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  • EEVblog #256 – Yamaha PSR-80 Keyboard Teardown

    Posted on March 11th, 2012 EEVblog 11 comments


    Teardown photos here:
    http://www.flickr.com/photos/eevblog/sets/72157629559990345/
    Sagan needs his keyboard repaired, or daddy is in the dog house. Gotta tear it down, to fix it…

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    11 responses to “EEVblog #256 – Yamaha PSR-80 Keyboard Teardown” RSS icon

    • Nice video, as usual.

      On some keyboards I’ve seen a double contact under every key, arranged in a way so that they close very quickly one after another when the key is depressed. The MCU on board measures the time between the two events and translates it into key velocity. There’s also usually a single long contact under the whole keyboard fixture used to send monophonic aftertouch.
      A single contact usually means the keyboard isn’t velocity sensitive, but should these contacts have an useable resistance value that depends on how fast/hard you hit the key, they could be used to get both velocity and poliphonic aftertouch by sampling both the initial resistance and its variation before the key is released.

    • Heatsink grease is made with zinc oxide, not beryllium oxide. You almost certainly use the same sort of stuff on Sagan’s behind, so don’t worry.

      Cheers

      Phil Hobbs

    • Hi Dave and others that may be interested

      Dave made the right assumption that getting a slider pot to fit would ‘take some time’
      Unlike rotary pots, i have found that slider pots have chnaged in their mechanical construction (read dimensions and mounting points)over the years, so when servicing old equipment replacement isusualy not an option.

      I have been successful in pulling the sliders apart. They come apart very easily.
      There are usually only a few problems
      1) the tarck has gone open circuit. I jusy get some conductive ‘paint’ and bridge the tracks where the break is
      2) the slider contact wears out or breaks. I have been successful in grafting the contact from a rotary pot onto what remains of the slider contact. Takes a bit of coordination (its very fine work)

      Both the above solutions will resurrect some old historic pieces of equipment

      Robert

    • What’s with all the electrolytics being spaced away from the PCB? Differrent lead spacing than the PCB layout, so they can’t fit flush?

      • It’s definately common for electrolytics to be spaced away in old equipment.. My presumption was so they were further away from the heat when soldering. As bad as electrolytics are now for heat/life/tolerances, they used to be far far worse.

        • I may be double insurance too… :)
          I saw several times the rubber base on radial electrolytics acting as the release pressure valve as well.
          In these cases, either the top was a solid aluminum can or the hashed top did not crack open, thus the bottom was the only way out.

    • Very interesting. First time I’ve seen the DIL package with staggered pins or the SIL package.

      I didn’t catch why Dave had to drill a hole in the case to fix the faulty slide pot. Anybody?

    • pls… help to find the value of IC number 10, 4pin with heat sink. model psr-80

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