Super SD System 3

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SavagePencil
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Re: Super SD System 3

Post by SavagePencil »

FBX: Your amp is upstream of the wonky op-amp with floating inputs, right?
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opt2not
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Re: Super SD System 3

Post by opt2not »

FBX wrote:With this, I was able to reduce the background noise to 0.0017dB. The problem is, that's still enough noise that when you play the game at a loud volume level, you can still just barely hear it in silent moments.
So wait, you got the noise reduced to 0.0017dB, and you're still unsatisfied? This is starting to borderline OCD now.
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maxtherabbit
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Re: Super SD System 3

Post by maxtherabbit »

opt2not wrote:
FBX wrote:With this, I was able to reduce the background noise to 0.0017dB. The problem is, that's still enough noise that when you play the game at a loud volume level, you can still just barely hear it in silent moments.
So wait, you got the noise reduced to 0.0017dB, and you're still unsatisfied? This is starting to borderline OCD now.
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FBX
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Re: Super SD System 3

Post by FBX »

opt2not wrote:
FBX wrote:With this, I was able to reduce the background noise to 0.0017dB. The problem is, that's still enough noise that when you play the game at a loud volume level, you can still just barely hear it in silent moments.
So wait, you got the noise reduced to 0.0017dB, and you're still unsatisfied? This is starting to borderline OCD now.
The thing is, once you hear it, you can't un-hear it. So it nags into your brain because every other use of the same op-amp doesn't have that noise.

SavagePencil wrote:FBX: Your amp is upstream of the wonky op-amp with floating inputs, right?
No, if you look closely at the layout, you'll see I completely removed the original op-amp, inverting circuitry, and Vref dividing circuitry. So my amp actually replaces it rather than being 'upstream' from it.
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opt2not
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Re: Super SD System 3

Post by opt2not »

FBX wrote:
opt2not wrote:
FBX wrote:With this, I was able to reduce the background noise to 0.0017dB. The problem is, that's still enough noise that when you play the game at a loud volume level, you can still just barely hear it in silent moments.
So wait, you got the noise reduced to 0.0017dB, and you're still unsatisfied? This is starting to borderline OCD now.
The thing is, once you hear it, you can't un-hear it. So it nags into your brain because every other use of the same op-amp doesn't have that noise.
I can totally understand that. My suggestion is to power up another old console of yours (like an SNES for instance) and turn up the volume. Then go back to your PCE...you'll probably be happy with the noise level then. ;)
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FBX
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Re: Super SD System 3

Post by FBX »

opt2not wrote: I can totally understand that. My suggestion is to power up another old console of yours (like an SNES for instance) and turn up the volume. Then go back to your PCE...you'll probably be happy with the noise level then. ;)
Well I compare it to my Genesis, which you have to turn up to ear-shattering levels to hear background hum in my amp, and even then it's not the distinctive "SD card access" buzz as can be heard in the background noise when the amp is installed in the SSDS3 V2. Since we know this noise is also creeping in as visual artifacts in the video end of the card, there's clearly something wrong, and it's gotta be something looping into the analog ground plane when it shouldn't be.

Eventually I'm just going to map the entire layout of the SSDS3 and volumetrically test every component and chip for what is getting tied to analog ground that might be inducing such distinctive noise of the SD card being accessed.
SavagePencil
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Re: Super SD System 3

Post by SavagePencil »

FBX wrote:
SavagePencil wrote:FBX: Your amp is upstream of the wonky op-amp with floating inputs, right?
No, if you look closely at the layout, you'll see I completely removed the original op-amp, inverting circuitry, and Vref dividing circuitry. So my amp actually replaces it rather than being 'upstream' from it.
Apologies, that’s what I meant. It is in no way impacted by the existing amp, which you’ve confirmed.
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FBX
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Re: Super SD System 3

Post by FBX »

So after listening to the SD card access noise (amplified many times), I got to thinking this: What if somehow digital ground is 'leaking' noise into analog ground? How exactly does the NEC console handle digital ground as opposed to analog ground? I'm guessing both eventually have to go to the same common ground in the console, but what circuitry is used to keep them from cross-talking?
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Syntax
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Re: Super SD System 3

Post by Syntax »

Nothing. It's a star ground system. They both meet at a central point atleast on the white pce.
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Re: Super SD System 3

Post by broken »

Voultar recently (like this week) on a rev 2 clipped the digital ground pins and moved everything over to the analog ground.


Made zero difference.


I sent Voultar another rev 2 board this week for further experimenting.

He is still thinking it's power related.
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FBX
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Re: Super SD System 3

Post by FBX »

broken wrote:
He is still thinking it's power related.
And yet when I supplied external 5V to my bypass amp board, I could still hear the exact same background noise coming from the SSDS3 when I amplify the output during silent parts. So if it's power related, it would have to be something causing interference on the entire analog ground plane.
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Syntax
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Re: Super SD System 3

Post by Syntax »

I've completely powered analog and digital planes with seperate power supplies and tied all ground to a central point.

