Microwave diode bad?

Discussion in 'Electronic Repair' started by Andrew Rossmann, Aug 28, 2011.

  1. I have an older, 1998 GE Microwave oven. By the LG parts inside,
    probably just a rebadged LG. Lately, it's tended to 'thunk' when the
    magnetron turns on. A few times, it started rapidly cycling. Once, I
    didn't stop it in time and it blew it's 20A fuse. Another time, just
    starting normally, it tripped a circuit breaker.

    I opened it up and checked. So far, the only obvious thing I can see is
    that the large diode between the transformer and ground may be open. I
    get infinite resistance in both directions. I assume there is nothing
    special about testing these types of diodes?

    It's an HVR-1X diode. This appears, based on some Googling, to be very
    common, and the HVR-1X3 seems to be a common replacement.

    Do the symptoms I describe seem to go with the way the microwave is
    acting? I'm not certain just what the true function of the diode is in
    this case (I know how a diode itself works). There is also what looks
    like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.

    Do you think it's worth trying to replace it? I did buy a replacement
    microwave, but regret it. It's basically the same, but has some issues I
    don't like (display too far back from front, so you have to squat down
    to see it while typing on the panel. Fan goes REAL fast when magnetron
    off, then seems to nearly die when it's on.)

    --
    If there is a no_junk in my address, please REMOVE it before replying!
    All junk mail senders will be prosecuted to the fullest extent of the
    law!!
    http://home.comcast.net/~andyross
     
    Andrew Rossmann, Aug 28, 2011
    #1
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  2. In article <>,
    says...
    > >It's an HVR-1X diode. This appears, based on some Googling, to be

    very
    > >common, and the HVR-1X3 seems to be a common replacement.

    >
    > That diode is spec'ed at having a large forward voltage drop (10-14
    > volts). I regular ohm meter will not provide a voltage that high and
    > will show open.


    Is there a simple setup I can create to test it?

    --
    If there is a no_junk in my address, please REMOVE it before replying!
    All junk mail senders will be prosecuted to the fullest extent of the
    law!!
    http://home.comcast.net/~andyross
     
    Andrew Rossmann, Aug 28, 2011
    #2
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  3. In article <-september.org>,
    andysnewsreply@no_junk.comcast.net says...
    >
    > In article <>,
    > says...
    > > >It's an HVR-1X diode. This appears, based on some Googling, to be

    > very
    > > >common, and the HVR-1X3 seems to be a common replacement.

    > >
    > > That diode is spec'ed at having a large forward voltage drop (10-14
    > > volts). I regular ohm meter will not provide a voltage that high and
    > > will show open.

    >
    > Is there a simple setup I can create to test it?


    I guess I'll answer my own question! I used a 12V UPS battery I had
    (12.89V measured) and checked if I could measure voltage through it. The
    diode does work and measured about 9.5V.

    Any other ideas on what could cause the power surge when the magnetron
    is activated? The waveguide is clean. I removed the mica cover over it,
    and there was nothing inside.

    --
    If there is a no_junk in my address, please REMOVE it before replying!
    All junk mail senders will be prosecuted to the fullest extent of the
    law!!
    http://home.comcast.net/~andyross
     
    Andrew Rossmann, Aug 28, 2011
    #3
  4. Andrew Rossmann

    Spamm Trappe Guest

    Re: Microwave oven diode bad?

    On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:
    >
    > There are not regular diodes. There are a stack of diodes, and have
    > a higher forward voltage drop.


    Since there obviously lacking, their ought to be continuing education
    classes where illiterates can improve they're language skills.
     
    Spamm Trappe, Aug 28, 2011
    #4
  5. Andrew Rossmann

    Jamie Guest

    Andrew Rossmann wrote:

    > I have an older, 1998 GE Microwave oven. By the LG parts inside,
    > probably just a rebadged LG. Lately, it's tended to 'thunk' when the
    > magnetron turns on. A few times, it started rapidly cycling. Once, I
    > didn't stop it in time and it blew it's 20A fuse. Another time, just
    > starting normally, it tripped a circuit breaker.
    >
    > I opened it up and checked. So far, the only obvious thing I can see is
    > that the large diode between the transformer and ground may be open. I
    > get infinite resistance in both directions. I assume there is nothing
    > special about testing these types of diodes?
    >
    > It's an HVR-1X diode. This appears, based on some Googling, to be very
    > common, and the HVR-1X3 seems to be a common replacement.
    >
    > Do the symptoms I describe seem to go with the way the microwave is
    > acting? I'm not certain just what the true function of the diode is in
    > this case (I know how a diode itself works). There is also what looks
    > like a starter cap. It's rated at 1uF, and my meter says 1.15uF or so.
    >
    > Do you think it's worth trying to replace it? I did buy a replacement
    > microwave, but regret it. It's basically the same, but has some issues I
    > don't like (display too far back from front, so you have to squat down
    > to see it while typing on the panel. Fan goes REAL fast when magnetron
    > off, then seems to nearly die when it's on.)
    >

    That diode you speak of can not be tested in a conventional DIODE test
    in a DMM. It has several single diodes in series to up the over all
    operating voltage, each one ~ 0.6 volt drop. Most basic diode modes in
    DMM will only cover up to 2/3 in series. Long story short, you need
    more voltage to be applied to the diode for a test. Some of us have
    HV variable supplies, some crude, some elegant, like mine :)

    A Varistate, HV transformer and HV probe works well to test these.

    Jugging from your description, my guess would be a bad magnetron, one
    that has an intermitting short.


    Jamie
     
    Jamie, Aug 28, 2011
    #5
  6. Andrew Rossmann

    Jamie Guest

    Andrew Rossmann wrote:

    > In article <-september.org>,
    > andysnewsreply@no_junk.comcast.net says...
    >
    >>In article <>,
    >> says...
    >>
    >>>>It's an HVR-1X diode. This appears, based on some Googling, to be

    >>
    >>very
    >>
    >>>>common, and the HVR-1X3 seems to be a common replacement.
    >>>
    >>>That diode is spec'ed at having a large forward voltage drop (10-14
    >>>volts). I regular ohm meter will not provide a voltage that high and
    >>>will show open.

    >>
    >>Is there a simple setup I can create to test it?

    >
    >
    > I guess I'll answer my own question! I used a 12V UPS battery I had
    > (12.89V measured) and checked if I could measure voltage through it. The
    > diode does work and measured about 9.5V.
    >
    > Any other ideas on what could cause the power surge when the magnetron
    > is activated? The waveguide is clean. I removed the mica cover over it,
    > and there was nothing inside.
    >

    Doing a forward test on a HV diode does not mean it's good, you still
    could have a break down problem with HV entered.

    Jamie
     
    Jamie, Aug 28, 2011
    #6
  7. Andrew Rossmann

    Jamie Guest

    Re: Microwave oven diode bad?

    Spamm Trappe wrote:

    > On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:
    >
    >> There are not regular diodes. There are a stack of diodes, and have
    >>a higher forward voltage drop.

    >
    >
    > Since there obviously lacking, their ought to be continuing education
    > classes where illiterates can improve they're language skills.


    Discussing such matters with MT is futile. Give it enough time, you'll
    also be editing your list.

    Jamie.
     
    Jamie, Aug 28, 2011
    #7
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