keyboard problems

i collect and repair very old computers
last week i accquired an old i80386 SX 20 mhz.
since the 2nd time i turned it on it the prompt to enter the bios doesn't work anymore and even if i use the protuguese keyboard codepage in msdos the keyboard keeps acting like a U.S. one.in windows the keyboard acts ok.the lights of the keyboard don't work.the problem IS NOT the keyboard because i have already replaced it and it is not an OS problem.i have also cleared the cmos and nothing.the pc is a PHILIPS P3348 and the os is MS-DOS 6.22 and Win 3.11.do you think it is a faulty keyboard controller chip?thanks