[sdiy] P600 - weird pitch bender behaviour

[Florian Anwander]

Hello,

I recently had the P600 of a friend on the bench with a weird behaviour 
of the pitch bender:

The bender does not bend down, and when it bends up, then at the last 
10% of the movement, the pitch jumps for about three or four half notes. 
Until to that point the bender covers a range of around two to three 
half notes.

The synth itself is tuned about three half notes to low. The highest 
setting of the tune potentiometer is still a half note too low.

The voltage at the input of the 4067 coming from the bender changes 
continuously from 0V to ~ +5V. The 7805 regulator on the panel board 
works fine

The potentiometer is ok (I interchanged the wires of the bender and the 
mod wheel). The mod wheel and all other potentiometers works fine.

I replaced the 4067 without a change.

I am now quite at the end of my ideas. The only assumption would be that 
the complete A/D-D/A thing is wrong aligned in a funny way, that it does 
not cause other problems but the all over tuning.


Any hints where to look for?


Florian

PS: unfortunately the synth is back at my friend and it is quite an 
effort for him to bring it in my house. So I don't want to shoot in the 
mist the next time he is coming by.
-- 
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