So, my original Intellivision (brown unit) seems to work fine. But it will not operate an Intellivoice consistently. I've tried two different Intellivoice units. When I plug an Intellivoice in the unit displays a black screen but after a time can be reset and the game will display, most often with garbled sounds and an attempt at saying, "Mattel Electronics Presents (game name)". Seems like something is warming up and getting better but not quite making it where it needs to. Power? IC? Any ideas?