Screen "Quivers" Occasionally?

[hizzy]

Hi Atari Gurus!

 

I have an s-video modded atari which I recently hooked up to a new-ish HD TV. I'm having great fun with it and the picture looks great but, every so often, the screen quivers or slightly shakes up and down. It's a very slight movement. What causes this? Is it the TV? Is there something wrong with my mod? Is this what is called "screen roll"? Thanks in advance for your help!!!!

 

[hizzy]

I tried an unmodded 7800 with an RF connection into my new-ish HD TV. Guess what? No shaking at all! A rock solid picture. I wonder what causes the shake/shimmy/hop on the modded 2600?

[+Andrew Davie]

10 hours ago, hizzy said:

I tried an unmodded 7800 with an RF connection into my new-ish HD TV. Guess what? No shaking at all! A rock solid picture. I wonder what causes the shake/shimmy/hop on the modded 2600?

It can depend on the game you are playing. Some games simply don't have a stable number of scanlines.

 

[+DrVenkman]

1 hour ago, Andrew Davie said:

It can depend on the game you are playing. Some games simply don't have a stable number of scanlines.

 

Yep. And different types of TVs deal with that in more or less-graceful ways. It’s even worse if you’re using a modern digital flat-panel display with an upscaler. For instance, last week I was testing a 5200 homebrew release candidate - the title screen evidently had too many scanlines (the “display list” was too long, in A8-speak). Connected directly to my TV’s composite input, the screen rolled as if the vertical hold was messed up on an old analog TV set. Connected via HDMI through my RetroTink 2X-Pro scaler and the game wouldn’t display at all. The TV flashed an image briefly and then threw up a “Resolution Not Supported” message. 

 

So then I tried several 2600 games - Atari’s Battlezone has missed and skipped frames and is basically unplayable through the scaler, even though the image seems stable. I found out later from one of the coders here that Battlezone has some weird stuff in its game display kernel, and that can confuse modern digital TV’s the expect a rock-steady, never-changing digital frame rate. By contrast, Activision’s Starmaster simply doesn’t display at all through my RetroTink. A brief flash of the game screen and then, “Resolution Not Supported” from the TV.

 

[hizzy]

Does the RF connection deal with scanlines best? I was surprised to see no jitter or jumping with an unmodded 7800.

 

Thanks for the help!!

[+-^CrossBow^-]

13 minutes ago, hizzy said:

Does the RF connection deal with scanlines best? I was surprised to see no jitter or jumping with an unmodded 7800.

 

Thanks for the help!!

My guess is that the RF modulator itself might provide a cleaned up signal and the fact that most of the analog tuners are still able to handle these odd signals better. But this isn't true of all consoles. The Intellivision systems will all jump up and down slightly on my setup through RF in my game room, but once I put composite upgrades into them, they produce a nice stable picture. So it just depends on the console really.

 

[Video]

Different games have different scanlines, since the 2600 isn't standardized, it was up to individual games to dictate how many to use. Of course, old fully analog crt, didn't particularly care what signal is piped in (within reason) but it can cause issues if your tv doesn't like the scanline count. It can jiggle, or even outright roll the image. This is most notable on pal games (which are often higher resolution than ntsc games) being played on ntsc systems/sets.

 

Because the games themselves determine resolution, some games will switch resolutions as they play, usually between title screen and gameplay screens, but it can change resolution on the fly too, and really mess with the image the tv is expecting.

[hizzy]

57 minutes ago, -^CrossBow^- said:

My guess is that the RF modulator itself might provide a cleaned up signal and the fact that most of the analog tuners are still able to handle these odd signals better. But this isn't true of all consoles. The Intellivision systems will all jump up and down slightly on my setup through RF in my game room, but once I put composite upgrades into them, they produce a nice stable picture. So it just depends on the console really.

 

 

Do you think the same thing would happen with the UAV mod? It looks quite good!

[+-^CrossBow^-]

Yes..it would. In fact many games that look fine through RF will show the scanline issues mentioned above even more so with a UAV into a scaler like the Tink2x or Tink2x Pro. Empire Strikes Back will cause the screen to go blank for a bit when you take down the AT-ATs. Moon Patrol's title screen will usually be blank due to incorrect scanline counts on that screen but the actual game will still play fine.

 

In some cases connecting the composite output from the video upgraded system into the TV will yield better results. 

