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tzakiel
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Horizontal dark/light lines on backgrounds

by tzakiel Thu Aug 10, 2017 1:39 pm

I have noticed this same problem with my SNES, NES, Saturn, and Genesis consoles on a variety of different TVs (tried both LCD and CRT tvs) and it's driving me nuts. Any idea what causes this?

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I'm having a lot of trouble understanding what causes this. It appears dark like this if you have a dark line (like between the bricks in the screenshot) across some of the screen with a brighter background next to it. And it does the opposite if you have a bright object on a dark background (the streak is then lighter than the background, and still extends across to the right). If the object is moving, the streak follow it up or down the screen to the right side.

Here's what I've tried to rule out:

Consoles: 4 consoles do it, so I doubt it's some issue with 1 console's caps or whatever. I guess it's possible I have 4 bad consoles or that all consoles do this and I am just sensitive to it, but unlikely?

TV: I've tried 3 TVs, one of which is a brand new LCD

Cables: I am using SCART RGB cables for all of these, with a framemeister or direct to my PVM CRT. One of them is a different brand than the others. I also tried an s-video cable to a couple of TVs and it did the same thing. I have not tried a truly grounded and shielded SCART cable yet, like the packapunch, but it seems unlikely that all these cables are bad and cause the exact same issue to the same degree.

Power: I tried running the console off a UPS battery power supply to isolate it from the wall. Granted the display was still plugged into the wall.

I'd really like to at least understand what causes this, so I can use that to look for a fix.
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Sarge
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Re: Horizontal dark/light lines on backgrounds

by Sarge Thu Aug 10, 2017 3:00 pm

I don't think that's a console issue, it's either display or cable related. Are they there when the screen is static, or do they only appear while in motion? It wouldn't surprise me if it's just artifacting that's inherently there and just not noticeable with duller displays.
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tzakiel
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Re: Horizontal dark/light lines on backgrounds

by tzakiel Thu Aug 10, 2017 3:14 pm

Sarge wrote:I don't think that's a console issue, it's either display or cable related. Are they there when the screen is static, or do they only appear while in motion? It wouldn't surprise me if it's just artifacting that's inherently there and just not noticeable with duller displays.


They appear either when static or in motion. In the example screenshot I posted its a still screen. However if that floor moved up or down the lines next to it would follow.
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marurun
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Re: Horizontal dark/light lines on backgrounds

by marurun Thu Aug 10, 2017 3:17 pm

Analog signals based on scanlines will always have some level of artifacting. Hard to know if that particular artifacting is something you can adjust. Do you run the consoles directly to the screen or through some kind of AV switch or receiver? Look for a common element wherever possible.
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tzakiel
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Re: Horizontal dark/light lines on backgrounds

by tzakiel Thu Aug 10, 2017 5:56 pm

marurun wrote:Analog signals based on scanlines will always have some level of artifacting. Hard to know if that particular artifacting is something you can adjust. Do you run the consoles directly to the screen or through some kind of AV switch or receiver? Look for a common element wherever possible.


I've tried various cables directly to various tvs. Composite and rgb cables to a tv or to framemeister and then to LCD screens. I've tried direct to pvm crt and direct to composite LCD
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Anapan
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Re: Horizontal dark/light lines on backgrounds

by Anapan Fri Dec 08, 2017 2:55 am

I saw a youtube video about this problem a week or so ago - I think it was from RetroRGB - maybe from that gameboy video perfection thing?
The problem talked about was actually caused by the motherboard layout of the console and lack of shielding or distance between components. The solution that was shown involved cutting traces coming from the video chip and rerouting them with kynar wire to bypass the interference.
This solution is far beyond my capabilities - tho seriously impressive.
Jinn nearly eliminated some harsh jailbar interference that was present on my RGB AV famicom during the mod by applying some thick copper tape to a couple of ICs in the replacement (PC10) video processor area. That is an easy fix you should try - just be careful not to short any exposed IC legs with the metal tape.
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tzakiel
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Re: Horizontal dark/light lines on backgrounds

by tzakiel Fri Dec 08, 2017 4:29 am

Actually it was a confirmed defect with the 2017 nes rgb boards. Fixed with a filter cap.
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Anapan
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Re: Horizontal dark/light lines on backgrounds

by Anapan Fri Dec 08, 2017 7:14 am

This was a PC10 PPU replacement, not NESRGB, but it does seem to be an onboard capacitor problem.
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Anapan
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Re: Horizontal dark/light lines on backgrounds

by Anapan Fri Dec 22, 2017 8:22 am

Fix!
https://youtu.be/gvliOHNfCAA?t=569
It is a capacitor problem, and for 1-chip SNES at least, the problem has a solution.
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