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Temperature probe - LCD display missing segments

Discussion in 'Troubleshooting and Repair' started by Martfoxy, Jan 25, 2021.

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  1. Martfoxy

    Martfoxy

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    Apr 25, 2013
    I have a temperature probe where the LCD display is missing parts of the display. Also happening on a DECT phone I have as well.
    Is there any way of fixing problems with LCD displays when this happen?

    lcd.jpg

    Thank you
     
  2. Martaine2005

    Martaine2005

    3,421
    928
    May 12, 2015
    Not if it’s the LCD.
    But bad connections are common.
    Ribbon cables and/or solder joints can be checked.
    Sometimes squeezing or twisting (carefully) the device can confirm a bad connection.

    Martin
     
  3. kenny256

    kenny256

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    Jan 4, 2020
    Use a pencil eraser to clean the contact surface on the board, and gently clean the glass contacts of the screen with alcohol on a cotton swab. Be careful not to damage the carbon-foam "sponge" between the board and glass. If that doesn't get it working then the foam will likely need to be replaced.
     
    Martaine2005 likes this.
  4. 73's de Edd

    73's de Edd

    3,086
    1,302
    Aug 21, 2015
    Sir Martfoxy . . . ..


    Have you got that torn down, for a photo, at least to the state that you see here . . . as further pulling the two phillips screws . . . . releasing the wires out of the melted / fused plastic will be needed, then, maybe the frontal display portion, to be worked on, can be fully observed.
    Then I can see if my timely procedure used with Zebra strips can be initiated.

    Observers note . . . . in the far highest bleachers of the peanut gallery . . . . . . . that is NOT being a ribbon cable at the very top . . . 'tis the springy-dingy antenna for the wi-Fi aspects of the unit.

    VIZ . . . . .
    upload_2021-1-26_0-3-38.png
     
    Last edited: Jan 26, 2021
    Martaine2005 likes this.
  5. Martfoxy

    Martfoxy

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    Apr 25, 2013
    I have taken the probe apart and it has spiders and insects inside!! It is used outside. I have attached a photo of the inside.

    [​IMG]

    Thank you!!
     

    Attached Files:

    Last edited by a moderator: Jan 31, 2021
  6. kenny256

    kenny256

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    Jan 4, 2020
    How is the LCD screen connected to the board--is there a "zebra" striped foam piece underneath the top edge of the glass where the electrical contacts are made?

    That's when they say your electronics has "bugs". i had an outdoor electric car charging station shutdown because a baby praying mantis got inside and shorted across a high voltage junction...
     
  7. Martfoxy

    Martfoxy

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    Apr 25, 2013
    Yes there was a flying bug in there as well!! Yes there is a zebra striped foam under the display.

    A baby praying mantis - aren't they dangerous!
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    11,446
    2,628
    Nov 17, 2011
    That one no longer.
     
    Martaine2005 likes this.
  9. kenny256

    kenny256

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    Jan 4, 2020
    Then follow the instructions of post #3, or wait until the good nasa Mr. Edd gives his instructions for cleaning the zebra strips.
     
    Last edited by a moderator: Jan 31, 2021
  10. 73's de Edd

    73's de Edd

    3,086
    1,302
    Aug 21, 2015
    Sir Martyfoxy . . . . .
    Hmmmmmmmm . . .that's being a somewhat older version.
    I see the potential, of up to 6, of my marked in RED X MARKED holes and their installed captive SM screw as holding this PCB against the front cases face bezel for the LCD display.
    ( Probably with the larger 4 ones the very closest to the display, as being the critical LCD clamping /pressure ones. )
    Take note of the twentyish rectangular contact areas ### that need to have contact interfacing between the PCB propers typically gold flashed contacts on the identical superimoposed contact positions of the RED outlined portion of the YELLOW outlined LCD Displays glass panel.
    They are being dependent upon spaced out . . . and alternatively insulated from each other . . . small strip clusters of conductive carbon fibers. Nicknamed Zebra strips, as the alternative blacks strips are the end to end conductive fibers and the white / or / insulator / products colors are being the insulative separators.
    That is shown in better and even more exacting detail in the second illustration.


    YOU MAKEE FOR ME . . .TESTIE - TESTIE TIME !

    You now power up that already opened up / accesssible unit and observe its inactive segments on the LCD display.
    If you will line up 4 equally spaced out fingers ( of your hand ) across the total width *** of that RED marked in rectangle on the LCD display, now, I hope that with incrementing pressure downwards upon it, that you will then see the inactive ones then popping on and coming to life.
    If so, we can fix, its deeper root problem..
    It is strange, that I am seeing all of the rectangular contacts segments ###, but can't definitively see the interconnective ZEBRA strip due to your top camera angle of its shot.
    Could you see if it is being visible from the left side and then take a side camera shot from the marked in YELLOW arrow direction ?
    If you come out with all segments workable, I will pass on my own self developed, ever unwinding, procedure of 40 yrs of enhancements of your present situation.

