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


iainjh

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I haven't tried it, but I believe if the GTIA socket on the Atari PCB is removed, the v2.2 PCB is assembled in the thin configuration, and the top RF shield is left off then I believe v2.2 will fit, although it will be a permanent installation. It's certainly not how I hoped it would have to be installed.

 

When installing the v2.0 PCB in my $11 Atari 800XL, I noticed faint vertical lines that weren't there on the Atari 5200. I assembled the kit as originally designed (with the chroma circuit nearly identical to the Atari 800) and the lines were just barely visible with s-video. No lines are present on a CRT, just on a LCD HDTV. I'm not sure why that is, possibly using the original monitor port with poor FR shielding?

 

Even with faint lines, the picture is still 10x better than original. I couldn't believe how bad the stock 800XL video was.

 

On the Atari 5200, the modified circuit had slightly better picture. Weird.

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  • 2 weeks later...

I'm attacking a 1200XL that has particularly nasty composite (see below). It's an almost-new mobo, purchased earlier this year (so it has had very few video mods).

 

It has had four based on earlier recommendations. I replaced L15 and C115 with 1 Ohm resistors and removed C60. And of course, I added a Chroma output line to the video jack. That's it, for now. Replacing L15 and C115 had some effect. Pulling C60 had a very significant effect on text sharpness. (BTW, the composite looked just as bad before and after pulling C60.)

 

Now some questions.

 

1) If you look closely at the S-video picture, you can see horizontal "streaks" randomly in the picture. These always are there in any S-video output. Worse on some machines, better on others. But that doesn't show up in the composite screens. Maybe it's just masked? Any thoughts?

 

2) This is related to #1 -- Several of the SuperVideo mods call for a composite disable switch. I never added this switch. Does it help "clean up" S-Video? I actually wouldn't mind disabling CV entirely -- I never use it.

 

3) Any thoughts on anything else to do to this 1200XL? I might add that I'd like to avoid the whole SV2.1 or ClearPic 2002 mods. I'd like 80% of the gain with 20% of the work if that is possible. (Notice how these numbers always seem to add up to 100...) The S-video is pretty acceptable right now with just the 4 steps already done, but if I could get rid of the horizontal streaks, that would be terrific!

 

-Larry

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1. S-video has a very high bandwidth on the LUMA and CHROMA channels, because they each have their own path. COMPOSITE chops off the bandwidth of both and merges them together. You see the lines because you're using a high bandwidth channel.

 

2. When you join the two signals together a little of each gets fed back into the other - LUMA leaks into CHROMA and CHROMA leaks into LUMA. This affects the clarity and purity of the signals in all modes. (S-video and composite) (that does not mean that you should delete composite on a 1200XL)

 

3. You hooked up the CHROMA line? I would not do that... Just use the COMPOSITE signal for CHROMA when you do S-video. On a 1200XL, you should get good video with just C115 (C15?) and L15. I don't see any streaks on my monitor.

 

Are you sure your cables are correct?

 

Bob

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Cables correct -- absolutely. C60 made a BIG difference. Not little -- BIG! Your Clear Pic 2002 says to remove C60 and so does SV2.1.

 

I've not had much luck using composite as chroma. Here is a screen shot with Luma + Composite as S-Video (presume this is what you mean). Note all the artifacting. It is clearly better overall than just composite, but not as clear or sharp as Luma + Chroma. "Streaks" are still there, but might be a little subdued. Not sure.

 

For comparison, here are a couple of pics from a SV2.1-modified 800XL. (Same cable). Composite is still blurred, but S-video is quite good to my eyes.

 

-Larry

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How do you get your pictures, Larry? They come out much better than mine do...

 

This is what I don't like about video tweaking. Everyone gets different results. Any of my 1200XLs with just the L15/C15 change (C60 in place) and using COMPOSITE for CHROMA look much better than your pictures. I say pictures because my pictures of my monitor don't look anything like real life. Yours may not either.

 

Even the middle pic shows color bleed into the character pixels - makes them pink-on-blue, rather than white-on-blue.

 

Here is a pic of my s-video. Just C15 and L15, using COMPOSITE for CHROMA.

 

 

Bob

 

 

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I cheat! My (only) display is a PC screen capture device. Specifically, an ATI All-In-Wonder card. All I need is a mouse click.

 

Yes, and another of the bad things about video tweaking is that everyone has different visual impressions of what they see. And you are using a CRT. I think if you were using a flat panel, you would see other things in the displays.

