An actual SNES mod to sharpen the pixels of 2-CHIP consoles?

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yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

captaineos wrote:Me again. I read the chat about blur and overshoot and later technical improvements related to the amp.
I, for one, must be lucky as I have what I consider to be a pristine image with Buttersofts PCB that I've written about earlier.
I am posting becuase I thought maybe I was over-estimating the sharpness as clearly there is some blur that people have. I went back and took this photo - edges look clean to me. The cable is custom and my PAL console has C-SYNC restored.
Full resolution photo processed from RAW with no noise reduction:
https://imgur.com/eWwmP6Y
https://imgur.com/C5SgG28
100% crop provided
[snip]
The problems with the mod become apparent as it goes under increasing levels of scrutiny. Although it might look fine on a CRT, the "lens" that you are looking through is very blurry. On the other extreme, the clearest lens is through an oscilloscope of sufficient bandwidth, where it reveals a hopelessly distorted signal :)

Personally, I'm aiming for the best appearance I can get after optimal 8-bit digitization, since the hardware is currently available to us hobbyists. In this realm, the problems with the JP mod are clear and solutions are difficult to find. However, even if it might be a fool's errand, I believe I can reach a point where it looks "good enough" for me. You found your settling point with your equipment setup and that's great too!
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BazookaBen
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by BazookaBen »

Issac Zachary wrote: I've been using S-Video on a consumer CRT and it looks pretty good to me. But when I look at RGB pics of non-modded 2 chips like mine it looks like a step down. Maybe it's just the close up effect.
Out of curiosity, last night I dug out my 2-chip SNES, and s-video really does seem sharper than RGB out. It was just a quick test in a couple games, so nobody should take my word for it.

But I'm wondering how that would happen. Maybe luma and chroma are passed through more properly tuned components than than the RGB lines?
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maxtherabbit
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by maxtherabbit »

BazookaBen wrote:
Issac Zachary wrote: I've been using S-Video on a consumer CRT and it looks pretty good to me. But when I look at RGB pics of non-modded 2 chips like mine it looks like a step down. Maybe it's just the close up effect.
Out of curiosity, last night I dug out my 2-chip SNES, and s-video really does seem sharper than RGB out. It was just a quick test in a couple games, so nobody should take my word for it.

But I'm wondering how that would happen. Maybe luma and chroma are passed through more properly tuned components than than the RGB lines?
I've recently used my SHVC-CPU-01 through both Y/C and RGB and I cannot say that I agree
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TooBeaucoup
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by TooBeaucoup »

maxtherabbit wrote:
BazookaBen wrote:
Issac Zachary wrote: I've been using S-Video on a consumer CRT and it looks pretty good to me. But when I look at RGB pics of non-modded 2 chips like mine it looks like a step down. Maybe it's just the close up effect.
Out of curiosity, last night I dug out my 2-chip SNES, and s-video really does seem sharper than RGB out. It was just a quick test in a couple games, so nobody should take my word for it.

But I'm wondering how that would happen. Maybe luma and chroma are passed through more properly tuned components than than the RGB lines?
I've recently used my SHVC-CPU-01 through both Y/C and RGB and I cannot say that I agree
My 2-chip in S-Video is noticeably sharper than its RGB output. I'm sure this varies heavily from console to console, though. Mine in RGB is a literal blur, but not so when I use S-Video. It's really weird. Mine is a GPM-02.
dajigo
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by dajigo »

TooBeaucoup wrote:
My 2-chip in S-Video is noticeably sharper than its RGB output. I'm sure this varies heavily from console to console, though. Mine in RGB is a literal blur, but not so when I use S-Video. It's really weird. Mine is a GPM-02.
I've observed the same with my 2 chip consoles. It's very odd indeed, the rgb traces collect a ton of noise and are very soft from the multi out, yet the s video signal is much cleaner (yet still soft). Component mod is as sharp as s video, but looks better than s video since color isn't modulated and demodulated.

There is a lot of structure to the noise in rgb, such as diagonal lines. I assume a bypass would help greatly with this.
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BrianC
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by BrianC »

I noticed the same thing with my SNES (which is an earlier model, AFAIK). I ended up hooking up the Super NT to the Sony TV with component via DAC and hooking the SNES back up to S-Video on the larger CRT. Super NT with DAC is somewhat disappointing in S-Video in comparison. Nice and sharp, but the colors are washed out, unlike component on the Super NT using the DAC, which is both sharp and colorful. Mega SG has the same issue with S-Video.
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Josh128
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by Josh128 »

Guys, had the same issue years ago and a lot of people thought I was crazy. Pictures in the thread below, and on some CRTs the issue was even more pronounced than on that 27" Trinitron.

viewtopic.php?f=6&t=53290
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TooBeaucoup
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by TooBeaucoup »

Josh128 wrote:Guys, had the same issue years ago and a lot of people thought I was crazy. Pictures in the thread below, and on some CRTs the issue was even more pronounced than on that 27" Trinitron.

viewtopic.php?f=6&t=53290
Gross! Look at the white ghosting on that text!

