Kawai Synthesizers

Hello
I bought Kawai k1 II synth (second hand)severall days ago.I cleaned 
everything including the contactacts.The problem that I have is 
this: 
 Every 9-th key from the keyboard (going downwards from the top 
key "C" to the first key "C")sounds louder than the other keys.They 
don't have sensitivity,they just sound louder than the rest of the 
keys even when you apply the same pressure.
 I don't think that the dirt and dust are the problem,because every 
9-th note (including the last key"C")makes the problem.
 Can anyone help me with this problem and tell me more specific what 
to repare?
Thank's everyone in advance
Igor

Sensitivity or MIDI note-on velocity is measured by
the time from when the key starts moving from the top
to the bottom of the keystroke. Each key has two
switches.  One opens when the key starts moving down
and the other opens when the key reaches the bottom of
the stroke.  The switches on the keys themselves are
OK or there would only be one or more random keys with
problems, not one in nine.

  There must be a chip that is reading nine keys at a
time and measuring this interval on the one that got
pressed.  On a good key, press it down a little and
find where the logic is changing on the board.  See
where it changes again when that key reaches bottom.
Test again with a bad key.  With a continuity meter,
check if the connection is broken between the leg of
the chip and the trace on the printed circuit board. 
It is either a bad solder joint or a bad chip.  If the
trace shows that switch is working on the bad key and
the pin on the chip that is supposed to be connected
to to that trace shows no activity, then resolder the
connection between the pin and the trace.  Otherwise
try and replace the chip.

  Good luck.

Alan Probandt
Portland, Oregon


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Hi Alan
Thank you for your reply,but can you tell me more speciffic which chip or connections and on wich board to look for?Because I'm not technician,but my friend is.I had a problem before,the first 8 keys were not working and I sent e-mail to kawai.They responded and told me exactly wich connection was bad and they sent me scheme of the board,so my friend found it right away and resolder it,so the problem was fixed.
 Please help,if you can
Thank you again
Igor
Alan Probandt <alan_probandt@...> wrote:
   Sensitivity or MIDI note-on velocity is measured by
the time from when the key starts moving from the top
to the bottom of the keystroke. Each key has two
switches.  One opens when the key starts moving down
and the other opens when the key reaches the bottom of
the stroke.  The switches on the keys themselves are
OK or there would only be one or more random keys with
problems, not one in nine.

  There must be a chip that is reading nine keys at a
time and measuring this interval on the one that got
pressed.  On a good key, press it down a little and
find where the logic is changing on the board.  See
where it changes again when that key reaches bottom.
Test again with a bad key.  With a continuity meter,
check if the connection is broken between the leg of
the chip and the trace on the printed circuit board. 
It is either a bad solder joint or a bad chip.  If the
trace shows that switch is working on the bad key and
the pin on the chip that is supposed to be connected
to to that trace shows no activity, then resolder the
connection between the pin and the trace.  Otherwise
try and replace the chip.

  Good luck.

Alan Probandt
Portland, Oregon


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Hello,

  I have never worked on a synth keyboard but I am
very interested in learning them.  I am an electronics
technician with experience in microcontrollers and
programming.
  If you have the K1 schematic in digital form, such
as a PDF file or GIF file, you could attach it to an
e-mail message.  With the schematic I might be able to
suggest which chips to examine.  If the schematic is
on paper and you have a scanner, then I suggest
scanning it at 300 dots-per-inch, 2-color (Black and
White only, not grey scale) and saving the scan as a
GIF (not JPG) file.  That makes a very detailed, but
compact, file of the schematic.
  I hope that I can be of more help.

Alan Probandt
Portland, Oregon USA

--- igor nikolovski <pianoigor@...> wrote:

> Hi Alan
> Thank you for your reply,but can you tell me more
> speciffic which chip or connections and on wich
> board to look for?Because I'm not technician,but my
> friend is.I had a problem before,the first 8 keys
> were not working and I sent e-mail to kawai.They
> responded and told me exactly wich connection was
> bad and they sent me scheme of the board,so my
> friend found it right away and resolder it,so the
> problem was fixed.
>  Please help,if you can
> Thank you again
> Igor
> Alan Probandt <alan_probandt@...> wrote:
>    Sensitivity or MIDI note-on velocity is measured
> by
> the time from when the key starts moving from the
> top
> to the bottom of the keystroke. Each key has two
> switches.  One opens when the key starts moving down
> and the other opens when the key reaches the bottom
> of
> the stroke.  The switches on the keys themselves are
> OK or there would only be one or more random keys
> with
> problems, not one in nine.
> 
>   There must be a chip that is reading nine keys at
> a
> time and measuring this interval on the one that got
> pressed.  On a good key, press it down a little and
> find where the logic is changing on the board.  See
> where it changes again when that key reaches bottom.
> Test again with a bad key.  With a continuity meter,
> check if the connection is broken between the leg of
> the chip and the trace on the printed circuit board.
> 
> It is either a bad solder joint or a bad chip.  If
> the
> trace shows that switch is working on the bad key
> and
> the pin on the chip that is supposed to be connected
> to to that trace shows no activity, then resolder
> the
> connection between the pin and the trace.  Otherwise
> try and replace the chip.
> 
>   Good luck.
> 
> Alan Probandt
> Portland, Oregon
> 
> 
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