Atari 8bit Y/C (S-Video) Issues with Various LCD Monitors

[bkamen]

I haven't started digging into this deeply yet, but I thought I'd ask here to see if there's additional information in someone's brain out there..

 

(I search the forum and haven't found anything particularly similar to my problem... so here goes)

 

I have both an Atari 800 and 130xe.

 

In days of old, I used to use a Thompson monitor that had Y/C inputs on it. T'was fabulous. That monitor is long gone.

 

These days, I have (2) Samsung 150MP's (15" LCD's w/both Y/C & Composite Inputs) and a 710MP (same deal, but 17" LCD).

All the Samsungs are from the days of analog TV, so they even have analog tuners in them (haven't tried that though).

 

I also have an Epson EMP-S4 projector and a Toshiba 42" HDTV.

 

I also have (for fun) a Happuage NTSC (Y/C & Composite) ->USB video digitizer.

 

I've tried the 130Xe in both composite and Y/C mode on the Hauppage as well as Samsung and Toshiba sets and the video looks like crap to unreadable.

 

The Epson Projector? Looks AWESOME. (has like a 30ft cable through the ceiling run to it.)

 

The Atari800 also looks like dirt on the Samsungs/Hauppage as well.

 

I have a MythTV system I used for S-Video to the projector normally. It looks swell -- but on the samsungs looks "mehM.. (not unviewable, but there's definitely noise) - that same signal looks fabulous on the Happuage digitizer.

 

So you can see where I'm going. Between (2) Atari's that seem to be working fine and a handful of displays, the results are wide and varied.

 

I'm going to get some scope shots up of the Atari output signals at some point..but in the meantime, I thought I'd ask folks if they had similar issues with monitors where your source looks great on one set, but lousy on another -- and if you managed to determine why.

 

Thanks,

 

-Ben

[bkamen]

here's the composite out of the 130XE and 800 loaded with 50ohms

(it's what's on the scope -- better than x10 probe but looks about the same)

 

The Vsync is 59.925Hz and the HSync is 15.725KHz, Vpeak is about 900mV

 

 

On the 800, the Vsync & HSync are essentially the same, Vpeak is about 600mV with the SuperSalt cartridge plugged in.

 

There's a little more over/undershoot with the 130xe... but they look pretty good.

[bkamen]

Well, I think I've figured out the problem... and it's 2 fold...

 

1: The Atari does not put out both fields. Only field 1.

2: The Atari doesn't look to have standard sync pulses which are space at 2x Hsync rate (31.5KHz)

 

(see the attached) -- I can see why a standard strict NTSC Video Decoder would be unhappy with this.

 

Hopefully this helps others...

[Andromeda Stardust]

I am having a similar problem with getting a video capture card to work with an Atari VCS. I am using an old busted VCR as an RF demoulator. If I plug the yellow cable sticking out of the VCR into my 2001 CRT TV set, the colors are flawless. If I plug the yellow composite cable into the Hauppauge USB capture device into my PC, the resulting video is a roach quality grayscale mess. Here is a sample of NTSC video captured from my 4-switcher Atari. the composite out from the VCR displays flawlessly on my CRT TV set, but my capture card doesn't like it at all for some reason. I've also used the same capture card for later video game consoles like the NES, which recorded the colors flawlessly.

http://www.youtube.com/watch?v=HF25v7LL5m8

 

Read the thread here:

http://www.atariage.com/forums/topic/201952-hauppauge-usb-video-capture-device-doesnt-like-my-ntsc-atari-vcs/

Edited August 25, 2012 by stardust4ever

[+bob1200xl]

Yep... the Atari does not put out odd/even frames. Old analog circuits would not care; new digital circuits may. (or, may not)

 

I don't see why the double-sync would be necessary. Only higher definition frames would have them - 480i stuff like an Atari should be OK.

 

All of my LCDs work on the Atari when I use Composite. A few of them don't work with Y/C, but I pretty much just get a blank screen rather than garbage.

 

We could fix all this by decoding the Atari back to digital, filling a frame buffer, and encoding the data back to something more useful, like VGA or 720p.

 

Bob