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Sharp microwave display failure

Discussion in 'Electronic Repair' started by Techguy, Oct 30, 2006.

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  1. Techguy

    Techguy Guest

    Some of the LCD elements (small squares) on the display are failing to
    light. If I push on the end of the ribbon cable where it connects to the
    edge of the display driver PC board, the problem elements will start
    working until I remove the pressure. This leads me to think that the
    ribbon cable's connection pads are failing. Is there any way to repair
    the PC connection pads for each conductor of the ribbon cable on the
    edge of the board? There isn't any hardware connector for the ribbon
    cable on the board. It connects directly to the pads on the edge.

    BTW- This is the second time the display has failed in the same way. I
    replaced the entire display assembly (LCD and driver board) about two
    years ago. Cost about $90. The replacement worked fine until recently.
    Since the home is not occupied in the winter, the heat is turned off.
    The temperature can get down to well below freezing for days or weeks.
    Could this be why the display has failed twice?

    Thanks
     
  2. Wouldn't a whole new oven cost that?
     
  3. Guest

    This reaffirms my belief that modern Sharp microwaves are crap.
     
  4. Meat Plow

    Meat Plow Guest

    I've done it before but without a picture it's hard to tell what you have.
    I doubt it. Lots of new stock is stored in non climate controlled areas in
    the winter.

    I would buy a new oven if you can't fix this one for a lot less than 90
    bux.
     
  5. Jeff, WB8NHV

    Jeff, WB8NHV Guest

    Not necessarily. I have a Sharp Carousel microwave which I bought
    new almost seven years ago. Still works almost as well as it did the
    day I bought it. I say "almost" because every once in a while the
    machine will refuse to start when the door is closed--it takes a couple
    of openings and closings to get it to work. This is intermittent; most
    of the time the microwave works exactly as it should. Very difficult to
    predict just when it will happen. I think the door switches are either
    very dirty from grease, etc. or simply wearing out after seven years of
    daily use.

    As to your belief that all recent-vintage Sharp microwave ovens are
    "crap", that's your opinion and you are entitled to it. However, I
    don't really think there are many microwaves out there that will last
    years or decades as the old Amana Radaranges, Tappans, etc. used to. (I
    recently read in another discussion forum of an Amana Radarange that
    was still going strong after almost three decades.) Today's
    microwaves, like just about everything else these days, are made
    offshore, which often means lower quality, which in turn means the
    device will not last as long as American-made appliances did. The very
    low prices of new microwaves these days (I've seen them priced as low
    as $30) means it is not cost-effective to repair them when they go bad,
    especially from a major component failure such as the magnetron.
    Remember that any repair station nowadays will charge a minimum fee
    just to look at a piece of equipment; this will be in addition to taxes
    and the cost of any repairs done to the unit. If you paid only $30-$40
    or so for the microwave and it will cost $90 to have it repaired, your
    best bet is to junk the old unit and buy a brand new one; that or
    simply put up with the defective display, as long as the oven works
    well otherwise.

    Low or downright cold temperatures in and of themselves will not
    ordinarily kill an electronic device, but they won't do the device any
    good, either. I would find a way to keep the heat on to maintain a
    temperature of, say, 68 or 70 degrees F. during the winter in the home
    where the defective microwave is located, or make arrangements to have
    someone live in the home during the winter months so that keeping the
    furnace going will be justified. There are likely other devices such as
    radios, televisions and the like in the dwelling that are taking a
    beating from the lack of heat as well.



    Kind regards,

    Jeff Strieble, WB8NHV (email addy not shown to deter spammers)
    Fairport Harbor, Ohio USA
     
  6. Techguy

    Techguy Guest

    The microwave is built into the cabinets above the stove with an exhaust
    fan. A new one would cost at least $200 along with the hassle of
    removing and installing.

    This ribbon cable is a thin plastic strip about 50-mm wide. It has two
    layers. One layer has the conductive traces imprinted on the inside
    surface. The other serves as a backing layer to protect the traces. The
    back surface of the ribbon cable is peeled away from the conductor layer
    at the end of the cable. The backing is glued to the reverse side of the
    PC board edge to relieve the strain on the conductor connections. I
    can't tell for sure if the ribbon conductors are soldered to the board.
    The protective backing makes me think the conductor traces are self
    adhesive and the backing has to be removed to attach the conductors to
    their corresponding pads on the PC board.

    Does this sound like the kind of ribbon cable you repaired? Could you
    give me a general idea of what you did to repair yours? I can supply a
    picture if necessary.

    Thanks
     
  7. Do a search for zebra connector for more info.
     
  8. Techguy

    Techguy Guest

    I'm familiar with a foam Zebra strip which is several millimeters thick.
    I've never seen that material used to make a ribbon cable. The ribbon
    cable in question is made with two thin layers of plastic film
    sandwiched together. One inner surface has the conductor traces and the
    other is the protective layer over the conductors. The cable is less
    than 1-mm thick.
     
  9. IME rubber zebra strips - haven't seen foam. However it is a fact that some
    processes are not doable in the field and it is possible that this is one.
     
  10. Mike

    Mike Guest

    this is why I stick with the old vacuum flourescent microwaves. work great.
    :)
     
  11. Yep. I like my all tube VCR and Ipod also!
     
  12. Techguy

    Techguy Guest

  13. Love it!


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