So if all LEDs remain on, that most likely means the CPU is not able to execute
instructions at all.
It might mean a busted CPU, busted ROM or CPU bus, or missing power or clock.
Yes,
that's exactly my feeling... so a schematic would be very good to try to
diagnose an evident problem as missing signals,
etc, knowing what they should be from the circuit diagram.
I will try to check something easy at first, knowing the pinout of the
microprocessors...
but after that I suspect it will be harder.
Andrea
