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


iainjh

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S-video is the highest denominator conning from the GTIA chip. Even with HDMI upscaling or conversions to VGA or RGB, it's still S-video as native.

 

I usually ignore composite as if I recall it drops quality and is not equal or more to the sum of its two parts lum and chroma)

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Are you are referring strictly to a DIY change-the-components, change-the-circuit type of mod directly on the motherboard like Clearpic 2KX* or Supervideo 2.1?

If so, I'm pretty sure the best one for the 800XL is the latest Clearpic 2KX mod still, I don't think anyone has improved upon it except the newer upgrade boards.

You can also install a composite on/off switch, or use the old RF switch for it if you are removing it ( RF-also important for eliminating interference) or just disconnect it completely which also reduces interference on the S-video.

After that, it all depends on how good your TV/monitor is at S-video or a converter box. You can do more to clean up the image, but it's 95+% clean signal at this point. Just the back ground vertical banding left, but good converter boxes reduce that a lot.

Though this is probably all old-hat to you, with 2600/7800 S-video mods under your hat.

 

*NOT the real name, I just forget what 2000 year the latest Clearpic is off the top of my head.

Edited by Gunstar
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Bryan's UAV is the best video - Composite or S-video - you're going to get out of an XL or XE computer. Grabs the signals from the GTIA, compensates for phase shifting via the tiny on-board potentiometer, and gives a nice, clean output signal.

 

The first version was good; I have two of them in various systems. The second version was better - I have three in systems now and a fourth will be in use when I build my 1088XLD. MacRorie is currently selling the Rev D.

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Gtia just needs a 75 ohm resistor and a capacitor to get pure signal, no need for anything else fancy or otherwise.

Sorry, I don't know what I read, but I somehow totally misread your post I responded too, as a question asking what is the current best s-video upgrade, instead of you making a statement about S-.video. So my entire response post above is moot anyway. After re-reading your post I responded too, I don't know what I thought I read before.

EDIT: I figured out my error; I guess I am just tired, and thought this was a new thread, reading the title as belonging to your post. :sleep:

 

even though, apparently, my knowledge is out-dated and I was wrong, with your simple fix here anyway.

Edited by Gunstar
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  • 7 months later...
On 6/2/2012 at 11:52 PM, Faicuai said:

...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).

...

 

Enjoy!

 

I tried to conduct the simple video mod on my NTSC 800XL rev."C" made in Honk Kong. It is equipped with an Ultimate U1MB. The TV is 65" Dansat.

When the other side of C54 is lifted, the screen is always back and white.

Color is possible only when the C54 is connected.

Let the picture explain it better:

Note: Connection through 4 is only possible if wire is removed and C54 is in place.

 

So, need your advice please. I thought it would be easy.?

madi

Untitled.jpg

wirer67-r68.jpg

White-Black.jpg

Fuzzy.jpg

chrome.jpg

DANSAT.jpg

Edited by Madi
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you should be using luma and chroma for s-video or l-c-a monitors...

if you are using composite monitor then use the composite signal...

or you can combine LC(svideo) with coupling caps and get your own fine tuned composite from there...

 

You television/monitor input from source menu looks to be composite only...

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6 hours ago, _The Doctor__ said:

you should be using luma and chroma for s-video or l-c-a monitors...

if you are using composite monitor then use the composite signal...

or you can combine LC(svideo) with coupling caps and get your own fine tuned composite from there...

 

You television/monitor input from source menu looks to be composite only...

Thank you for the info. I was only concentrating on the Atari side.

I understand from the above that, the TV/monitor must have the S-Video jack/outlet to receive the Chroma signal form Atari (which it failed and only showed white/black screen) ?

madi

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  • 2 months later...

I recently performed this mod on my NTSC Atari 800XL.

Great success! Fantastic picture afterwards.

Here is what I did on my Atari (see photo).

Remove C56.

Lift C54 on the right hand side. Add switch for composite/S-Video.

Add wire from bridge at R67/68 to composite pin on 5 DIN plug

697043B7-B4F0-4D3B-9165-C91B75E6B723.jpeg

A03BA73D-9F95-40F9-9D35-87CF6649062E.jpeg

Edited by slaanesh
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1 hour ago, slaanesh said:

I recently performed this mod on my NTSC Atari 800XL.

Great success! Fantastic picture afterwards.

Here is what I did on my Atari (see photo).

Remove C56.

