Video probs w/ SNES RGB (Vertical Bands, etc)

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Voultar
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Voultar »

Great shots, FBX!

I think this is going to be a balancing act between C11 and R3. It's the marriage between these, that's probably going to be the key.
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FBX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by FBX »

Just tested the APU revision, and there's no funny stuff with the top lines of graphics. This means these Capcom games are another in the list of compatibility issues with the 1CHIP revisions. The change of capacitance on C11 merely enhances a glitch that is already there (as others have pointed out with the stock C11 cap still showing a small amount of the glitch).

Edit: My apologies, I've been up the past two days and didn't realize I was swapping terms in my posts. I've gone back and made the corrections.
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ikari_01
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by ikari_01 »

Nice, that's exactly the thing that causes the sync glitch in Rudra's Treasure where they change screen brightness ($2100) mid-screen. As soon as brightness is changed from 15 to 1, the image output becomes a solid grey (presumably the virtual GND of the DAC or something similar) that needs some time to recover. It appears that on the S-CPUN they implemented the screen brightness register by changing the DAC gain directly but that's just speculation on my part.
The larger C11, the longer it takes to recover, as is nicely shown in FBX's shots. The sync glitch occurs because it also affects composite video output such that it gets shifted up by 0.5V or so, totally garbling the sync.
Unfortunately for Rudra's Treasure that means it turns a slightly shifted scanline into a flickering mess :)

I believe it is the same cause that makes the shadow appear too bright in Air Strike Patrol.
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Voultar
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Voultar »

RGBSource wrote:
So, if people are using Voultar's board, they should probably be removing the 1k2 resistors on that PCB and replacing R3 with the appropriate value on the console PCB (and adding a series cap before the THS7374).

I know RGBSource/32E/insert trolling name was banned, but I missed his suggestion of adding "series caps" to the inputs of my PCB. Probably just to troll, but I'll address it.

How much DC offset is there off the DAC outputs on the 1CHIP? Maybe a couple of mV, at the most. There's no reason to couple the inputs as the negligible DC offset is well within the operational limits of these drivers.

Image

^ The 1CHIP DAC does drive to 0V. As I explained earlier that it's a current steering DAC design.

Does it hurt adding them? Absolutely not. Is it worth adding them? Not really.

That's all. Carry on, guys/gals!
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otj
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by otj »

Here's a funny story and a question for you folks.

I arrived home from work last night to discover a package from Digi-Key containing my 0.47UF 16V X7R 0603 caps for C11. Despite being tired from working all day, I was pretty excited and launched into performing the swap right away. In hindsight, I probably should have waited until I was well-rested.

I looked right at C11, went to remove C11, and removed C1 instead. Brilliant! To make matters worse, because I didn't realize my mistake right away, I can't find the cap I removed. :oops:

On the plus side, the actual C11 cap went in smoothly and looks great. :roll:

So, does anyone know the value for C1 on a SNES mini/jr? I'd hate to guess and cause the magic smoke to come out.
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FBX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by FBX »

otj wrote:
So, does anyone know the value for C1 on a SNES mini/jr? I'd hate to guess and cause the magic smoke to come out.
Damn, sorry nobody got back to you on this. I pulled it and measured 18nF for the stock cap.
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otj
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by otj »

FBX wrote: Damn, sorry nobody got back to you on this. I pulled it and measured 18nF for the stock cap.
No worries, and huge thanks for the help. I definitely owe you one.
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Link83
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Link83 »

So I just wanted to check, is replacing C11 with a 470nf capacitor now the best way to fix the ghosting on 1CHIP systems, despite the missing lines on some Capcom games? Or does the 20ohm resistor on CPUN pin 155 method work better with less issues?

Also, after replacing C11 are 1.2k/750ohm resistors on the RGB lines still necessary? Or is the brightness also corrected?

