Hi Joachim
Sounds like there's some voltage leaking into areas you don't want it.
First thing I'd try is giving the board a good clean with some isopropyl
alcohol.
Could be that at some point something has been spilled onto the board
and it's gone conductive.
Give it a really good clean using a cotton bud, and then try it again.
you may find it does the trick, or you may find that it reduces the
problem. If it reduces it, then you're on the right track and it needs
more cleaning.
If it makes no difference then it's back to the drawing board :-s
Hope that helps.
Bob
On 19/05/2013 10:23, joachim.milson wrote:
>
> Hi All,
>
> I acquired my CS80 (unit 1670) less than a month ago. It has a couple of
> known issues all bound to the keys.
> The one that could be fixed:
> - a sequence of 6 consecutive keys had neither AT nor IT. The faulty
> chip was a 4016 (Gates) on the TKC.
> - two keys had no IT but AT was OK. It took me some time to find out
> that this was due to the PCB holding the "IT/note" metal strips at the
> back end of the keys. I had to solder two short wires to bypass the two
> non conductive printed tracks, although nothing could be seen (no
> scratch on the PCB). Has someone already had this problem ?
>
> I'm stuck with the last issue (at least known to me for the moment).
> One AT sensor board seems faulty under one key (G#3).
> Here is a close-up of the faulty AT sensor board
> <http://groups.yahoo.com/group/yamahacs80/photos/album/1863574374/pic/56\
> 3904716/view
> <http://groups.yahoo.com/group/yamahacs80/photos/album/1863574374/pic/563904716/view>>
> Compares to the other tracks on the same board, nothing seems to be
> different.
> The problem is that the voltages at T3 are always two high:
> The voltages for a normal key vary (as I measure them) from -0.3V (not
> pressed) to 6.2V (pressed to the maximum)
> Under the faulty key, the values are 1,7V (not pressed) to 8.4V
> (pressed to the maximum).
> So the voltages seem to be shifted upward by 2 V under the faulty key.
> Certainly some printed resistor is faulty.
> The result is that, depending on the AT settings for the current preset,
> the corresponding note sounds a bit too loud and can even be heard when
> it should not.
> I switched the PCB with the last one on the right, so the problem is now
> on G#5, where it is slightly less audible, but still there (no miracle
> !).
> Is there a way to somehow repair this issue ? If not, has someone one
> such board (one for the black keys) in his spares stock and would accept
> selling it ?
> Any help will be appreciated.
>
> Thanks,
> Joachim
>
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>
>
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