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Elec. Keyboard: board-level design

Discussion in 'Electronic Repair' started by Puddin' Man, Dec 18, 2007.

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  1. Puddin'  Man

    Puddin' Man Guest

    Thanks for previous help. Yeah, it's a learning experience: my expertise
    is miniscule.

    The EKB is Yamaha PSR-12, about 20 years old. I can leave it powered
    for a long time, no problem. Play it for 30-90 seconds and it
    freezes up, keys don't work.

    It has 4 boards:

    1.) "1684 PN1" - large board with markings for voicings
    2.) "1684 PN2" - large board with markings for effects, etc
    3.) Power Supply - from batteries or converter
    4.) Switch - main power switch and master volume

    I'm just trying to get a feel for what functions are implemented
    on what boards ...

    The headphone jack/speaker connects to 3.) via 3-element black wire.

    1.) connects to 4.) via 2-element black wire.

    4.) connects to 3.) via 8-element ribbon cable.
    The 8 elements are as follows:

    Label Color
    ----- ---------------------------
    E white/pink stripe
    5v white/gray stripe
    B white/yellow stripe
    T white/blue stripe
    M white/pink marking
    S white
    E bare metal
    E red

    I get the feeling I stand no chance of trouble-shooting this unit
    unless I can grasp the functions of this 8-element ribbon cable
    (on *some* level).

    Anybody got a feel for how the E B T M S E are coded?

    I pulled 1.), cleaned and inspected, replaced it. No hep'.

    Thanks,
    Puddin'


    "Well, there's two trains runnin'.
    Ain't neither one goin' my way.
    One run at midnight,
    the other run just before day."
    - from "Still A Fool", Muddy Waters, maybe 1949
     
  2. js

    js Guest

    From one hacker to another:

    Find "that one guy" in your town who repairs these things, and let him do
    it. He has the service manuals, the substitute part specs and the experience
    that you won't find in 100 hours of web searching.
     
  3. Puddin'  Man

    Puddin' Man Guest

    What if he don't floggin' exist???

    P

    "Well, there's two trains runnin'.
    Ain't neither one goin' my way.
    One run at midnight,
    the other run just before day."
    - from "Still A Fool", Muddy Waters, maybe 1949
     
  4. boardjunkie

    boardjunkie Guest

    I'd check the supply voltage(s), look for cracked solder, maybe flex
    the board to see if theres any intermittant connections. Other than
    that there's not likely anything you can do with it since its probably
    full of custom ic's. Not worth the trouble if you ask me.....unless
    its a Moog, Arp, Sequential, etc.
     
  5. js

    js Guest

    Then you haven't looked hard enough.


     
  6. wc3p

    wc3p Guest

    Mr Puddin,

    I couldn't help but think about the time my Yamaha kept locking up due
    to a screwup with MIDI commands. Does yours have MIDI in and out?
    Check your settings; shut MIDI off if you can and try it again.

    Good luck,

    Bob
     
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