K8061 - Strange behavior of analog input 1 to 3


I just prepared the 8061 board as a follow up for an active 8055. After connection and loading the demo program (latest version drivers) directly I can see AD1 to AD3 getting input…not to much: AD1 up to 20, AD2 maybe up to 6, AD3 just sometimes up to 1 or 2…so degrading…

When I activate any off the digital outputs -> everything is ok. Then if I try all the analog inputs, all are working properly except when I give an input on AD1, I get again movement in AD2 and AD3…

Solution for the moment: always have a digital output to ON and avoid using AD1…but this means I loose 2 ports…

Any suggestion what I did wrong?

Thx & regards,

To locate the problem you may do following test:
Remove the Op-Amp IC10.
Put the jumper caps on AD1, AD2, AD3 and AD4.

Run the program. - Are there still these “idle” values in these three AD channels?

Here a link to download the circuit diagram of the K8061: box.net/shared/2o4jxf9yuu