 

I have a UAV in my 7800 and hadn't even noticed these issues with the game. But I'm using an older scaler device that seems to filter these odd behaviors and so the games work fine for me or just have a slight jump in the signal when it changes but not constant.

 

@DrVenkman mentioned the issue with a homebrew game on his 5200 and he has a UAV installed in his 5200. But I have heard of similar issues being more prevalent with any of the AV mods when connected to the Tink2x and other similar devices.

 

 

 

[hizzy]

2 hours ago, -^CrossBow^- said:

Yes..it would. In fact many games that look fine through RF will show the scanline issues mentioned above even more so with a UAV into a scaler like the Tink2x or Tink2x Pro. Empire Strikes Back will cause the screen to go blank for a bit when you take down the AT-ATs. Moon Patrol's title screen will usually be blank due to incorrect scanline counts on that screen but the actual game will still play fine.

 

In some cases connecting the composite output from the video upgraded system into the TV will yield better results. 

 

I have a UAV in my 7800 and hadn't even noticed these issues with the game. But I'm using an older scaler device that seems to filter these odd behaviors and so the games work fine for me or just have a slight jump in the signal when it changes but not constant.

 

@DrVenkman mentioned the issue with a homebrew game on his 5200 and he has a UAV installed in his 5200. But I have heard of similar issues being more prevalent with any of the AV mods when connected to the Tink2x and other similar devices.

 

 

 

 

What if you use the UAV mod without a scaler? I would just plug it directly into the composite or s-video jack of the TV.

 

Thanks again!!

 

[+-^CrossBow^-]

Can't really answer there. On my TV it seems to do okay but not all TVs are the same. I can only state what others have observed or experienced. Again, I don't think the UAV will prevent those issues since it is still sending the same signal that the console is already producing, just much cleaner. The blanking issues through scalers and on some TVs isn't due to a weak signal, it is due to the contents of the signal not being within proper spec that today's TV seem to be less tolerant of as compared to older CRTs.

 

 

[+DrVenkman]

3 hours ago, hizzy said:

 

What if you use the UAV mod without a scaler? I would just plug it directly into the composite or s-video jack of the TV.

 

Thanks again!!

 

*IF* your TV has an analog composite input, you won't have the blanking issues I mentioned above, but you might still have a rolling image if, for example, the 2600 game has too many or two few scanlines compared to what the TV expects. Modern flatscreen TVs, even if they still have a composite input, still have internal digital circuitry that expects a relatively stable NTSC or PAL signal from, say, a DVD player or more modern console - a device that is designed to produce a stable, standardized number of scanlines. 2600 games just *don't* do that - each game has its own display kernel that can contain as many or as few scanlines as the programmer wants, that can place a VSYNC break anywhere in the game code the programmer puts it; etc. Old analog TVs with knobs and dials you could adjust were much more tolerate of variable signals than modern sets. 

 

Now having said all that, more and more new TV's are doing away entirely with analog inputs. My 2013 LED set in my gameroom has composite and component inputs; my 2018 4K LED TV downstairs in the living room has only 4 x HDMI ports and an ethernet connection. So for that TV, I would *have* to use an HDMI upscaler, with the possible issues discussed earlier in the thread.

[hizzy]

Just wanted to let you folks know that I found if I let my S-Video modded 2600 run with a game in it for 3 - 5 minutes, I end up with a rock solid picture going into my Samsung flat screen. I can play that game for hours without a single jump.

[+Andrew Davie]

On 6/22/2020 at 7:46 AM, DrVenkman said:

2600 games just *don't* do that - each game has its own display kernel that can contain as many or as few scanlines as the programmer wants, that can place a VSYNC break anywhere in the game code the programmer puts it; etc. Old analog TVs with knobs and dials you could adjust were much more tolerate of variable signals than modern sets. 

 

Case in point; my chess game (when thinking) doesn't form a proper TV frame at all. In fact, if you press the joystick button to see it "thinking", it creates a screen an infinite number of scanlines long. CRTVs can/do display this in a way that actually looks cool. To me, anyway. I shudder to think what a modern digital TV would make of it.

[hizzy]

Just FYI, I ordered a switch selector box I it's really helped to stabilize my picture. This is what I ordered:

 

https://www.amazon.ca/gp/product/B01LY1FZ8K/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

Why would this help? Is there anything special in a switch selector box?