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Thread: TRS80 Model 4 Keyboard Repair (Membrane Keyboard)

  1. #1

    Default TRS80 Model 4 Keyboard Repair (Membrane Keyboard)

    I found a 2015 thread on this but it's not clear how having dismembered the keyboard anyone got it back together.

    It looks like something flexed the keyboard a lot, broke a load of the little pins and let a few springs out. I can get it apart easily enough by taking the tops off the remaining pins, what I don't see is how to get it back together again. This is of course assuming the membrane hasn't died.

    Does anyone do replacement membranes if so - as they do with a load of the other machines ?

    Alternatively are the proper keyboards a direct swap if I can find someone selling one ?

    Alan

  2. #2
    Join Date
    Mar 2016
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    Pikesville, Maryland
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    Can you post a photo of the keyboard
    If the keyboard is a "membrane" (by my definitions) then trash it ... once taken apart you cannot put it back together again
    If the keyboard is an alps keyboard (you can tell by looking at the bottom of the keyboard - you can see all the keys soldered to the board) - then it can be repaired
    I do have keyboards for the Model 4

    But first post a picture

  3. #3

    Default Keyboard

    Quote Originally Posted by Jay Newirth View Post
    Can you post a photo of the keyboard
    If the keyboard is a "membrane" (by my definitions) then trash it ... once taken apart you cannot put it back together again
    If the keyboard is an alps keyboard (you can tell by looking at the bottom of the keyboard - you can see all the keys soldered to the board) - then it can be repaired
    I do have keyboards for the Model 4

    But first post a picture
    Picture attached.

    It's not an ALPS alas.

    Alan
    Attached Images Attached Images

  4. #4
    Join Date
    Mar 2016
    Location
    Pikesville, Maryland
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    From the photo you are shit out of luck ..... the membrane keyboards are impossible to repair .... Those "pins" are what hold everything together ---- and when you "break" them off --- guess what ------ case will not go back together

    Best to replace with an ALPS keyboard

    Contact me at JAYNEWIRTH@VERIZON.NET to discuss further if you wish

  5. #5

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    I've made some progress. Now I know there isn't a nice way to do it I've taken it apart, I've put all the springs back and fixed the springs that needed attention. The membrane itself appears good so I'm now working on reassembling it.

    I've got some thin but stiff aluminium angle the right size to go over the sides of the plastic and support the rest, and very small screws. Measuring and poking suggests it will all still fit although I should have used steel because now I'm going to have to tap the aluminium to take another pair of earthing screws to properly earth them as well as backplate. It certainly feels rigid enough

    Just need to find time to drill all the screw holes.

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