Question about Panasonic NN-H275 Microwave Oven

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Fuse blows on microwave switch on

Every time when microwave switched on the fuse blows.
Started yesterday just during normal operation.

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  • William Miller
    William Miller May 11, 2010

    If it went dead almost
    immediately after pressing the Start pad, that's usually a shorted
    high-voltage capacitor.

    If it went dead
    several seconds after pressing the Start pad, that's usually a
    high-voltage transformer.

    it goes dead or blows the breaker (or GFI) when you plug it in or open
    or close
    the door, then there's a problem with a door switch or door switch
    mount. Please reply back with your brand and model number so we can help you.



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Hi, I have an Elitech combination microwave which is kept in a cupboard (little air flow), the other day i used it to cook 4 jacket potatoes so it was running for about 25 minutes, near the end of the cooking i noticed a slight burning smell coming from the cupboard and then noticed the potatoes was no longer cooking but everything else looked as it was working ok. On inspection the internal fuse on the HV side had blown, Fuse 0.7A 5kV, i bought another fuse at £5.28 and put it in the unit, i put a cup of water into the microwave and set it running, there was the noise that the microwave normally makes but maybe slightly louder for about 10 seconds and again the fuse blew, can anyone please help to narrow down the possible problem, i understand it could be the HV transformer, the magnetron, the capacitor or the discharge diode. Thanks, Peter.

Posted on Mar 07, 2010

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One of three things shorted could cause this: H.V. diode,capacitor,or the magnetron tube, take screw driver and short terminals on capacitor before touching anything inside the case, then chk resistance on capacitor should show infinite after needle settles, diode should show hi resistance one way and a lower resistance in the other direction(use the RX100 scale not the RX1) on both parts diode should not show very low resistance or it could be leaking,mag is a different story,it can be chk'd but in a different way

Posted on Jul 27, 2009


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You can get more information about adjuting the interlock switch from this link

sections 7-11 thru 7-12 discuss the door interlock adjustment that will cause the 20A fuse to blow if it isn't set up right. I hope this helps you...

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