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iainjh

Current best S-video /picture improvement mod for 800XL?

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hi all

 

whats the best s-video /picture improvement for a pal 800xl please?

 

googling usually brings this one up (ultra video) http://www.atari8.co.uk/downloads/UltraVideo%20XL%201.0.pdf

 

has anyone here done it and can report its the best current option? looking at the schematic seems to bring up a couple questions re how well it will actually work, so please if anyone can pitch in with links or confirmation, that'd be appreciated.

 

it needs to be a simple and reliable mod, cheap, standard (no vxbe etc) just s-video and any simple improvements as ultra video suggests

 

cheers!

 

Iain

 

:)

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There's a guy on eBay that sells bare or populated boards ($12 or $45, respectively), that connect directly to GTIA and bypass the whole Atari chroma/luma mess. While a bit pricy, I got one and installed it in 800XL, and it looks much better than my SV 2.1 1200XL. No lines whatsover.

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...This topic usually appears "shrouded" by countless posts, multiple threads, etc. (and lots of information) but little "definitive", straight-forward answers.

 

The reality (as it may surprise you) is that the 800XL (in the NTSC domain) requires ABSOLUTELY MINIMAL changes to its on-board video circuitry in order to drive out a decent, clean s-video signal. That is right, NO internal boards, no need to remove RF modulator, no need to mass-murder passive components, add "pick-up" resistors, etc., (assuming a decent CRT/LCD TV set or LCD+Video Processor combo, and you are not going to use miles-long video cabling).

 

It would all depend on your MoBo revision. In general terms, all you need to do is (again, for NTSC version):

  1. REMOVE C56 capacitor (if present). This will dramatically improve sharpness and "edge"-definition.
     
  2. Lift C54 right-hand side, preferably by inserting an on-off switch (if you want to preserve composite out). This will almost COMPLETELY remove vertical banding (present on Luminance-Y signal).
     
  3. Solder Chroma-signal wire from R67/R68 junction, to chroma pin in video port. This will enable the missing chroma-signal on the 800XL (the majority DO NOT have it enabled). No need for pick-up resistor (of any kind).

 

THAT'S IT. The rest is pretty much redundant or unnecessary. Just adjust Brightness and Saturation on your CRT/LCD display, to your taste.

 

 

Here are actual PHOTOS (from 52 inches LCD screen) of how the above solution ends up working (make sure you enlarge for max. detail):

 

post-29379-0-10712300-1338670671_thumb.jpg post-29379-0-61385100-1338670726_thumb.jpg post-29379-0-17534800-1338671157_thumb.jpg post-29379-0-84119200-1338671184_thumb.jpg

 

LastWord included, because not only is a de-facto must-have app., but because it GREATLY benefits from decent / clean sVideo output.

 

Enjoy!

post-29379-0-53132300-1338671357_thumb.jpg

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There's a guy on eBay that sells bare or populated boards ($12 or $45, respectively), that connect directly to GTIA and bypass the whole Atari chroma/luma mess. While a bit pricy, I got one and installed it in 800XL, and it looks much better than my SV 2.1 1200XL. No lines whatsover.

Some of the circuity on this board replicates part of the video circuity on the Atari models, with some changes in component values. The main difference is that it replaces transistors with an IC to buffer the Chroma/Luma signals and to create the Composite signal, this IC isolates Chroma/Luma from each other and prevents feedback into the Luma signal which causes vertical lines.

 

I believe the following post contains a schematic of the board being sold on ebay, although the schematic could be of an older revision.

http://www.atariage....75#entry2251742

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You can replace C15 and L15 with a wire to improve the video and R63 with a wire to restore +5v to SIO. Use the Composite output as the Chroma source in s-video mode. I do this on all my 1200XLs.

 

C15 and L15 are just above U27. R63 is just to the right of Q3.

 

You may also get sharper characters if you replace C60 with something like 39pf or so. C60 is right above Q11.

 

Bob

 

 

 

Is there something similarly simple that can be tried on a 1200XL?

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Some good info in this thread!

