Thanks for the link Steve.
I replaced the screen RAM and zeropage RAM, 2x74LS241 and 2x74LS245 but had no answer from the 710. Then I replaced the CRTC and 3x74LS157
that where a bit hot but nothing...the 710 doesn't want to work...EPROMS from the adaptors are good...I don't know what could be the problem as I don't have
an oscilloscope or logic analyzer at the moment...any suggestion is well accepted.
Thanks