Poselesta II input output diagnostic problem

I make diagnostic of inputs by Program 79 and N5 and I can see a lot of inputs in
state logic "1" even if I disconect (or not) all input conectors. Most logic "1" I can see
on the Port 2 A and Port 2 B.
I opened Poselesta II box and I check all signals from the output of the SFH600-2 , through
A inputs and Y outputs of the SN74LS14, through flat cable to the PC board with pheripherial
interface 8255 and processor 68B00. Electricaly I see logic "0" (0.1VDC) on the Port 2 A and B. Must I
replace processor or 8255 or must I replace whole PC board or something else is problem.