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s-video mod 9 vertical lines on left side


grips03

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I have s-video mod and I get 9 vertical lines on the left side of screen, right side is ok. The vertical lines are equally spaced. System is Atari 5200 4-port with power mod. I should also note my 2-port Atari 5200 also has the same issue, they both have the same type of s-video board. Best way to see the vertical lines is with Moon Patrol all blue screen, or if you wait long enough it will show a red screen and its even easier to see there.

 

What I have tried so far to fix:

 

1-shielded video cable between mod board and connectors = no change

2-different s-video cables (3) = no change

3-Removed 2 inches of wire from mod board to video IC, i.e. mod board now sits directly on the video IC pins = no change

4-Used another 5200 power adapter = no change

5-HP bench power supply = no change

6-HP bench power off UPS = no change

7-Adjust R8 - you can make the 9 vertical lines appear less if you adjust, but they are still there, i.e. you might make them mostly disappear on blue screen, but they will show up on red screen

8-Lines are still present with composite cable

9-Removed RF module = no change

 

Any other ideas to try?

post-27883-0-97435000-1383491900_thumb.jpg

Edited by grips03
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vertical lines do not appear on 25" and 36" Sony CRT TVs. Vertical lines show up on Sony 52" LCD "W" model

 

I switched to Atari 7800 and I still see the lines. Looks like 5200 might not be to blame. Going to upscale s-video to hdmi and see if issue remains.

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You could try a capacitor (in the pF or maybe low nF range?) from the signal to ground, to see if that helps. Too big of a capacitor and the display won't be as sharp.

 

I tried 4.7pf and it was the same. I then switched to 1nf and it had vertical banding (I think that is the name for it).

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I tested with Micomsoft XRGB mini Framemeister tonight and the 9 vertical lines are still present. I think this is just how the s-video mod works. Its still better than RF.

 

XRGB mini settings:

IMAGE_MODE = Standard - has low pass filter, helps clear up vertical lines, they are still there but reduced

SCREEN_SET = Standard

HDMI_OUTPUT= 480_60p

Edited by grips03
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If you have some spare 1uf or 10uf caps, place a couple in parallel with the existing ceramic bypass caps connected to the system RAM. Just add a couple and see if they begin to diminish the effect.

 

Is the system ram the 8 chips is a row on the left? I see some small bypass caps (blue in color, 104s I think), you mean those?

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These would be the little .1uf caps on the right side of the RAMs. C26, C139, etc. I've done the S-Video mod before and added electrolytics in parallel with these to diminish the lines.

 

With it running, you should be able to just touch an electrolytic cap to the existing ceramic and see an immediate change.

 

Also check that your ANTIC, S-video circuit, and S-video connector grounds are at the same potential. I try to ground & power my circuit directly from ANTIC to keep any ground loop issues at bay.

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The ceramics could be on the left too, I'm referencing a 4-port board myself. Not sure if they are in the same position on the 2-port boards or not. If in doubt, check the schematics :)

i have 4 port as well.

 

I added qty 8 10uf cap in parallel, on c26, c139, c25, c27, c121, c28, c138, c29. This did not change much. I then switched to .1uf and got similar results.

 

now if I paused the 5200 the 9 vertical lines when mostly away

 

Perhaps I need to remove the caps on the motherboard vs. adding in parallel?

 

I'm powering the s-video board from gnd (pin 1) and +5 (pin 21) on the ANTIC

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I hate to recommend a shotgun approach, but all the chips could probably use bigger bypass caps. Haven't tried this myself but it has cured similar problems with other consoles.

 

I don't know how pause is implemented programmaticly, but if it puts ANTIC in a lower power mode, that could be why the refresh lines disappear. E.g. the chip consumes less power and the +5v becomes more stable.

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Maybe the CPU draws less power when paused, you know, that's just the theory I'm working on. That the lines become visible during higher power consumption because there is a lack of reserve capacity current-wise off of the regulators. I will try to get some measurements over t'giving break. What game do you observe the pause phenomena with?

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Maybe the CPU draws less power when paused, you know, that's just the theory I'm working on. That the lines become visible during higher power consumption because there is a lack of reserve capacity current-wise off of the regulators. I will try to get some measurements over t'giving break. What game do you observe the pause phenomena with?

 

Moon Patrol is the game I'm testing with

 

What size caps should I use to replace the 104s?

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