I have a #250407 board thats giving me Black Screen. I checked the MPU with Logic Probe and I see that Address Lines A8,A9,A12,A13,A14,A15 are usually stuck High(should be Pulse). Sometimes when I turn Power Switch On/Off they stay Pulse(normal) but Screen is still Black,No Border
Checked the following Chips in a known working board:
-All 8 RAM Chips
why are 6 address lines stuck High?