 

The BEST video I've ever achieved is Super Video 2.1 on an 800XL. It is the best in my fleet -- but it is a fair amount of work, especially if you desolder the numerous components instead of just "piggybacking" where applicable. Very good 800XL video is available from a lot less work as detailed in this thread:

 

http://www.atariage.com/forums/topic/41580-quick-easy-video-upgrade-for-800xl/

 

Has anyone tried one of the KJMann or other "bypass" solutions in a 1200XL? It strikes me that if it would work, it would be a good solution for the 1200XL's video ills.

 

-Larry

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The last KJMann mod I tried on a 1200XL didn't fare so well. The main problem was vertical banding. The 1200XL's video output seems the most challenging of all, which is the main reason I ended up sticking a VBXE in there. :)

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I tried KJmann's board in my 800xl last year and wasnt happy with it at all. Ended up removing it and doing the ultra revision. It's nicer but still has some banding. I also tried the easy way like Faicuai but it was terrible on my machine. That new board looks quite interesting. I may have to pick one up to try.

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I tried KJmann's board in my 800xl last year and wasnt happy with it at all. Ended up removing it and doing the ultra revision. It's nicer but still has some banding. I also tried the easy way like Faicuai but it was terrible on my machine. That new board looks quite interesting. I may have to pick one up to try.

 

...Based on your historical experience, and based on the simplest possible mod. you can perform, it is quite probable that your machine's video circuit is already crooked.

 

Could you post a picture of the video section from C56-corner (even if not present) to C54, including R67/R8, from the top-side of the MoBo, in focus (and good light) in order to see what is left in there?

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Sorry.. didnt really have plans to take it back apart at the moment. I dont remember exactly what i've done at this point, but many parts have been removed or changed now. I started with the simplest, then went kjmann, then kept adding the mods in the super and ultimate instructions because I wasnt happy with the outcome. What I have now is very nice, but there's some vertical banding. Mainly only noticeable on the blue basic screen. Games look awesome.

 

Using a short svideo cable to a widescreen 30" HD CRT.

 

At one point with the kjmann board I accidentally broke the luma wire. In black and white its amazing how clean and clear the picture is.

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It's some sort of law.. lol Anyway, I had no want to reopen my XL, but I just accidentally pulled loose my sound connection while playing ultima IV with the xl on my lap. So.. had to open her up. Here's a couple pics for the curious.

 

atari004.jpg

 

atari007.jpg

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is your monitor a 16:9? this can also cause verticle banding... and no mod will fix it, as its an issue with the monitor not the A8... also common on LCD's...

 

sloopy.

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Hello guys

 

Jürgen (tfhh), who sometimes visits AtariAge, seems to have come up with a very good mod. That is, if I understood correctly. Not sure if he describes it somewhere in English.

 

Mathy

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Hi,

 

i´m working on a complete guide for video modifications for XL and XE series. This guide will include ALL necessary informations for each mainboard versions with detailed photos from each step. Some people say, it´s not necessary to do a lot of work, my opinion is another: it depends very strongly on the video format (NTSC or PAL) and the connected monitor or television. So I use my experiences after modding dozens of machines. I don´t want big discussions, I will spread my informations and experiences I made - everybody can be feel free to use it or not.

 

Juergen

Edited by tf_hh

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It's some sort of law.. lol Anyway, I had no want to reopen my XL, but I just accidentally pulled loose my sound connection while playing ultima IV with the xl on my lap. So.. had to open her up. Here's a couple pics for the curious.

 

atari004.jpg

 

atari007.jpg

 

 

THANKS for going the extra mile and posting your machine "guts"... :) (forgot to add that you have what's probably the BEST MoBo edition for the 800XL). It looks identical to both of my units, and should Rev.C-HongKong, fully-socketed, thick-plate shielding and screw/BOLTS for shield attachement (not ugly "screw-in" as I have also sitting around here).

 

Well, it looks pretty much as I thought: most passive-components of video-path's final stage have been "mass-murdered" (R56, R57?, R67, R68, etc.), does not look like composite output remains active, RF modulator gone, I would also bet that your luma-signal is now over-driven, etc. One good thing is that I could not find C56, which is Ok.

