9000 VAX wrote: Most likely problem: your flyback shorted out. DEC used lousy flyback transformers, and they were always my biggest problem with all the VT terminals. They would short out (cracking the ceramic shell and oozing black goo that would then harden), and often taking out a driver transister too. You can repair this problem with a new flyback (probably going to be hard to find), and a new transister. Been there, done that (many times), got the T-shirt.

OK, your PSU is tripping. It's trying to start up, then shutting down because it detects an overcurrent, then trying again. I didn't think the VT220 PSU did this (it's not a mains-side switcher). The VT320 certainly will (can I just check you are talking about the 220). The fact that the LEDs come on suggests the problem is not on the 5V line, since that must be coming up to power said LEDs. Most likely, and it's a total guess without seeing the termianl, you've got problems in the line output stage (horizontal output stage to you, I guess). Either the transistor has shorted, or the (flyback) transformer has failed, possibly taking the transistor with it. Seen it happen far too often on the VT320... Start by pulling the case, finding the flyback transformer, and finding a power transistor with the collector connected to one of the transformer pins. That's 99% likely to be the line output transistor. Desolder it and check it. -tony