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Thread: DEC Rainbow modern display options

  1. #11

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    Search for gbs8200 on ebay. I found one for ~20$ shipped.

  2. #12
    Join Date
    Mar 2008
    Location
    Westchester County, NY
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    1,263

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    Quote Originally Posted by 2icebitn View Post
    Search for gbs8200 on ebay. I found one for ~20$ shipped.
    That is good, but for anyone considering this board for VR241 replacement, you will also need an LM1881 to separate the synch pulses.

    Lou

    PS. For reference, here is a thread I started five years ago on this topic : http://www.vcfed.org/forum/showthrea...nbow-VT240-etc . It may be useful.
    Last edited by Lou - N2MIY; June 21st, 2018 at 04:05 AM.

  3. #13
    Join Date
    Jun 2018
    Location
    Troon, Scotland, UK
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    Thanks for all the replies, I didn't expect so many!

    Unfortunately the VR201 I received with the machine was thrown out, it never had a VR241 with it despite having the graphics option (which I have successfully ran diagnostics on) for some reason. I'm guessing that's because the main use for my Rainbow was running dBase under CP/M. The VR201's CRT was covered in lots of cataracts and the capacitors must have leaked really badly as an unbelievably large amount of red goo/liquid was leaking out of it. I guess someone with a lot of time and patience may have been able to attempt a repair, but it was beyond my ability to do anything with sadly.

    I think I've settled on trying to use a GBS 8200 and sync separator to connect a VGA monitor as I managed to pick one up for 20 shipped and have the bits to build a sync separator based on the LM1881 on the way as well. Even if its not perfect, it'll be a lot better than any of the solutions I've used to get a video output from my Rainbow so far, so for the price I'll be quite happy if it all works. I'll report back on how I get on as I should have time to get it all built and set up next week providing all the parts arrive on time.

    I have already made up a cable to go from the Rainbow's video output to VGA so I should hopefully be all set after I have pieced together the VR241 replacement from the GBS 8200 and LM1881

  4. #14
    Join Date
    Jun 2018
    Location
    Troon, Scotland, UK
    Posts
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    Hi, just posting a quick update on how I got on with my quest to get a colour monitor working.

    I did go down the GBS 8200 route at first and built a sync separator for it. This did work and with some adjustment, the left hand side of the screen was intact, however the output had quite a bad green tint to it when displaying in monochrome and occasionally it would loose sync. I never found out what the cause of this was, sometimes it worked fine and others it didn't. When switching between DOS and Windows 1.0 it would also need the image readjusted on the GBS 8200 itself, so while it was an improvement in many ways, it wasn't perfect.

    Eventually, due to having enough other machines that could take advantage of it as well to justify the high cost, I invested in an Open Source Scan Converter (OSSC). This worked great with the Rainbow out of the box using the Rainbow to VGA cable I made earlier for the GBS 8200 board. All I had to do was set the AV3 (VGA) input to expect RGsB and the Rainbow worked first time. I did have issues with the left hand side of the screen still being cut off when using my TV, however on connecting to the HDMI input on my PC monitor, these issues vanished and I had a nice clear and full image from the Rainbow I also didn't have to make any adjustments when the video mode of the Rainbow changed when switching between DOS and Windows like with the GBS 8200.

    If you can justify the cost, I would recommend the OSSC over the GBS 8200 as it works much better out of the box especially when used with a PC monitor instead of a TV and also does not require a separate sync separator circuit. Here is a video I made of it in action


  5. #15
    Join Date
    Aug 2006
    Location
    Chicagoland, Illinois, USA
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    Thanks for the update! Someday I'll run out of CRT318h monitors for my M24 series and will have to do the same. The OSSC doesn't always work with every input and output combination, but when it does work, it works great.
    Offering a bounty for:
    - The software "Overhead Express" (doesn't have to be original, can be a copy)
    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Documentation and original disks for: Panasonic Sr. Partner, Zenith Z-160 series
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  6. #16

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    One word reply. Smashing.

    You could also go with one of these, purported to work vintage gear by at least 2 forum denizens:

    https://www.ebay.com/itm/NEC-MultiSy...53.m1438.l9372

    Cheap if you're in the US and maybe Canada. Or find an equivalent in your area. I think it has to be 19" and have an fxp or uxp suffix.

    Is it more economical to build it as a kit or source your own parts? The OSSC that is.

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