all. When I reverse the red and black leads, the reading again stays on 1.

    I am not sure if I am testing the capacitor correctly or whether the capacitor needs to be replaced. BTW, the capacitor is not out of shape or bloated and there are no signs of any oil.


    Hoping someone can help with the next steps. Thanks.

  4. #4
    Join Date
    Oct 2004
    Location
    Ontario, Canada
    Posts
    14,537

    Default

    I have pulled the capacitor out of the microwave again and have tried to test with my digital m/meter
    Needle meter is used...especially for microwave stuff...that's all we use.

    the capacitor is not out of shape or bloated and there are no signs of any oil.
    Normally wouldn't be.

    Internet research says that Rx1 is equivalent to 200. Is that correct?
    Not really.

    When I connect the red m/meter lead to any 1 of the 3 terminals on the left cap and the black lead to the terminal on the right cap, the reading stays on 1 and doesn't change at all. When I reverse the red and black leads, the reading again stays on 1.
    What does your meter say when you put the two meter leads together?

    jeff.
    http://www.applianceaid.com/
    Appliance Repair Aid

  5. #5
    Join Date
    May 2012
    Location
    Australia
    Posts
    6

    Default

    Needle meter is used...especially for microwave stuff...that's all we use.

    thanks Jeff, I only have the digital version.


    Normally wouldn't be.



    Not really.



    What does your meter say when you put the two meter leads together?

    When I put the leads together, it reads 00.4 or 00.5


    thanks Jeff

    Ian

  6. #6
    Join Date
    Jul 2006
    Location
    Murray, Utah, United States
    Posts
    18,789

    Default

    See if this helps:
    Click image for larger version. 

Name:	Cap Test.jpg 
Views:	269 
Size:	51.2 KB 
ID:	5073
    OWNER RICK'S APPLIANCE REPAIR
    APPLIANCE TECHNICIAN FOR 29 YEARS
    REFRIGERATION SPECIALIST
    ONLINE SERV TECH: ApplianceBlog.com
    CERTIFIED TYPE 1; TYPE 2.....REFRIGERATION SERVICE E.S.

  7. #7
    Join Date
    May 2012
    Location
    Australia
    Posts
    6

    Default

    Quote Originally Posted by rickgburton View Post
    See if this helps:
    Click image for larger version. 

Name:	Cap Test.jpg 
Views:	269 
Size:	51.2 KB 
ID:	5073
    Thanks for making it simple for me Rick.

    Set the m/meter to 2000
    Touched tthe probes together and reading was 000
    Then put one probe on A and other on B - reading did not change at all and continued to show 1
    Swapped probes and again reading did not change and continued to show 1

    Do you think that means the capacitor needs replacing?

  8. #8
    Join Date
    Jul 2006
    Location
    Murray, Utah, United States
    Posts
    18,789

    Default

    If the meter didn't change, replace it. Use the link jeff1 gave you.
    OWNER RICK'S APPLIANCE REPAIR
    APPLIANCE TECHNICIAN FOR 29 YEARS
    REFRIGERATION SPECIALIST
    ONLINE SERV TECH: ApplianceBlog.com
    CERTIFIED TYPE 1; TYPE 2.....REFRIGERATION SERVICE E.S.

  9. #9
    Join Date
    Oct 2004
    Location
    Ontario, Canada
    Posts
    14,537

    Default

    What does your meter say when you put the two meter leads together?

    When I put the leads together, it reads 00.4 or 00.5
    Which is wrong, should read 0.

    Then put one probe on A and other on B - reading did not change at all and continued to show 1
    Swapped probes and again reading did not change and continued to show 1
    For what ever reason it is showing open....only thing to do is swap out the capacitor and forget the meter testing.

    jeff.
    http://www.applianceaid.com/
    Appliance Repair Aid

  10. #10
    Join Date
    May 2012
    Location
    Australia
    Posts
    6

    Default

    Quote Originally Posted by rickgburton View Post
    If the meter didn't change, replace it. Use the link jeff1 gave you.

    Thanks for your help Rick and Jeff. Will replace the capacitor and let you know how it goes.

    cheers

Page 1 of 2 12 LastLast

Similar Threads

  1. Why my microwave is blowing internal fuse?
    By adol66 in forum Whirlpool/KitchenAid
    Replies: 6
    Last Post: February 27th, 2012, 08:55 PM
  2. Whirlpool microwave blowing fuse
    By phil25rs in forum Whirlpool/KitchenAid
    Replies: 4
    Last Post: December 31st, 2010, 08:38 PM
  3. Blowing house fuse
    By pucara in forum Whirlpool/KitchenAid/Roper/Estate
    Replies: 7
    Last Post: June 15th, 2010, 11:30 AM
  4. Kenmore Microwave Oven Fuse Keeps Blowing
    By Belligerent in forum Sears Kenmore
    Replies: 2
    Last Post: June 7th, 2005, 12:54 PM
  5. Kenmore Microwave Oven Fuse Keeps Blowing
    By Belligerent in forum Sears Kenmore Reviews
    Replies: 1
    Last Post: December 31st, 1969, 06:00 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
If you feel that you have benefited from this site, and would like to show your appreciation, you can throw a buck or two in the Appliance Blog Tip Jar - Thank you!
Facebook Page: ApplianceBlog Twitter: ApplianceBlog Google+ YouTube: ApplianceBlog