Lastly, does replacing C11 fix the 'white bar' issue, or is that unrelated?
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FBX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by FBX »

Link83 wrote:Also, after replacing C11 are 1.2k/750ohm resistors on the RGB lines still necessary? Or is the brightness also corrected?
The C11 cap upgrade doesn't help RGB line attenuation, so you'll still need corrective measures for that.
Lastly, does replacing C11 fix the 'white bar' issue, or is that unrelated?
Unrelated. The best fix for that bar is to upgrade the voltage regulator and cap (typically C61) associated with it.
thebigcheese
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by thebigcheese »

I know this thread is kinda old at this point, but thanks for going through all this hassle. Ordered some caps for C11 today. I noticed a weird ghosting on some game or another and thought it was just something weird with my TV, but nice to know that a) I'm not crazy and b) it's not an issue with my PVM. Thanks!
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Akira
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Akira »

I also want to chip in to thank you all for your research on this. I read through all 8 pages of fascinating discovery.
One question, can this modification be applied to the older snes/sfc models? I don't have a 1chip model, mine is a SNS-CPU-RGB-01
I bet the answer is "no" but I thought I'd try, since I hate all that ghosting. I read some mentions of other revisions being tested, but I am not savvy to all revision of SNES/SFC so I got lost.
.:[ BLAST OFF AND STRIKE THE EVIL BYDO EMPIRE! ]:.
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AndehX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by AndehX »

FBX wrote:Unrelated. The best fix for that bar is to upgrade the voltage regulator and cap (typically C61) associated with it.
upgrade to what? Or do you mean replace with a newer 7805?
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FBX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by FBX »

AndehX wrote:
FBX wrote:Unrelated. The best fix for that bar is to upgrade the voltage regulator and cap (typically C61) associated with it.
upgrade to what? Or do you mean replace with a newer 7805?
Upgrade 7805 to 78s05 I believe it is.
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mikejmoffitt
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by mikejmoffitt »

You may also have good luck replacing the 7805 with a compatible drop-in switching voltage regulator. I have done that for a number of my consoles early on (I think one by EZSBC?) and the results have been great. No white bar on my SFC.
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rama
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by rama »

Note: The biggest effect on that vertical bar is from adding a good chunk of capacitance right at the 7805.
It doesn't actually matter that it's close to the regulator, but this is a good location to place a huge can.
Use 1000uF low ESR (minimum 6.3V).

Doing that simple mod reduces the bar to a level you can only spot in with a good upscaler and on the worst possible backgrounds.
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AndehX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by AndehX »

I have a 470uf cap on my SNES and I can't see the vertical bar at all on my capture card
paulb_nl
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by paulb_nl »

Thanks to the captures by FBX of the different capacitor values I replaced my 470nF C11 with a 220nF one. With that cap only the first line is darkened with Street fighter instead of 3 lines. The ghosting is greatly reduced compared to 47nF and comparing captures I couldn't see a difference between 220nF and 470nF even with gamma extremely lowered.

The dark lines at the top happen with games that turn the display register on mid-frame. Other games I found with the same issue are: Starfox, Stunt race FX, Cybernator (some parts) and Super Mario 3 in All-stars (item box).
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FBX
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by FBX »

paulb_nl wrote:Thanks to the captures by FBX of the different capacitor values I replaced my 470nF C11 with a 220nF one. With that cap only the first line is darkened with Street fighter instead of 3 lines. The ghosting is greatly reduced compared to 47nF and comparing captures I couldn't see a difference between 220nF and 470nF even with gamma extremely lowered.

The dark lines at the top happen with games that turn the display register on mid-frame. Other games I found with the same issue are: Starfox, Stunt race FX, Cybernator (some parts) and Super Mario 3 in All-stars (item box).
Cool thanks for the heads up on those other games. I was a stickler for '100%' ghost removal, so I stayed with the 470nF cap. Granted, I was using an OSSC and testing negative images at oversharpened levels, but I had to be sure.
copy
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by copy »

Voultar wrote:Great shots, FBX!

