SNES vertical line issue

[JDB]

Some of you may know about this, most of you probably don't. The issue is a vertical line that runs down the middle of the screen. This affects all SNES units to some degree. See picture (not mine):



Now before you post saying "This doesn't affect MY SNES unit!" or "I have never seen this line", hold on. I once thought the same exact thing. I had never (consciously) seen it before either. Different games show it differently and different SNES units show it differently as well, but the issue is the same: a graphics abnormality in the middle of the screen. Supposedly, some people have noticed this from the beginning of the SNES era, so bad caps are not the likely culprit. There are threads on Digit Press (or is it Digital Press? Aw who cares?) and Racketboy about this.

Here are the facts:

-Some people have a brighter vertical line, as seen in the picture.
-Most people seem to have a darker vertical line (darker than the rest of the picture)
-I have a slightly discolored vertical line that I must strain my eyes to see. For example, in the Metroid picture above, my line would appear to be *slightly* yellowish, but not darker or brighter.
-It affects rf, composite, s-video and RGB connections.
-Shows in some games more than others. Games to look at are the opening of Final Fantasy III as it scrolls down, Earthbound (which everyone has) and Super Metroid. Games like Super Mario Kart do not seem to exhibit this problem.
-All models/revisions of SNES have this to some degree, including the redesigned SNES 2/SNES Mini.
-If you have trouble seeing this, lowering the brightness all the way can help reveal it.

Any idea what could be the cause of this, why some have symptoms more severe than others and why it matters on what game is running? You guys are teh smartz. Figure this out!

Play some Sega instead.

[GohanX]

Has anyone bothered to test the same games through Emulation to make sure its a hardware issue? It probably is just makes me ponder.

I've never seen it through emulation, but I've seen it to varying degrees in half a dozen different SNES/SFC units.

Last weekend I dug my old Christmas of '92 SNES out and repaired it (broken power jack.) I plugged it up and surprisingly, it had no vertical line issue that I could detect. It's one of the very few I've seen without the problem!

[TmEE]

I cannot unsee that line anymore

[law2]

I cannot unsee that line anymore

Same here.

Anyway I just got my first SNES today as I haven't picked one during my childhood Now I will describe my encounters with the Mighty Vertical Line of Irritation.

I tested my SNES on two TVs (Phillips 29" PT**** HD Prepared 4:3 CRT & Samsung 19" T19E300BW 16:9 LED), three connections (Nintendo's shitty RF, Monster's Composite & Monster's S-video) and two games (Doom & Super Tennis). On Phillips with RF I had three awful vertical lines on blacks in Doom: red line on the left, greenish/white in the middle and blue (hard to see) on the right. When I turned on the Automap, I could see the doubled parts of the map on the red vertical line - quite funny. Philips with Composite gave the worst results with all three stripes. Monster's S-video got the best results with hard to see brighter line on the middle (two others were gone).

In Super Tennis with Phillips and S-video I had to look very, very hard to actually notice the stripe. On Samsung with RF the results were the same as on Phillips with S-video (it was as good). So my guess is Samsung should have no stripe when hooked up with S-video, but I didn't try it as I was lost in the spider's web of wires

So, my CRT was state of the art at the time of buying (it has HD). Turning off pixel doubling, turning on double refresh rate and altering the aspect ratio didn't change the behaviour of the vertical line.

[Drakon]

I fixed this a while ago. I bypassed the built in video encoder in my snes mini and tried a couple of different alternate video encoders. With the sony cxa1645 I still had the vertical bar. With the sony cxa2075 the s-video is sharper and the vertical bar completely disappeared. For the cxa2075 I'm just using the ntsc internal trap application circuit. Fin.

[SNKNostalgia]

It is an odd thing with the vertical bar. My SNES I bought in '94 core model had the bar and I noticed it even back then when play Final Fantasy 3. Then the system died after going glitchy with the video and I bought a replacement. It is also a somewhat later model and hasn't yellowed at all either. No vertical bar, at all. Got lucky as hell apparently.

[Drakon]

It is an odd thing with the vertical bar. My SNES I bought in '94 core model had the bar and I noticed it even back then when play Final Fantasy 3. Then the system died after going glitchy with the video and I bought a replacement. It is also a somewhat later model and hasn't yellowed at all either. No vertical bar, at all. Got lucky as hell apparently.

Some come with it, some without, bypassing the encoder with a cxa2075 removes it, I don't know why, but it does!

[UniversalMind]

The cxa1645 is rather old. Considering the resolution that outputs the Snes, the vertical resolution is output with progressive scan. Just compare the difference between the schematics for the cxa1645 and the cxa2075 by looking at their respective datasheets.

[Jorge Nuno]

A recent talk with Tmee suggested that it was due to RAM refresh. What happens is that the ICs halt for a moment on that spot which causes the main voltage rail to rise (due to reduced power consuption and trace resistance/inductance) When refresh ends the power drops and then resumes nominal value due to sudden current increase (as the chips resume operation)

You can see that the voltage spike/drop occurs in the middle on the video line
Yellow: video signal showing 2 lines
Blue: noise from 5V power



This is due to bad circuit design (High trace inductance/resistance due to big distances and little thickness) and less than adequate electrolytic capacitors.

14042013318.jpg

[Drakon]

Would better power decoupling caps help? A lot of people say decoupling the rgb nes ppu really helps remove jailbar interference.

[Jorge Nuno]

Yes it would

[old man]

How about a better voltage regulator, or removing the encoder off the main rail and having it connected to the regulator directly. Would those make a difference? I've read that modern voltage regulators are a lot better than they used to be.

[Drakon]

Yes it would

Man that's really awesome, thanks a lot for posting this! The sony cxa2075 handles it better and gets rid of it on my machine, I wonder why.

[ApolloBoy]

How about a better voltage regulator, or removing the encoder off the main rail and having it connected to the regulator directly. Would those make a difference? I've read that modern voltage regulators are a lot better than they used to be.

If you mean switching regulators like these, I've tried them and found that they generate a lot of interference. You could try cutting down on the interference with an inductor but as a purely drop-in replacement it doesn't really cut it.

[TmEE]

http://www.tmeeco.eu/BitShit/OneLineOfNoise.jpg
http://www.tmeeco.eu/BitShit/VerticalBarFix.jpg
http://www.tmeeco.eu/BitShit/IamNotS...arAnywhere.jpg