 

...still looking for suggestions. I'm not through with this XL, yet! ;)

 

-Larry

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  • 2 weeks later...

I installed the v2.2 s-video mod board in my 800XL and found the picture to be quite good, better than either version of the v2.0 board's schematic. There were no hints of vertical lines. Due to the limited height clearance, I connected it to the lifted pins of the GTIA with wires.

 

I have a new version 2.1 of the PCB designed without the 40p DIP pass-through specifically for most (if not all) Atari 8 bit computers. It installs like v2.0 but is smaller and uses the newest schematic. I'm not sure if I want to have it manufactured unless there is enough interest.

If anybody is interested in this improved Atari 8 bit s-video mod, PM me and if I get enough requests I'll have it made.

 

Not the best screenshot, but I currently don't own any Atari 800 games :(

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  • 2 months later...
  • 4 weeks later...

Version 2.1 of the s-video / composite mod for Atari 8 bit computers is ready. It's smaller than v2.0 and has much better picture quality. If anybody is interested, PM me. They're also on ebay.

 

The schematic is the same as v2.2 (for the 5200.)

 

 

I'm selling the assembled v2.1 PCB for $35.

The PCB only is $12.

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Has anyone put one of these boards in a 600XL or a 1200XL or even a 130XE? If put into a 600XL, does it replace the missing video components?

 

I'm interested in this, but really would like to know how it does in other than an 800XL.

 

-Larry

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Has anyone put one of these boards in a 600XL or a 1200XL or even a 130XE? If put into a 600XL, does it replace the missing video components?

 

I'm interested in this, but really would like to know how it does in other than an 800XL.

 

-Larry

It should work the same with any Atari 8-bit, it connects to the LUMA/CSYNC/COLOR outputs of the GTIA chip which is common to all except the early CTIA 400/800. It would probably be harder to install inside the RF shield of the 400/800 systems.

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If no one has ventured into these waters yet, then I might try one anyway. I can always stick it in an 800XL. My 800 has impeccable video -- unlikely to try to "fix it." 600 XL's are a different story -- ugly at the very best here.

-Larry

 

It should work the same with any Atari 8-bit, it connects to the LUMA/CSYNC/COLOR outputs of the GTIA chip which is common to all except the early CTIA 400/800. It would probably be harder to install inside the RF shield of the 400/800 systems.

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  • 2 months later...

Has anyone put one of these boards in a 600XL or a 1200XL or even a 130XE? If put into a 600XL, does it replace the missing video components?

 

I'm interested in this, but really would like to know how it does in other than an 800XL.

 

Ditto... and could we see some lavish illustrations of what the video quality looks like, PAL and NTSC...? :)

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Here some observations on composite video, im stuck with composite video for now mostly because few smaller CRT TV PAL have s-video input, And finding working 1702 monitors is very rare in my country.And servicing a CRT TV is less complicated that a 1702 if it needs fixing.

 

The different Atari 8-bits have diffrences in the Composite video quality, I have used Atari 130 XE and Atari 800XL and Atari XE Game system with composite video on CRT TV.

 

Worst if is the Atari 800XL, kinda blurry image, i did remove one of the resistors (well known quick fix for Atari 800xl Video) and the video then was a bit sharper.

 

Still The The Atari 800xl have in my experince the worst Composite video of these systems.

 

Then the Atari130XE composite, Its better than the 800xl, sharper and the colors looks better, but the Atari130xe seems to add a bit more artifacting to the image when using

composite so sometimes the image can look a litte to mutch "pixel noise".

 

Then the Atari XE Game system, The XEGS has in my experience the Best "out of the box" composite video image.

 

The XEGS have only Composite and RF video anyway, no s-video.

 

 

 

Still a little sharper than the 130xe, Colors looks nice and it has the less artifacting and "pixel noise", Artifacting is still there but less visible on the XEGS.

 

So for me the XEGS then is what i would prefer to use with composite video.

 

But The Atari 130xe with S-Video would be the best "out of the box" video of them all i guess.

 

I have no photos of this because that was some while ago and some of my Atari computers is packed away at the moment.

Edited by Grevle
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Sorry, not sure what went wrong there.

Just wanted to say that I tried the simple three step procedure posted previously by Faicuai. For me it worked beautifully. In fact I'm not sure how much better an NTSC signal can get. For the record, I modified a Hong Kong made rev C 800XL and ran it on a 35in. CRT HDTV. Is this the best s-video mod? Dunno, "Best" is a loaded term, what are the criteria? It gives you s-video with a minimum of effort.

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