Piano Technics PX9 problem

Discussion in 'General Electronics Chat' started by jojo005, Mar 11, 2017.

  1. jojo005

    Thread Starter New Member

    Jan 16, 2017
    9
    1
    I everyone,

    I have this keyboard and there is a regular problem with keys.
    They works 8 times out of 16. It sounds 8 times and nothing 8 other times.
    Which components should I change ? Looks like an dead IC...
    I didn't found ht schematics.
    I can send pictures if it can help.

    Thanks !
     
  2. absf

    Senior Member

    Dec 29, 2010
    1,869
    511
    I'd suspect the contacts underneath the black and white keys....
    How old is the keyboard? Has you changed any parts after you purchased the instrument?

    Take a look at this utube video and see if it helps you to fix your problem....
    You keyboard might be more difficult to remove than the one in the video.



    Allen
     
    Last edited: Mar 11, 2017
  3. jojo005

    Thread Starter New Member

    Jan 16, 2017
    9
    1
    Thank's Allen,

    The guy who sold me the keyboard has cleaned the contacts ( but I don't know how).
    And the thing which makes me telling that's not the contact is the regular sound/no sound.
    Of 16 hits only 8 woks, etc with all keys.
    I never have changed any components.
     
  4. wayneh

    Expert

    Sep 9, 2010
    15,000
    5,453
    Wow, so that is repeatable and predictable, 8 on and 8 off? Weird.
     
  5. absf

    Senior Member

    Dec 29, 2010
    1,869
    511
    Then I guess you must get the service manual of this model in order to find out what's the problem.

    On the PX107 digital piano, there is a "Gate Array" and a "1K bit ROM" on the keyboard PCB. Not sure how the PX9 decodes the key positions. Some models have a few 74LS138 on the PCB for decoding.

    Allen
     
  6. jojo005

    Thread Starter New Member

    Jan 16, 2017
    9
    1
    I checked the service manual but nothing about gate array or schematics.
    This problem seems weirds but if it's repeatable it's should be simple (I guess :)
    I will open the keyboard and tell you about the IC I see
     
    absf likes this.
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