Lift C54 on the right hand side. Add switch for composite/S-Video.

Add wire from bridge at R67/68 to composite pin on 5 DIN plug

697043B7-B4F0-4D3B-9165-C91B75E6B723.jpeg

A03BA73D-9F95-40F9-9D35-87CF6649062E.jpeg

Nice!!!

 

Looks pretty good on CRT!

 

For doing the very best you can, with the existing resources already present on 800XL (and without butchering it), this is the way to go! 

 

Cheers!

 

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The CRT is a Sony PVM - of course the moire pattern isn't present - it looks better in real life than the photo.

I put in a composite switch as I wanted artefact colours for games that use it.

Cunningly I just used the same spot where the channel switch is (after desoldering it out) so no "external" mods required at all.

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  • 11 months later...
On 10/2/2019 at 2:35 PM, Madi said:

I tried to conduct the simple video mod on my NTSC 800XL rev."C" made in Honk Kong. It is equipped with an Ultimate U1MB. The TV is 65" Dansat.

When the other side of C54 is lifted, the screen is always back and white.

Color is possible only when the C54 is connected.

Let the picture explain it better:

Note: Connection through 4 is only possible if wire is removed and C54 is in place.

 

So, need your advice please. I thought it would be easy.?

madi

 

 

 

 

 

 

 

I am trying to make the same mod and my results are the same as @Madi. Only B&W pictures.

 

My Monitor/TVs ( tried with 3 different old LCD TVs with S-video input) all have the S-Video input connector which I am using, but the color only is present if the C54 is connected. When going through the monitor Inputs, there is no specific S-Video input option, and the Atari image is shown in the AV1, which would be the same as if I am using the yellow RCA connected, instead of the S-Video. I even tried a small converter S-VIDEO -> VGA I have and the results are the same

 

The image is immensely better with the C54 connected but I don't understand what is wrong. BTW , my Atari 800xl board is a rev D (it doesn't have the C56 for example).

 

Any ideas?

 

Thanks

 

 

 

 

 

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On 12/9/2020 at 10:58 PM, pedgarcia said:

 

I am trying to make the same mod and my results are the same as @Madi. Only B&W pictures.

 

My Monitor/TVs ( tried with 3 different old LCD TVs with S-video input) all have the S-Video input connector which I am using, but the color only is present if the C54 is connected. When going through the monitor Inputs, there is no specific S-Video input option, and the Atari image is shown in the AV1, which would be the same as if I am using the yellow RCA connected, instead of the S-Video. I even tried a small converter S-VIDEO -> VGA I have and the results are the same

 

The image is immensely better with the C54 connected but I don't understand what is wrong. BTW , my Atari 800xl board is a rev D (it doesn't have the C56 for example).

 

Any ideas?

 

Thanks

 

 

 

 

 

 

Just a bit of clarity with C54:

 

C54 shares a common point for combining Chroma and Luma signals, to be delivered over the COMPOSITE video interface (NOT the s-Video). This is (at least) on Rev.C MoBos (the ones with opaque light-green PCBs ).

 

The idea here is to DISABLE this common summation point only WHILE using the S-VIDEO interface  (this will help clearly reduce the chroma-signal contamination of S-Video Luma component and also vertical bars, too, depending on your video display, cable and/or video-processor).

 

Summarizing:

 

1. When properly enabled, S-Video (or Y/C signal) has its OWN luma and chroma paths, and SHOULD NOT be affected by lifting C54 common end-point.

2. Native COMPOSITE video path output REQUIRES C54 end-point to be connected, otherwise you will get a B&W image if not.

 

What you are seeing in your end is most-likely the COMPOSITE video signal. Verify this by Connecting (independently) Composite and S-Video outputs from your Atari computer into your display set. DO NOT connect them at the same time, when testing C54.

 

Hope this helps.

 

 

 

 

 

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  • 2 years later...
On 6/2/2012 at 4:52 PM, Faicuai said:

...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

Plz help…

I've tried to do the video mod and cannot get color from the signal... I have a very sharp image but in black and white... mi board does not have C56, so I raised left leg on C54 and took a cable from junction on R76 and R68 to pin 5 on Monitor output... what can be happened? I watched a video from some guy that took off completely C54 and C55 and it works too... please give me some lights 

 I'm plugging my 800XL on a Sony Bravia 32'' LCD TV (KDL-32EX305)

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On 12/9/2020 at 7:58 PM, pedgarcia said:

I am trying to make the same mod and my results are the same as @Madi. Only B&W pictures.

