In setting up the K8055 boards from our most recent shipment we have found a few boards where the ATT1 pot does not get up to the 255 maximum setting. On those boards, if we work the pot several times across the full range they eventially allow us to reach the 255 setting.
As we use the K8055 with both the ATT1 and ATT2 pots at full scale perhaps we should be putting a fixed resistance, certainly in the place of the ATT1 pot. We have not had any problems getting the ATT2 pot to the 255.
Cheers,
Bin