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Broken Remote for Cable Box

Discussion in 'Electronic Repair' started by [email protected], Aug 5, 2008.

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  1. Guest

    I've a broken remote for a cable TV box. It's been replaced,
    so the repair is non-critical -- just-for-fun!

    Anyway, 3-buttons failed simultaneously. They are horizontally

    After disassembling and inspecting -- there seem to be no
    broken PCB traces and the PCB contact portion of the keyboard
    looks OK.

    The key contacts are a thickish, black material applied to a
    single-sided PCB in an open matrix pattern.

    After some simple tests, verifying the "rubber" buttons for the
    failed keys work at other PCB pads and that the "bad" PCB pads
    weren't activated by "good" rubber buttons, there seem to be 2
    possible (likely) failures:

    1. A key-matrix leg of the control electronics has "died".
    2. The "paint-trace" contact material has disconnected from
    its PCB trace.

    If the chip's died or a surface-mount element's fried, it's
    probably not fixable. (Not by me anyway.)

    So -- any suggestions on methods to re-attach the 3-key leg?

    Or -- any other failure scenarios?
  2. jakdedert

    jakdedert Guest

    As a first step, try cleaning the affected pads. That may produce a
    fix. If not, short the pads with sharp probes to see if those functions
    work. Otherwise, trace back from the keypads, and short the traces
    which seem to correspond to them...further back down the line.

    If none of the above produces a response, you might have a component

    BTW, a digital camera makes a good IR detector. Just point it at the
    remote when in operation. The IR LED will be plainly visible....

  3. lurk

    lurk Guest

    also check the oscillator by tuning an AM radio on the low end of the
    band...say 500 KCS and push any button on the should hear
    a buzz
  4. Guest

    I did dry-wipe them with cotten. They look good -- no dust or gunk.
    I should have been clearer -- the other 20-30 keys all work. Only the
    row of 3 doesn't work.

  5. Guest

    I should have explained better in the original post: only the
    row of 3 keys stopped working, the other 30 (or so) are all OK.

  6. jakdedert

    jakdedert Guest

    No, I got that. Perhaps your remote has visible LED to indicate button
    pushes, but many don't. I suggested it as a visual confirmation of
    control input.

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