finally manage to debug my P6. I've changed the chip RAM and IC30 (it had not been replaced by previous owner, even after the battery leakage. Looking at pins, I found that the pins were quite dull). So don't know if it was because of the RAM or IC30 but quite sure the culprite was the last one. ;))
thanks a lot for tour help Johannes, I've learned a lot.
rgds,
Ed.