Image
yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

That's pretty interesting. I've never looked at the S-ENC chip's output myself. I wonder if it's just a side effect of the transcoding process or if there was some kind of compensation applied intentionally. All the outputs begin at the analog RGB output, so it can only get "worse" from there. Of course the RLPF attempts to improve quality to some degree, but ultimately it's more distorted than the original signal.
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maxtherabbit
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by maxtherabbit »

TooBeaucoup wrote:
maxtherabbit wrote:
BazookaBen wrote:
Out of curiosity, last night I dug out my 2-chip SNES, and s-video really does seem sharper than RGB out. It was just a quick test in a couple games, so nobody should take my word for it.

But I'm wondering how that would happen. Maybe luma and chroma are passed through more properly tuned components than than the RGB lines?
I've recently used my SHVC-CPU-01 through both Y/C and RGB and I cannot say that I agree
My 2-chip in S-Video is noticeably sharper than its RGB output. I'm sure this varies heavily from console to console, though. Mine in RGB is a literal blur, but not so when I use S-Video. It's really weird. Mine is a GPM-02.
the GPM-02 is basically the worst SNES console ever built, I would not read too much into this
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TooBeaucoup
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by TooBeaucoup »

maxtherabbit wrote:the GPM-02 is basically the worst SNES console ever built, I would not read too much into this
Why not? There's likely a few million consoles with this revision, so I'd say it's quite an important and fair point to bring up that s-video is far superior here.
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buttersoft
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by buttersoft »

TooBeaucoup wrote:
maxtherabbit wrote:the GPM-02 is basically the worst SNES console ever built, I would not read too much into this
Why not? There's likely a few million consoles with this revision, so I'd say it's quite an important and fair point to bring up that s-video is far superior here.
No, i think that was his point. S-Video may well be superior, but that doesn't mean it's going to be so on other revisions and everything is in need more testing for this, as the GPM-02 is known to be really bad when it comes to RGB. That's all.
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TooBeaucoup
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by TooBeaucoup »

buttersoft wrote:
TooBeaucoup wrote:
maxtherabbit wrote:the GPM-02 is basically the worst SNES console ever built, I would not read too much into this
Why not? There's likely a few million consoles with this revision, so I'd say it's quite an important and fair point to bring up that s-video is far superior here.
No, i think that was his point. S-Video may well be superior, but that doesn't mean it's going to be so on other revisions and everything is in need more testing for this, as the GPM-02 is known to be really bad when it comes to RGB. That's all.
Well, like I said, I'm sure there's a lot of this model out there, so it's not exactly an anomaly. That said, your point isn't a bad take either. I'd say it's worth mentioning with clarifying it's highly dependent on board revision. Something worth nothing somewhere like RetroRGB's site, perhaps.
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maxtherabbit
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by maxtherabbit »

TooBeaucoup wrote:
maxtherabbit wrote:the GPM-02 is basically the worst SNES console ever built, I would not read too much into this
Why not? There's likely a few million consoles with this revision, so I'd say it's quite an important and fair point to bring up that s-video is far superior here.
Sure as long as you make it clear that it's specific to that revision I have no objection. But it's easy to inadvertently launch a disinformation campaign before you realise it everyone is going around switching every single 3-chip SNES to Y/C
yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

From what I've seen, I think the RGB and APU revisions take the cake for worst video quality because they have that distinct 3.58M interference pattern (diagonal lines). Besides board layout differences, the base video quality between GPM-02 to APU revisions should be similar because they all used the same PPU2 revision (though GPM-02 had a mixture of PPU2 rev B and C). Better capture comparisons between RGB and S-Video outputs will be needed to figure out what's going on. I personally can't be bothered though.

During my break, learned more about proper board layout practices and decided to start up again. I just finished designing a board that will provide a robust power distribution network to the PPU2 chip. No RLPF shenanigans yet. I just want to isolate the analog output as much as possible and see what I can do from there.
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buttersoft
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by buttersoft »

Well, i bought some TLV35444 amps like djago suggested, though from eBay, and when i subbed them onto my working unit the results were not good. One chip had no green. And one produced a distinctly yellow output - so, it probably had weak blue. My fault for getting them from Ebay.

