Image Map Image Map
Results 1 to 4 of 4

Thread: Tandy 2000 video failure modes

  1. #1

    Default Tandy 2000 video failure modes

    All --

    I'm helping someone out troubleshooting a Tandy 2000HD with a hi-res video board that's exhibiting the following problem (see picture below). The picture has both mono and color monitors running simultaneously and both exhibit the same screen artifacts. So, it would seem that the problem is on the system board rather than just the hi-res video board (which is where it was noticed first, leading us to try the monochrome). I looked at the service manual and I didn't immediately see a big troubleshooting tree, so I thought I'd post it and see if anyone has seen this before.

    My first thought is with the video buffer memory and/or the CRTC that's on the main board, but I didn't want to recommend soldering/desoldering unless I could narrow it down. The Standard Microsystems CRT 9XXX parts are still available on the secondary market, but aren't cheap.

    IMG_6678.jpg

    Any clues would be appreciated. Thanks!

    Rich

  2. #2

    Default

    Just a suggestion, pull the graphics card and test with just the mono monitor. I would also try a different dos image. If you determined the problem was on the Mobo, maybe the issue is video ram or ancillary logic and not the core video ic's.

    Somebody needs to study the signals on that Euro connector and figure out if it's compatible enough to connect a vga card to the thing.

  3. #3

    Default

    Quote Originally Posted by 2icebitn View Post
    Just a suggestion, pull the graphics card and test with just the mono monitor. I would also try a different dos image. If you determined the problem was on the Mobo, maybe the issue is video ram or ancillary logic and not the core video ic's.

    Somebody needs to study the signals on that Euro connector and figure out if it's compatible enough to connect a vga card to the thing.
    My buddy will pull the hi-res card and try it. The screen anomalies occur even during the POST, so it's likely not the DOS image.

    I think the RAM chips are still available on eBay (CRT9012??). Other logic, other than a few PALs, are still available.

  4. #4

    Default

    Well the bios is loaded from disk (and I don't mean io.sys, *the* bios, or much of what we call a bios). You probably know all this but if you power a 2k without any boot media, you will nearly immediately be greeted with the amount of installed ram. The entirety of what's entailed in the mobo boot rom I don't know. The bios (disk) seemingly doesn't include every aspect of post, because you get video without boot media. And duh a ram check.

    Ok whatever lol. Good luck with it. My 2ks aren't working at the moment so I can't be of much help. Too much on the docket presently to even get involved with that.

    Does your 2k work?

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •