Yamaha CS80

OK. Just been looking at the pic, and the service manual.
It could well be that the resistive print in that area is faulty either 
due to wear and tear, or just plain old age.
Looking at the service manual it suggests that on either side of the 
contact resistor (topologically speaking) are some resistors. If you're 
feeling brave you try adding a new resistor into the path to compensate 
for the error?

B
On 19/05/2013 11:31, joachim.milson wrote:
>
>
>
> Thanks Bob for your answer.
>
> I already cleaned the boards and sensors carefully.
> The contacts are very clean. I did it very carefully under a 
> magnifying lens. Also, I changed the sensor with an other one but the 
> issue is still there. So on my opinion, the problem is the PCB itself.
>
> Joachim
>
> 



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