A diagonal noise pattern appearing and disappearing in intervals

[JaCkBoston]

Issue: There's a diagonal pattern of noise waving through the screen. I've since managed to somewhat mitigate it by getting a crappy power supply out of the chain but I still get it nonetheless although in lesser quantity and only through component. Through RGB SCART the picture is clean and lacks any kind of interference whatsoever.

Here's an example on a screenshot:

How to replicate: connect a 480i source through component input. Tested with different presets, including 480p/576p, it is not preset-dependant. Tested with an HDMI converter and straight into a VGA monitor through a known good cable - results are the same.

The modifications of the board include all the recommended ones + a deprecated shielding fix with foil. I thought about replacing C33 and C35 since the issue shows in component only but may want to hold off on that until it is confirmed or denied that it's an issue with them.

I don't have a multimeter on-hand to test the power supply. When I just bought it the seller tested it with his multimeter, it was showing a stable 5V, however since then, I added an inline switch to it. Could that somehow affect the performance if it was designed for higher current operation than at 5V 2A?

Edit: replaced C33 and C35, put an inductor between Vin and P9, and changed PSU to the one that provides constant 5V(4.99 to be specific according to my multimeter). There's still noise but I started thinking that it's actually not the GBS's fault. I use a PS2 with it and play backups from my network drive through SMB. Whenever there's heavy asset streaming (like say, an FMV playing that needs constant data stream) I get this pattern. Whenever I sit in the menus or the game has loaded up, there's no pattern appearing and the picture is clean apart from regular background noise.

[goutsune]

When using PS2/PSX as source make sure it is not leaking composite signal anywhere near component Y or actual sync. I used to supply composite output signal directly into gbs board's csync and had exactly same pattern.

External sync stripper fixes that. It also might be possible to filter video signal noise with some passive filter on composite output but without proper measurement I have failed that so far.

[ramapcsx2]

We would need some serious help for this topic: It's not enough to have a scope and a vague idea what to probe, this is a topic for an experienced analog engineer :p

[goutsune]

Actually, a second workaround I found was connecting sync signal to the ground through potentiometer. Then, playing around with handle I managed to minimize diagonal noise while keeping sync detectible :P

[UnknownMartin]

Sorry for the bump, but this is a pretty huge find! I've been dealing with it, thinking it was just my GBS-8200 board being of the "cheaper" kind (yellow buttons version). If you don't mind, could you show a picture on how you did it? Still a novice when it comes to soldering and the like, so any help would be greatly appreciated!

Quick edit: I should probably mention, this scrolling noise issue looks exactly like your example. However, not only does this happen with my YpBpR video, but also my RGB video. I am able to do 960p and 720p mostly fine with nearly invisible diagonal noise (it may be viewable if your eyes are directly on the screen), but the moment I try 1080p, them lines be scrolling XD. It does sometimes go away, but as you said, it shows up again and again. I've done all the recommended noise fixes as well (c11 replacement with Electrolytic Cap, the various capacitor additions around the board, etc...) Again, sorry for the sudden bump, but I hope I can also tribute to making this incredible project better for others (and myself I guess lol)

[JaCkBoston]

Hey there, not exactly the person who came up with the fix (which I didn't try in the end, btw), but I'd like to chime in with my two cents.

I wasn't using the best component cables at the time I assembled my GBS unit and submitted this issue, a little later, in June, I believe, I ordered a set of component cables from retrogamingcables and haven't seen much of this diagonal pattern since. It looks like a lack of proper shielding somewhere along the chain or more specifically in its very beginning (on the PS AV connector) causes the EMI from surrounding electronics to bleed into the picture.

That's just a guess, but it seems to agree with observations and makes total sense to me personally, but again, take this with a grain of salt. If you're already using cables from RGC or HDRetrovision, then the problem is deeper than just bad cables.

Check your cables, people, that's what I learn for the ump-teenth time while doing something with analog hardware.

[ramapcsx2]

There can be many things that all interact and eventually produce visible patterned noise. Reduce the factors, and you reduce the chance of running into them. Good cables (in and out!) are a good start :)

[UnknownMartin]

Thanks again y'all for the tip. Unfortunately, I have been using highly recommended cables such as HD Retrovision Component Cables for my PS2, OEM Xbox Component Cables, and various RGB SCART cables from the likes of RetroGamingCables or various made-to-order ones from reputable online vendors for my remaining retro consoles such as the Dreamcast. Only exception being my Sega Saturn SCART cable which is a cheap-o one until further notice lol. So, it likely is not my cables affecting the signal unfortunately. I also can't fault my various switchers, as this even happens when I directly plug in a single console into my GBS board without anything in between. The only solution for me is to just never touch the 1080p as 960p looks amazing already and is without any visual noise that my eyes can perceive. It's just a little unfortunate for my "testing-hunger" needs, but I can definitely live without it until I decide to invest into the more-expensive scalers in the future. (Looking at you, Retrotink 5x)

It could likely be that my GBS 8200 board is the yellow button V5 board, whereas most on the forum suggest looking for the V4.0 board with black buttons. I think it was stated that there are less components used on the V5 which in turn the signal not as clean as the V4 boards? I may try my hand on creating another one again, but I'll have see if I trust my clunky hands at soldering a 2nd board ._.

Again, thanks y'all for your help and pointers! I'll try looking more into it.

[UnknownMartin]

Hello again! I completed my second GBS-Control board using a V4.0 board and did all the mods as recommended. Great news, the noise is gone! No longer do I see horizontal lines scrolling when using 1080p. Super happy about this! As for my original GBS-C, guess I could use it for when I want to play elsewhere, like a friend's house or just in a different T.V. away from my room lol.

Lesson learned: GBS 8200 V4 (non-yellow buttons) are the superior boards! :D