 

At this stage is not easy to come up with a specific recommendation other than a) bringing it back to its factory-spec, with the high-quality passives (factory-spec. resistors and capacitors,etc.), or b) take advantage of one of those ebay Video-mods (cost around $45), now that most components have been ripped-out/crippled.

 

As I mentioned before, THERE IS INHERENTLY NO NEED to modify the 800XL video-out if you wich to extract a decent / stable s-video signal (at least up to Rev.C, in the NTSC domain). As for the Rev.D that I have had the chance to inspect (also on the Scope), it does not need either any major change, either, as C56 seems already gone, thus leaving you with only C54-switch and Chroma-pin signal as your ONLY really needed mods.

 

Also, decoupling Y-signal from Composite-Video sum-stage (at R56) WILL NOT REDUCE vertical banding to its fullest. It is the CHROMA signal (C54) which needs to be decoupled/disabled while LEAVING Luma enabled (R56), at that combining point (again, for best possible sVideo output with on-board Factory components).

 

Any further steps performed over the EXISTING implementation seem, in general, either redundant or hit/miss, unless you inherently CHANGE the approach in which Y and C signals are handled/combined (which means a new final video-stage). Many of these things are harder to confirm because not everyone has immediate access a Scope that can automatically or easily trigger NTSC signals (or PAL signals), by either any given (user-selected) Scan-Line, or fields, or group--of-fields, etc. You are pretty much BLIND if you do not have such instrument PRIOR to applying any video-mod recipe that ALTERS values, resistors, amps, etc., from your existing MoBo configuration.

 

It is what it is, folks. There is not that much left to do.

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Bare board here:

 

eBay Auction -- Item Number: 1808921545031?ff3=2&pub=5574883395&toolid=10001&campid=5336500554&customid=&item=180892154503&mpt=[CACHEBUSTER]

 

Interesting - hadn't seen this before.

 

Bought a bare board, have a couple HC4050's and lots of 75ohm resistors laying around. Will have to order some of the parts from Digikey I guess. Going to stick it in my poor 600XL in which the video circuit is now barely recognizable from all the experimenting and yank some of that crap and the RF modulator completely out and do it right with pretty jacks, etc.

 

This video board actually seems like a pretty good idea, seems to replace the whole video circuit with something resembling the original but a bit more modern. Seems to filter audio some too. I'm pretty optimistic actually. Has an FMS6400 IC on there for video filtering and generating composite signal. Composite should probably be much nicer looking as well.

 

I had little luck with the KJmann board, it was a good effort but it does NOT solve the vertical banding issue whatsoever and may make it slightly more annoying due to a less fuzzy image. You can do the same thing yourself with a couple in-line resistors and some wire. Better than RF in a 600XL I guess.

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Hey! Do let us know -- I've got a couple of 600XL's that I'm very unhappy with.

 

-Larry

 

Bare board here:

 

eBay Auction -- Item Number: 1808921545031?ff3=2&pub=5574883395&toolid=10001&campid=5336500554&customid=&item=180892154503&mpt=[CACHEBUSTER]

 

Interesting - hadn't seen this before.

 

Bought a bare board, have a couple HC4050's and lots of 75ohm resistors laying around. Will have to order some of the parts from Digikey I guess. Going to stick it in my poor 600XL in which the video circuit is now barely recognizable from all the experimenting and yank some of that crap and the RF modulator completely out and do it right with pretty jacks, etc.

 

This video board actually seems like a pretty good idea, seems to replace the whole video circuit with something resembling the original but a bit more modern. Seems to filter audio some too. I'm pretty optimistic actually. Has an FMS6400 IC on there for video filtering and generating composite signal. Composite should probably be much nicer looking as well.

 

I had little luck with the KJmann board, it was a good effort but it does NOT solve the vertical banding issue whatsoever and may make it slightly more annoying due to a less fuzzy image. You can do the same thing yourself with a couple in-line resistors and some wire. Better than RF in a 600XL I guess.

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