I'll try again with better 3544's from mouser or something when i can justify filling a cart.
yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

Been a long while since my last post. I assembled a mod board in late June with a work-in-progress circuit and it turned out mostly good. It still needs some work in the post-LPF, but I may or may not revisit it someday. I guess the easiest thing to do is post a screenshot to compare with other people's results. My console is still assembled and functional, so here's a fresh frame capture the SMB3 title screen to compare with dajigo's results:
Spoiler
Image
There's still a tiny bit of overshoot visible on the edges, and it looks worse on fade-ins and fade-outs. The overall design complexity and cost is probably more than it's worth at this point in time. Like what Opatus did with his digital TST pins project, the PPU2 chip here was desoldered from the motherboard and an adapter board was soldered in its place. The PPU2 chip was soldered to the mod board with its own regulated 5 VDC supply to keep the quality as clean as possible, and the whole assembly attached to the adapter board. Unfortunately, there is still internal self-aggression noise on the die itself, so there's a limit to how clean it can get. Even so, it does seem to be a bit cleaner than before.

I have since moved onto exploring the digital TST pin outputs, but haven't made much progress yet. While my SNES is still (sorta) in one piece, I can post more screenshots by request if anyone is interested.
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buttersoft
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by buttersoft »

yoshiyukiblade wrote:... The overall design complexity and cost is probably more than it's worth at this point in time.
Nah, the effort is really appreciated. I'd love to hear/see more, and to take a look at the schematics and info :)
yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

I'll probably put out a simplified schematic of a single channel with the changes I had planned for a future revision. Maybe also cut out all the complicated parts and use only the unbuffered RGB signals, VCC and GND for the inputs. It will most likely result in a noisier output, but the core function of the RLPF circuit will be there. This will make it easier for anyone who wants to give it a try.

My latest revision had a 3rd order Sallen-Key LPF following the RLPF circuit to smooth out all the unnecessary high frequency spikes, but it didn't turn out the way I hoped. I want to try using a simple THS7374 with LPF enabled in its place, which will require a little bit of rework to get the proper output voltage.
yoshiyukiblade
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by yoshiyukiblade »

Ok, here's an experimental RLPF circuit for anyone who's interested. Disclaimer: I'm not responsible for any accidents or damage done to the console as a result of attempting this modification. Attempt this modification at your own risk!
Spoiler
Image
Notes:
- I haven't tested the latter half of the circuit (after the OUT1 node), but the calculations should be good.
- This for RGB output only. Unlike the JP mod that sits inline with the stock circuit, this one goes straight to the RGB multi-out pins and thus won't work with S-Video, composite, or RF.
- I haven't tested this with the RGB and APU motherboard revisions, but I think the reference designators are correct. Someone else will have to confirm it.
Jon Nielsen
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Re: An actual SNES mod to sharpen the pixels of 2-CHIP conso

Post by Jon Nielsen »

I have now performed this mod on a SNSP-CPU-02 SNES with pleasant results - after some experimenting.

I plan to perform the mod on SHVC-CPU-01 and eventually my childhood SNSP-CPU-01, once I've learned more about how it actually works ;-)

Here's what was done based on ideas from this thread:

1. Used buttersoft's PCB with a TLV3544, the SNES' transistors and otherwise with components as specified.

Result: Overly bright image, strong jailbars, a deblur effect that looks like the OSSC' RLPF cranked way up, and wavy image.

2. Replaced electrolytic caps and voltage regulator, added 470uF cap to output, replaced 1uF SMD cap with 22uF one. Stacked C90-95 with 10uF caps.

Result: Completely stable picture, jailbars noticable in bright areas, deblur effect still too harsh.

3. Added 270pF caps on Q4, Q6, Q8.

Result: Noticable softness reintroduced, deblur not reversed entirely. Picture still too bright.

4. Installed borti's SNESRGB bypass as his guide suggests for a PAL SNSP-CPU-01/02.

This meant removing removing transistors (and the 270pF caps) and replacing several resistors.

Result: Brigthness corrected, colors look "vivid", picture is pleasant.

Overall I'd say with my current configuration, maybe 70-80% of the blur is gone. With optimal sampling it looks sort of like a 1CHIP without bypass or C11 fix.

I'll take and post pictures next time I do this mod. Right now I'm just enjoying putting the console through its paces using the R5X, scanlines - and softening filter ironically ;-)
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