I have a non-functional Tektronix 7704A mainframe with a full array of plug-ins available for pickup. There is text on the display but it won't show the horizontal trace. Let me know if you're able to

Thank you gentlemen. I will investigate and reply when I have more information. Ambrose

Hello everyone, I'm new to the group and I have a 7704A that isn't working. I was lucky enough to pick this unit up as a giveaway and I need help to get it working. The 7704A mainframe (without any pl