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Electronics Broken Keyboard - Help!

Discussion in 'Modding' started by Mojo, 10 Jan 2023.

  1. Mojo

    Mojo Multimodder

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    Hello folks,
    I have an old Anidees Prismatic bluetooth keyboard which i am trying to fix.
    I can see some damage in this area - Circled. I haven't yet checked but suspect that diode is probably gone too.

    Does anyone have any idea where i might need to solder from and to in order to make the circuit?

    Anyone local to Basingstoke who fancies a bash doing the soldering?

    [​IMG]
     
  2. Midlight

    Midlight Minimodder

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    I'd maybe look at replacing the resistor in the location that looks like it says RB4. Possibly need to reflow the solder joint just below the diode there. Its a little difficult to make out but I can't see anywhere the damaged track goes to so, you may not need to do anything about that.
    I would put in the caveat here that I am no expert in these things, best I've done is a repair on a Bop It that had some corroded tracks.
     
  3. Mojo

    Mojo Multimodder

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    [​IMG]
    [​IMG]
    [​IMG]~

    Heres some better pics :)

    That little diode and resistor might be beyond my skills :)
     
  4. Xlog

    Xlog Minimodder

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    It looks like trace between cathode of ND17 and through-hole pin on the left is missing, you'll need to bridge that. If diode itself is fine you cant test with multimeter, though because corrosion is close by, it might not be solder-able anymore. Its most likely 1N4148 or similar.
    Next will need to remove the remains of RB4, clean up and asses the damage, might need to also swap out QX4. Good thing is that circuit is duplicated elsewhere, so you can remove those components and measure (if you cant get values from markings on the parts).
     
  5. Mojo

    Mojo Multimodder

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    Xlog, I can solder and i reckon i could probably manage it..

    Could you do me a favour and doodle where would you solder wire from and to? :naughty:

    Ordered a new resister for RB4
    What is QX4? It's got 3 pins?
     
  6. Xlog

    Xlog Minimodder

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    upload_2023-1-11_13-48-57.png

    Red is a prob missing trace.
    Black are traces I would also check, its very hard to tell from photos, but it seems there is at least surface damage (scrape off soldermask and check continuity with multimeter)
    Blue is a guess that its how should be connected, but its very hard to tell, check after removing remains of RB4 and you can also double check on another circuit.
    QX4 is a transistor, does it have any markings on it? Best guess its a P-MOS of some kind, there should be VDD (5 or 3,3V) on the left pin.
     
  7. Mojo

    Mojo Multimodder

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    So we have had a bit of success - so i cleaned the board some more and RB4 fell off :grin:

    Checked to see if the traces were touching and they are.. decided - lost nothing at this point so shorted RB4 just to see if it impacted and all of the led's came on as they should... so just that to replace :D

    Thank you ever so much Xlog for your help!
     
  8. Cheapskate

    Cheapskate Insane? or just stupid?

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    Don't clean with a wire brush. :lol:
     

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