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Microwave Making Buzzing Sound [Sound Clip Included]

Discussion in 'Repairing Electronics' started by ParkingLotLust, Aug 21, 2009.

  1. HiTech

    HiTech Well-Known Member

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    And removing a magnetron definitely requires pulling the HV wires to it! How is that not dangerous? Or were you planning to use a 10-foot pole with a hook on it?
     
  2. x_f

    x_f New Member

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    Hi guys,

    I am having the exact same problem as OP explained in this thread, the exact sound comes out of my unit except that it's not only in the beginning of the cycle, it continues and doesn't stop.

    The initial noise happens with all the units I guess, or at least the newer Panasonic ones, but mine has this continued noise which is worrying me.

    The problem started after the service center changed the magnetron, and now I've returned it several times, but they keep telling me nothing's wrong with it.

    Could you guys elaborate on what could be causing the problem? I'm not gonna do it myself of course, since the unit still has warranty. just wanna direct the service guys to the right direction.

    Thanks a bunch.
     
  3. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    I just saw this thread. That noise could very well be the fan bearing. In the top of the microwave cavity there should be a fan. A bad bearing and hitting the sides is what it sounds like to me.

    Magnetrons can buzz very loud when they get past their useful life.


    3 kV is something to worry about and the one hand in your pocket rule applies.

    I've worked on non microwave devices that used power supplies of 100 kV DC, 0.1 and 15 kV, 1.5 Amp DC systems without incident. Then there was this lamp that required 42 A @ 22 V to run and a 40 kV pulse to start.
     
  4. dave

    Dave New Member

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  5. killivolt

    killivolt Well-Known Member

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    The noise in the clip is definitely corona arc somewhere it is concentrated at a point allowing the voltage to go to ground. Sometimes it's grease buildup or some weak spot that it is jumping to and grounding the voltage.

    Once the full wave is achieved, it is dissipating because I don't here it anymore after it's powered up and running at full power. Somewhere in between " Start and full power" it's at the right distance and frequency for the jump. Static discharge could occur during this period of build from 0 to C if the full current is able to move it lowers the Static EM.

    Ultimately pulling the mag and inspecting the area in and around the mount would be a good idea. It's possible if they did that and corrected it they wouldn't get paid by the Company for the new warranty service. Which is common these day's.

    Edit: If it is happing all the time it's probably a good idea to pull the mag out and inspect the mag and all area's around the mount and waveguide.
     
    Last edited: Apr 6, 2011
  6. ritchi64

    ritchi64 New Member

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    I have the same sond as in this post. I use the roler trick to find were it come from. In my case, it come from the inverter board. From the big coil on it. I can't see any arc even in the dark. Is it the magnetron who is begining to be short and hi voltage module have problem to keep up??
     
  7. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    A very good possibility. The magnitron has went south.
     
  8. ritchi64

    ritchi64 New Member

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    Humm the microwave still working but maid a very bad hissing noise at statup!

    I found that R713 is open (replace but blow again). I test C703 with a Ohmmeter and it charge ok but I dont have a capacity meter to test for leakage. I also test CT01, D701/D702, R710/R711, ZD703/ZD704 and DB701 (diode brige). They all looking OK!

    L701 is just a coil. How can it be damage if the microwave still working? what resitance should the Ohmmeter read for that part?

    I also check diode on Q701/Q702 and they read corectly on the Ohmmeter test (G to E).

    I need to find out why R1713 get open immediatly but microwave still working?????
     
  9. apvkt

    apvkt New Member

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    Hi guys,
    I am also facing the same problem that microwave is making the sound very noisy and i take it to the nearest electronic repairing shop and now it is working in a good condition. But before taking it to the shop i have tried with the tips given in this section and finally i took it to the shop.
     
  10. ritchi64

    ritchi64 New Member

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    And apvkt, can you tell us which parts they replace? Maybe you can see this on your invoice?
     

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