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Usual failure modes of magnetrons?

Discussion in 'Electronic Repair' started by [email protected], Jan 8, 2012.

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  1. Guest

    Greetings All,
    I have a Sharp brand "Half Pint" 400 watt microwave oven my wife and I
    bought new in 1986. The thing still works like new. I use it now in
    my shop because we have bought more powerful microwave ovens over the
    years to use in our house. We have bought more than one because the
    magnetrons in the others failed. At least I think the magnetrons
    failed because there was still really high voltage going to the
    magnetrons and the other oven functions worked (timer, digital
    display, etc.). So I was wondering why my old Sharp Half Pint oven
    still works and how magnetrons failed.
  2. Paul Drahn

    Paul Drahn Guest

    Magnetrons are still vacuum tubes with heaters in them. They are
    probably made in China and quality control is letting crap out the door.

  3. mike

    mike Guest

    How did you measure the "really high voltage going to the magnetron"???
  4. Sorry, you are wrong. CE aka China Engineering aka Crap Enforcement
    doesn`t let quality in, so there is no quality production :]

    Saludos Wolfgang
  5. Paul Drahn

    Paul Drahn Guest

    Yes, that is true, in some cases. On the other hand, I buy GPS receiver
    assemblies, complete with antenna, by the thousands from China and have
    never had a bad one.

  6. Good to hear, that not every product is controlled by Crap Enforcement

    Saludos Wolfgang
  7. Phil Allison

    Phil Allison Guest

    "Paul Drahn"

    ** Magnetrons for Sharp microwave ovens made in China back in 1986 ????

    That was the era when Japan and Taiwan were dominant.

    ..... Phil
  8. Phil Allison

    Phil Allison Guest

    "Jim Yanik"

    ** Must be some cases of loss of vacuum.

    Affects lots of valves, big and small.

    ..... Phil
  9. Winston

    Winston Guest

    I've dissected a few microwave ovens to salvage
    transformers and for fun.

    I've found cracked magnets on a few magnetrons.

    I don't know if a cracked magnet would cause the
    failure of a magnetron, if that was the root cause
    of the failures or if some other failure caused
    the magnets to crack.

  10. Winston

    Winston Guest


    I wonder if a cracked magnet could cause low microwave

    Sounds like a chicken and egg problem.
    Excessive power dissipation in the magnetron might
    cause a magnet to crack. (Line transient perhaps?)
    The cracked magnet would push the magnetron
    away from cutoff, forcing it to dissipate more
    power which heats the magnets, etc.

  11. josephkk

    josephkk Guest

    The new planned obsolescence.
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