 

On 3/29/2023 at 8:39 PM, Cesar said:

I've tried to do the video mod and cannot get color from the signal... I have a very sharp image but in black and white

If you are only getting B&W via S-Video, then the only thing that can mean is that you don't have a chroma signal present. And if you did have color, but it went away after taking out composite color bridge capacitor, then you were using the composite video signal as chroma which is not the way to go unless you have no easy alternative (XLs don't have an independent chroma signal wired to the A/V jack).

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On 3/30/2023 at 4:39 AM, Cesar said:

Plz help…

I've tried to do the video mod and cannot get color from the signal... I have a very sharp image but in black and white... mi board does not have C56, so I raised left leg on C54 and took a cable from junction on R76 and R68 to pin 5 on Monitor output... what can be happened? I watched a video from some guy that took off completely C54 and C55 and it works too... please give me some lights 

 I'm plugging my 800XL on a Sony Bravia 32'' LCD TV (KDL-32EX305)

always good to take some photos of your work and post the mere, someone may spot an error for you

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On 3/30/2023 at 4:39 AM, Cesar said:

Plz help…

I've tried to do the video mod and cannot get color from the signal... I have a very sharp image but in black and white... mi board does not have C56, so I raised left leg on C54 and took a cable from junction on R76 and R68 to pin 5 on Monitor output... what can be happened? I watched a video from some guy that took off completely C54 and C55 and it works too... please give me some lights 

 I'm plugging my 800XL on a Sony Bravia 32'' LCD TV (KDL-32EX305)

I do this mod all the time. :)

 

I assume you are connecting using a Din5 to S-video cable?

 

If you are not and are using an Din5 to AV composite cable and have lifted C54 then of course you will only get black and white. Reconnect C54 if you intend to stick with the Din 5 to AV composite cable.

 

I am also assuming you have a stock 800XL here by the sounds of it? (Rather than an 800XLF with the freddie chip which has chroma hooked up already).

 

Stock 800XLs didn't have Chroma hooked up at the factory in the 80's. Thus it is needed if you want to run a Din5 to S-video cable in colour. So hooking up chroma the way you have done it (joining R76 and R68 with solder, and taking a wire to the chroma pin 5 on the monitor) will give you chroma for the s-video - and thus colour. Then you can lift C54 in order to get a clearer picture when using svideo on a modern LCD. (Disconnecting C54 removes the composite interference when using Svideo on an LCD but as mentioned above you then lose colour on a composite cable. I get around this by installing a swtich so you can enable/disable C54 See here).

 

Also I always include a 100ohm 1/4w 5% carbon film resistor in the wire.

 

This is what it should look like, where you can connect to the monitor pin 5 on either the underside of the PCB at the via, or on top:

 

 

TOPSIDE: R68/R76 wire with 100ohm resistor to top side of monitor jack pin 5 (two examples in machines I hooked up last year):

 

image.thumb.png.a0922f12cdd4c40b75e0c49758aa8960.png  image.thumb.png.75795f97fe94efb7b416be98757d1fd9.png

 

 

OR

 

UNDERSIDE: The same, but just going in from the underside of the PCB which is prefered as easier to solder to the underside of the jack at the via (one example):

 

EDIT: found this one on AA, where you can see the resistor in the mix:

image.png.d62cccf5260c94f5a3345273665a59a1.png

 

 

These days I tend to mix it up and connect the wire to the R68/R76 junction thru the 100ohm resistor TOP side, then tread the wire through a pre-existing hole in the PCB, and hook up to pin 5 on the UNDER side. 

 

C56 lifting (when the resistor is present).

 

This is an optional mod that improves the picure sharpness by lifting one of the sides (I usually lift the right side) of the resistor. If it isn't present on the machine, which is often the case, then no worries. (Not to be confused with lifting the C54 as detailed earlier).

 

***

 

EDIT: Bottom line - it's alway good to clarify which video cable you are using to connect. Given you are posting in this thread it is assumed you are using a din5 to Svideo, but the issues you are having makes me think you are hooking up using the Din5 to AV composite. Either that or you haven't wired to the correct monitor jack pin when attempting to hook up Chroma.

 

As mino suggests upload a pic of the top and bottom sides of the PCB and we can take a look also.

 

 

Edited by Beeblebrox
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