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  • dark lcd display

    From legg@21:1/5 to All on Sat Dec 23 11:39:44 2023
    LCD display is dark.
    All necessary wiggles being delivered to solderable pins.
    Backlight visibly ON.
    Unit runs without indication.

    Is it toast?

    Custom unit for Sharp microwave - only replacement is
    full panel at us$200. Unit retails at us$360.
    'Light Commercial' duty stainless - in marketplace
    since 1999 and still sold.

    Also requires replacement lamp and stirring reflector
    motor.

    RL

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  • From legg@21:1/5 to [email protected] on Sun Dec 24 11:23:11 2023
    On Sun, 24 Dec 2023 05:01:17 -0800 (PST), "Peter W."
    <[email protected]> wrote:

    If you had done your Consumer Reports back in the day, you would have found that Sharp has notoriously frequent display issues. With this in mind, you might contact Sharp for suggestions. They know their reputation, and are counting on the consumers not
    knowing.

    Peter Wieck
    Melrose Park, PA

    Peter,

    I don't buy microwave ovens, I just fix them.

    This model of microwave R21LV has a few variants
    which have been mfred since before Y2K.

    It's service manual illustrates a panel with a
    completely different display on the control board,
    possibly even LED, vs the LCD variety present here.

    I've got nothing but respect for Sharp stuff. My
    pocket calculator from the 90s has been through the
    laundry twice, without permanent damage. It has an
    early type of LCD display.

    I've seen LCDs that have obvious damage/discoloration
    and flakey elements before, but never something that
    was permanently, uniformly dark.

    There's no carbon press strip to degrade, just 15
    solderable in-line pins.

    I would suspect the controller chip, or its ceramic
    resonator, but the chip seems to be performing normally.
    The unit runs.

    RL

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  • From legg@21:1/5 to [email protected] on Sun Dec 24 15:16:13 2023
    On Sun, 24 Dec 2023 09:45:39 -0800 (PST), three_jeeps
    <[email protected]> wrote:

    On Sunday, December 24, 2023 at 11:22:45?AM UTC-5, legg wrote:
    <snip

    I've seen LCDs that have obvious damage/discoloration
    and flakey elements before, but never something that
    was permanently, uniformly dark.

    There's no carbon press strip to degrade, just 15
    solderable in-line pins.

    I would suspect the controller chip, or its ceramic
    resonator, but the chip seems to be performing normally.
    The unit runs.


    "All necessary wiggles being delivered to solderable pins" -
    Not sure what this means so I'll make an inference:
    All the LCD segment lines change state appropriately?
    Checked voltages on all segment pins at the same time
    (with perhaps a 16 line digital analyzer)?
    dream on
    Bias voltage on the LCD correct? If all true then the LCD is dead.
    Does this model have a separate LCD controller chip or does it use a micro with a number of DIO lines?

    Service manual shows 4x9 connections more suited to an LED display
    coming from a 64pin micro through a quad buffer and nine unbuffered
    lines from paralleled ports with 100R series limiters.

    The current rev board is a 56pin QFN package driving the 15 pins of
    the display directly.

    3 of the 15 pins generate quad-state ~ramps between 0 and 5V.
    Pins 1 , 2 and 10.
    The rest just clock (150Hz) between the two mid-state levels, in
    sync with the ~ramping steps.

    This controls segments of 4 digit clock, its middle colon and
    5 symbols for mode of operation, spaced ~ equally below the digits
    and mid-colon.

    I've searched all over for a more accurate service manual, or
    a revision that includes the change to micro and display, but
    this is only reflected in purchasing spares. The old control
    panel assy number is retired to be replaced by . . .

    A custom LCD-only part for the control board assembly isn't a
    likely after-market item. The whole panel is available for $$$.

    This one is from 2012, about half way through the product's history.

    RL

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  • From legg@21:1/5 to legg on Tue Jan 23 09:10:11 2024
    On Sat, 23 Dec 2023 11:39:44 -0500, legg <[email protected]> wrote:

    LCD display is dark.
    All necessary wiggles being delivered to solderable pins.
    Backlight visibly ON.
    Unit runs without indication.

    Is it toast?

    Custom unit for Sharp microwave - only replacement is
    full panel at us$200. Unit retails at us$360.
    'Light Commercial' duty stainless - in marketplace
    since 1999 and still sold.

    Also requires replacement lamp and stirring reflector
    motor.

    RL

    This thing is in working order and programmes.

    It had some gunk penetrating the stiring motor
    couplig shaft area that had carbonized and would cause
    visible arcing, until the polyproplylene components
    were scraped completely clean.

    It's just inconvenient and unsafe to run without
    confirmation of an obvious countdown in the run
    time.

    If I brush my thumb across the display the major
    ' 1 ' and 'ON' segments display, regardless of
    operating state or cooking time. These fade
    gradually.

    RL

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  • From UFO@21:1/5 to All on Mon Feb 26 16:52:44 2024
    Was the product sitting around a long time unused?

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  • From legg@21:1/5 to All on Tue Feb 27 10:39:13 2024
    On Mon, 26 Feb 2024 16:52:44 -0500, "UFO" <[email protected]>
    wrote:

    Was the product sitting around a long time unused?


    It was brought in producing sparks, with a burnt stirring motor,
    burnt lamps. Don't know when the display stopped working.

    In perfect working order, now, but dangerous without feedback
    to end user.

    RL

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