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Thread: Sol20 keyboard issue

  1. #11
    Join Date
    Sep 2006
    Location
    Silicon Valley
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    1,420

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    Quote Originally Posted by falter View Post
    When I last bought pads from another seller they were a lighter density green foam with mylar and they work awesome.
    Those were closer to the material KT originally used. You really want to use low-density polyethane foam instead of the polyurethane so they won't crumble over time, but
    it is difficult to find. The main difference will be key travel and force required to actuate a key. I've made hundreds of them, an example is on the left here:
    pad.JPG
    Higher density, but the same thickness as the originals.

    see:
    https://groups.google.com/forum/#!to...st/ki86xMT7gww
    "Making perfect Keytronic replacement keypads"
    Last edited by Al Kossow; June 22nd, 2018 at 07:51 AM.

  2. #12
    Join Date
    Jan 2011
    Location
    Vancouver, BC
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    I've done a ton of checking around and still not sure what's going on.

    I've removed and cleaned every IC on the thing, with no change in behavior. I've tried swapping ICs with known good, and testing the existing in other machines. No problem. I've checked every IC pin connection to the PCB (from top of chip leg to where the socket leg is soldered in). No problem.

    One strange aspect is no matter how long you run the Sol for after the keyboard starts working (usually about 5-10 minutes), if you shut it off even for 10 seconds and then power back on.. you're back to square one. I would have thought if it was a cold solder problem or a component that only makes proper contact after being heated up, that it'd still work after a quick power off and restart, since the heat would not dissipate that quickly.

    I note that certain functions like keyboard reset work no problem right off the bat.

    I guess I'll check out the caps now (though I'm not great at that) and replace em.. see if that helps.

  3. #13

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    Do you have a scope or logic analyzer you can use to check if the keyboard provides data immediately from power up? With even just a logic probe you can verify the keyboard's behavior as far as its data strobing and special signals at J3. Now, what the data it strobes actually is might require more than just a logic probe or scope - maybe a separate test jig that can power the keyboard and latch it's data for checking?

  4. #14
    Join Date
    Jan 2011
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    I'm still mastering my scope but as far as I can tell, yes, data is being generated on power up. Take that with a grain of salt though. I've also checked for pulses as keys are being pressed, things seem to line up with the Theory of Operation, anyway.

  5. #15

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    If you're getting a good data-ready indication from the keyboard at power-up and nothing's being displayed at the monitor prompt I'd think the problem is on the mainboard. Obligatory question: are the power rails good from a power-up (and do they stay good)?

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