Fix'n VT220s

Date: Sun, 1 Dec 2013 19:04:41 -0600 Subject: Re: Fix'n VT220s From: useddec at gmail.com To: cctalk at classiccmp.org Hi Chris, I remember 2 types of 220s, and have parts for at least one of them here. I would need the part number also. I have most of the VT100, 101,etc logic boards too. Thanks, Paul On Sun, Dec 1, 2013 at 2:26 PM, Chris Elmquist <chrise at pobox.com> wrote: > I recently "saved" a small pile of VT220 and VT100 terminals from a > barn in western WI. They were grubby and have various issues but I am > enjoying cleaning them up and making a few good ones from some bad ones. > > One of the VT220 is a very new vintage unit. Circa-1987, with some > components with date codes 1990. It has a totally different logic > board than earlier models I've worked on-- this one having a large PLCC > package in the center of the board which I assume is a custom device > integrating the video controller and much of the support logic since > there are considerably fewer parts on this board than the older ones. > Still an 8031 CPU though. > > This unit also has a totally different video monitor circuit than the > older ones and my problem lies somewhere on that board-- I am getting > a very dim image even though the CRT itself appears to be in very good > shape with no burn-in and otherwise crisp display. I think I've got a > high-voltage problem but without schematics to match this board, it's > kind of a crap shoot to start debugging. > > So, wondering if anyone has newer schematics or technical reference for > the VT220 than we find out on bitsavers? The bitsavers docs are circa- > 1983 so I am looking for something 1987 or later when it appears they > did a considerable redesign of the guts of this terminal. > > Chris > -- > Chris Elmquist > >