This is my first post, so I apologize if it's not in the right area.
I have a Atari 400 computer that I restored and have working with the exception of a keyboard issue. If I boot the 400 with no cartridge, the Memo Pad comes up but I cannot type anything. None of the keys work except the system restart key located on the top right of the keyboard. If I insert a BASIC cartridge, I get the READY prompt but if I press any button on the keyboard, the 400 locks up and the screen kinda gets random horizontal block lines across it. Sorry, it's hard to explain but I can attach a photo. Was hoping someone can point me in the right direction in what IC I should try to replace first? Maybe the POKEY chip but the controller port works as game cartridges seem to work with the controller port #1, which is tied to the POKEY chip.
Any help would be greatly appreciated!!