    Just now caught your . . . . .Yes there is a zebra striped foam under the display . . . . at this post time.

    The two relevant visual references are being included . . . . here . . . .
    https://i.ibb.co/DzkJJZh/433-Mhz-remote-weather-station-PCB.png[​IMG]

    upload_2021-1-29_6-4-8.png



    73's de Edd . . . . .


    A flying saucer is the result of a nudist having spilt his*HOT* coffee in his lap.
     
    Last edited: Jan 29, 2021
    Martaine2005 likes this.
  11. Martfoxy

    Martfoxy

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    Apr 25, 2013
    I have noticed a couple of the pillars the screws were screwed in have broken so might not have been enough pressure to hold LCD connection. I am gluing and will try again tomorrow.
     
  12. Martfoxy

    Martfoxy

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    Apr 25, 2013
    Also we have a couple of these BT phones where the LCD display looses bits. Its different with a ribbon cable on these. Is there anything I can do or are these unrepairable?

    [​IMG]
     

    Attached Files:

    Last edited by a moderator: Jan 31, 2021
  13. 73's de Edd

    73's de Edd

    3,086
    1,302
    Aug 21, 2015
    On the sytrene plastic cracked / fractured mounting pillars.

    Find one that is still good and place one of the proper mounting screws just inside the hole and then place your Phillips screwdriver atop it into its cross slots.
    Put just a trace of downwards pressure on the end of the screwdriver while you are starting a CCW rotation to the screwdriver for about a full turn.
    If you had just enough downward pressure on the screwdriver, you should have heard two weak clicks as the thread patterns of the sheet metal screw aligned up with the INITIAL thread chases made into that pillar back on day one of the initial assembly of the unit.
    If not hearing the clicks exert just a skosh of extra pressure. . . .try again.

    With your now further gained experience of that effect, you should be able to aurally lock in on the timing of the click and stop at that instant and then slowly start rotation in a normal CW direction. That should then result in the threads going into the original channels created back on day one . . . . with a smooth rotation on up to well past a half turn in a trial testing / confirmation.
    OTHERWISE . . . .
    Just try just randomly dropping a screw into a pillars internal hole and immediately cranking down on it in the normal CW rotation, and then fully expect the outward expansion of a NEW threading to be walowing out / splitting / or / shattering the old, dried out and brittle pillar.

    I am gluing and will try again tomorrow.

    Using Superglue or Epoxy ?
    And of course, there is the superlative ultimate fix . . . . . .
    By going to a FULL service hardware store and getting yourself a length of round brass or aluminininnyumyum tubing from the K&S Metals sections stock.
    It needs to be just minutely larger than the pillar diameter, then cut to proper length and use water like epoxy for an install.
    The only way that the pillar will then fail is a forcefull (sabotage) snapoff back at the origin of the pillar molding into the case proper or a wallowing out of the plastic internals of the now externally metal encased / reinforced pillar.


    Thaaaaaaassit . . . . .



    73's de Edd . . . . .
     
    Last edited: Jan 30, 2021
  14. kenny256

    kenny256

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    Jan 4, 2020
    That's great advice Mr. Edd. i've been doing the initial CCW to find the chase point for years to avoid blowouts but have never seen or heard it explained before--you have done an excellente job.
     
    Last edited by a moderator: Jan 31, 2021
  15. Martfoxy

    Martfoxy

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    Apr 25, 2013
    Very good advice thanks very much.
    Got it screwed back together. Will try your idea of round tubing over the pillars - I would like to fix it properly.
    I used shoe goo (rubbery very strong glue). But I will redo it with tubing and epoxy be nice to get a decent fixing.
    Had some of the wires coming off as very thin and corroded but have soldered back on and it still works.

    Thank you
     
  16. 73's de Edd

    73's de Edd

    3,086
    1,302
    Aug 21, 2015
    and it still works.
    And would that be to the original state of disrepair, with digits . . or . . . . segments inoperative, or NOW . . .do all digits fully display ?
    Pee Ess . . . . I gots a PM . . . . sent to you . . . awaiting for your answering.


     
  17. Martfoxy

    Martfoxy

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    Apr 25, 2013
    Yes still some segments inoperative - did you want a photo in the direction you suggested before first?
     
  18. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Yep
     
  19. Martfoxy

    Martfoxy

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    Apr 25, 2013
    Not sure you can see much on this photo.
     

    Attached Files:

  20. Martfoxy

    Martfoxy

    54
    0
    Apr 25, 2013
    Tried putting pressure on the LCD zebra area but not having much luck getting the missing segments back.
     
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