NESRGB Brightness issue

[Speedy]

I've been working with Mobius on an issue I’m having with my NES (AV Famicom) that he modded for me a couple weeks ago. I had a NESRGB v2 board installed in my NES and it works great aside from an issue I’m having with brightness.

Here’s an image of the end of Level 1 of SMB3 on my NES (the room is pitch black). There’s a weird increase of brightness on the edge of the screen and this is only happening with the NES:


And here’s picture of that same scene on my SNES not exhibiting the same issue:


Both consoles are using the same Retro Access cable and are connected directly to the same Sony BVM-D20F1U monitor.

Does anyone have thoughts or experience on what might be causing this?

Thank you!

[fernan1234]

I had pretty much the same issue of those brightness streaks with the same monitor model. I wonder if this could be specific to the BVMs, or more specifically the D-series.

On my Famicom + D20 this was significantly less pronounced though, and much more noticeable on the left side. In your picture you can also see some greenish/purplish vertical lines on the left side too, which mine also had.

When I switched from a D20 to a widescreen monitor (D24), it looks as if the brightness streaks were all compressed to a much thinner line on the sides, while the green line was moved outside the 4:3 raster. Here are some pictures of the brightness at the edges (other things visible are reflections or the CRT's glow):

Spoiler

This is the green line now outside the 4:3 raster (in composite since it was easier to capture that way):

Spoiler

Notice though that this only seems to happen when there's a bright overscan area. See in contrast:

Spoiler

This may mean that with the NESRGB bright scan lines close to the horizontal edges are bleeding into dark areas. It may also vary in severity by installation or monitor. Hopefully these can serve as hints for the more technical people here to figure out.

[FBX]

It's the monitor. Someone else had posted a topic about this, and it was the same monitor. Something about the overscan area echoing back onto the screen on those monitors.

[fernan1234]

That's what I thought too, but it's also unique to the NESRGB's interaction with these monitors though. No other system's bright overscan areas on the same monitor had a similar effect (that I noticed at least, then again not a lot of systems have such overscan areas).

I forgot what it looked like with a non-modded console outputting composite. That would help confirm if it's all on the monitor or if there's something unique also about the NESRGB (or NES) output.

[Kez]

Can confirm it happens on my NESRGB+D20 as well.

[Speedy]

Does anyone know if this only happens with the NESRGB? Is it possible that this isn't an issue with the BVM D-series and that it is actually a problem with NESRGB board and how the BVM D-series handles its signal?

[the Goat]

I installed an NESRGB in an AV Famicom and tested it on my BVM-D32. I didn't notice any issues like people are reporting.

[fernan1234]

I installed an NESRGB in an AV Famicom and tested it on my BVM-D32. I didn't notice any issues like people are reporting.

The D32 should be the same as the D24, on which it is much more subtle but still visible as shown in the pictures I posted. I took the pictures adjusting the exposure so that makes it more obvious than it is in normal viewing though. I basically never notice it in regular use. Since it only appears in specific circumstances (black background with bright overscan area) it's almost a nonissue on the widescreen monitors. It's a significant problem on the 4:3 monitors.

[thebigcheese]

I've noticed similar things with my NES on a PVM as well. As FBX said, pretty sure it's just bleed, essentially, from off-screen elements. For me, it's mostly noticeable on the intro cutscene for Ninja Gaiden. Think that's just the way it is. Doesn't happen when I run it via OSSC to my HDTV, so it can't be something the NESRGB is doing.

[Speedy]

Do consumer aperture-grill style CRTs not do this?

Would it be possible for Tim to implement a setting to cut-off borders automatically like what Analogue has done with the Super NT & Mega SG?

Only further confirming that this is related to the bright border overscanning, then reflecting, and causing this issue... I just noticed that this doesn’t happen when I underscan the picture:

Spoiler

[Fudoh]

Does shifting the image left and right affect this in any way?

I've seen similar effects when chaining various processors or interfaces. On certain image positions I had similar effects on the edges, but shifting the image solved this for me. In the end I just shifted the signal externally (using an extron interface) and then shifted it back on the monitor.

If you shift the image on an external interface, it basically alters the signal timing by in-/decreasing the front and back porch width. And you can then counter the shifted image by adjusting the picture position on the BVM itself.

Worth a try!

[Speedy]

Does shifting the image left and right affect this in any way?

I've seen similar effects when chaining various processors or interfaces. On certain image positions I had similar effects on the edges, but shifting the image solved this for me. In the end I just shifted the signal externally (using an extron interface) and then shifted it back on the monitor.

If you shift the image on an external interface, it basically alters the signal timing by in-/decreasing the front and back porch width. And you can then counter the shifted image by adjusting the picture position on the BVM itself.

Worth a try!

Fudoh, I can’t try this because my current Extron RGB 192v doesn’t have this capability, but I will try this with a used Extron RGB 203 Rxi that I picked up on eBay a few days ago (hasn’t arrived yet).

...regardless, I don’t think that is what’s happening here based on mine and everyone else’s experiences. Although, I’d change my mind if the NESRGB doesn’t do this over Composite, S-Video, or Component... one more thing to try

[fernan1234]

Although, I’d change my mind if the NESRGB doesn’t do this over Composite, S-Video, or Component... one more thing to try

It happens on all of those. Well I never tested component myself but I don't see why it would be any different.

The external decentering and monitor recentering sounds like an interesting idea to try out.

[Speedy]

Has anyone here tried adjusting the H BLK setting as described in this post: https://www.reddit.com/r/crtgaming/comm ... of_issues/

[Kez]

Has anyone here tried adjusting the H BLK setting as described in this post: https://www.reddit.com/r/crtgaming/comm ... of_issues/

Nice find, I just tried that and it cleared up almost completely. Still a faint afterglow at the high contrast border but none of the weird stripes.

EDIT: Quick picture, the glow is a lot less pronounced in real life.

[fernan1234]

I checked this setting on the D24's E Board menu, where there's actually two settings: H BLK LEFT and H BLK RIGHT. Adjusting both accordingly removes the overscan area and thus also the brightness bleed completely:

Before:



After:




The problem though is that this cannot be a permanent setting, since other sources with a wider viewable area will have part of it cropped away. But if you're going to be doing a lot of NES playing on a game where this is apparent, it's not a big deal to go in there and temporarily change the settings. Just make a record of the prior one.