I think this is going to be a balancing act between C11 and R3. It's the marriage between these, that's probably going to be the key.
Voultar, have you had any luck finding this balance? I know you're a busy man.
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Syntax
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Syntax »

There is no balance.

You replace R3 instead of adding 3 resistors to RGB output to attenuate brightness.
You replace C11 to remove ghosting but it adds a black bar on some titles.

That's it.
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by copy »

I would still like to hear Voultar's latest thoughts on the idea he originally suggested, thanks.
fandangos
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by fandangos »

I believe this is not entirely related but it might be worth a shot asking.

I have a 1chip famicom that I did:
750 ohm attenuation on RGB lines.
Replaced 7805 with 78s05.
Replaced C11 with 470nF XR7 caps.

I only play on CRTs. Using direct RGB or RGB to component using the Kramer FC-14.
I modded the official nintendo jp21 cable with the resistor (don't remember at the correct value) to correct sync.

Using CSync here, modded the console to output only csync (cut trance and bridged the composite and csync pin) because I still wanted to use the official cable.

So my problem, when playing FF3 with SD2Snes, I see some waves, specially on dark scenes. It's like a "flag in the wind", but only in the background when displaying the game title. It's like waves going from bottom to top, it's hard to describe or get pictures of.

Is that fixable?
paulb_nl
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by paulb_nl »

Do you see the same waves in Star Fox if you pause the game in the first level? I see waves there with my 1-CHIP-01 but not with a 1-CHIP-02 or Snes jr.

Aladdin also has some waves in certain color backgrounds.
fandangos
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by fandangos »

paulb_nl wrote:Do you see the same waves in Star Fox if you pause the game in the first level? I see waves there with my 1-CHIP-01 but not with a 1-CHIP-02 or Snes jr.

Aladdin also has some waves in certain color backgrounds.
Have to test those. I'm away from my snes at the moment :(
rama
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by rama »

Those waves are a big topic.
Their cause can be many things, but very often it is poor power supply decoupling in one of the active devices in your chain.
It could be the console, the TV itself, in upscalers and in scan converters.

Occasionally, it is a poor ground connection in the video cables. Cleaning the console AV port should be your first step.

If that Star Fox test is positive (you get waves in that game, but not in most others), then it points to the SNES.
Does the SNES have extra bypass capacitance? I like to populate the OSCON spot with a 470uF low ESR electrolytic.
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James-F
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by James-F »

Can someone please take a photo of the region where R3 is.
borti4938

Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by borti4938 »

It’s next to C11. Look at Voultars post about his C11 find: viewtopic.php?p=1282757#p1282757
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Link83
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Link83 »

So just to make sure I understood correctly, for a stock 1CHIP I would need to:-

Replace C11 with a 220nF capacitor - To reduce ghosting, whilst also only darkening the first line on certain games.
Replace R3 with 1.74kohm resistor - To attenuate brightness
Replace 7805 and C61 - to remove vertical white bar (If present)

Is that all the mods required to 'perfect' the 1CHIP's video output?

I would also be curious to know if the 'S-RGB' and 'S-RGB A' video encoders require a different value for R3?
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James-F
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by James-F »

Are the Composite and S-Video outputs on the 1chip (from S-RGB/A) too bright too?
In other words, by adding 1.2k/750 on the 1chip do Composite and S-Video become too dark?
My goal is to maintain correct levels on all analog outputs of the 1chip.
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Syntax
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Re: Video probs w/ SNES RGB (Vertical Bands, etc)

Post by Syntax »

James-F wrote:Are the Composite and S-Video outputs on the 1chip (from S-RGB/A) too bright too?
In other words, by adding 1.2k/750 on the 1chip do Composite and S-Video become too dark?
My goal is to maintain correct levels on all analog outputs of the 1chip.
As I read this I thought you were asking if R3 replacement lowered the already correct svideo, comp video brightness levels.
I personally never properly checked what the comp video output looks like as I just use it for sync.
And im not sure how many other have replaced R3. Borti?

You shouldnt have to touch the comp or svideo outputs on any SNES im pretty sure.
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