That's 3 2amp regulators powering the system with adequate filtering on each. Didn't help.
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FBX
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Re: Super SD System 3

Post by FBX »

Just to see what would happen, I measured resistance between the analog ground plane and the digital plane on the SSDS3 completely disconnected from the console. I was expecting to see no connection, but instead measured 11.4 Megaohms. Not sure if that means anything relevant, but I would have thought with the device disconnected from the console, I wouldn't get a reading from those two sources. So I'm guessing some of the IC's on the board handle both analog and digital grounds, causing some small degree of connection.

At any rate, it's very perplexing.

Edit: One to knock off the bucket list: I tried disconnecting the analog audio ground plane pin and running the SSDS3 without ground for audio. Unfortunately video still had interference. So it may be something power related after all.
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Syntax
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Re: Super SD System 3

Post by Syntax »

cr4zymanz0r wrote:
FBX wrote: Yeah I know that was a major problem in V1, but I honestly can't figure it out. I was sure it was Vcc, but everything seems to be leading back to ground issues.
At this point I don't even see what could theorized to be the issue other than a ground issue or component improperly implemented that's adding noise to ground.

Whats got me confused is people have clean picture from a bypass board with the SSDS3 rgb amp still running in the background.

Voultars board and the SSDS3 RGB circuit with the correct cable are pretty much identical besides the way sync is processed. So WTF??
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FBX
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Re: Super SD System 3

Post by FBX »

Syntax wrote:

Whats got me confused is people have clean picture from a bypass board with the SSDS3 rgb amp still running in the background.

Voultars board and the SSDS3 RGB circuit with the correct cable are pretty much identical besides the way sync is processed. So WTF??
Yeah I looked at the circuit on the SSDS3 for video and don't see anything wrong visually. However, it is a 4-layer board design, and it's quite possible there's some coupling noise going on. This might explain why I get superb RGB using Voultar's bypass board in the console, even though I'm using the SSDS3 to run the games.

In other news, I'm getting some excellent feedback for discovering the audio fix in replies to the TO thread:

Image
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Syntax
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Re: Super SD System 3

Post by Syntax »

I just tried routing the 3.6meg pullups on RGB and the ths amp to a separate power source, csync directly from the pce buffered by my extron. Still have diagonal noise.



I know its something to do with audio.
If you play Bonks Revenge, get to level 2 where you can really see the diagonal lines in the green bushes and blue sky then pause the game youll notice the diagonal lines change rate and density.

I've fixed a similar problem with the N64 where the audio and controller input make the 3.3v power source dirty. Fixed it with an LDO but the same hasn't worked here for the PCE.
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opt2not
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Re: Super SD System 3

Post by opt2not »

FBX wrote: In other news, I'm getting some excellent feedback for discovering the audio fix in replies to the TO thread:

Image
LOL yeah I saw that and had a chuckle. Whoops!
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FBX
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Re: Super SD System 3

Post by FBX »

Syntax wrote:I just tried routing the 3.6meg pullups on RGB and the ths amp to a separate power source, csync directly from the pce buffered by my extron. Still have diagonal noise.

I know its something to do with audio.
If you play Bonks Revenge, get to level 2 where you can really see the diagonal lines in the green bushes and blue sky then pause the game youll notice the diagonal lines change rate and density.
I keep jumping back and forth between something in the grounding causing a loop, something in the power supply, and something in the audio. It's very hard to pin down. I may get desperate and start pulling ALL of the audio components off the board, including the DAC. If there's still video noise, then it at least narrows the search.
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FBX
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Re: Super SD System 3

Post by FBX »

Latest test: Pulling the DAC chip completely off the board did not resolve the video or audio noise. So it's not the dac, nor is it the op-amp.
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Syntax
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Re: Super SD System 3

Post by Syntax »

Long shot but what happens if you take ground for Voutars board from the SSDS3 din sheild?

If it introduces diagonal noise on screen then..
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FBX
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Re: Super SD System 3

Post by FBX »

Syntax wrote:Long shot but what happens if you take ground for Voutars board from the SSDS3 din sheild?

If it introduces diagonal noise on screen then..
Interesting idea! I'll try ground, then power, then both.
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Syntax
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Re: Super SD System 3

Post by Syntax »

Awesome! Awaiting results.

Just noticed something else odd.

I can see the diagonal noise on the opening ssds3 menu clearly but if I change to the bios menu the noise changes direction and runs vertically up the screen.
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Syntax
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Re: Super SD System 3

Post by Syntax »

Heres a short video of the on screen noise changing direction when I switch from the main menu to the bios menu.

I switch from main to bios twice in this short 10 second video.

http://s000.tinyupload.com/index.php?fi ... 5862156811
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FBX
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Re: Super SD System 3

Post by FBX »

Well I didn't need to try power. Pulling ground from the SSDS3 Din made the interference blatantly obvious from my RGB bypass mod out the side of the Super Grafx. When I disconnected that ground line and switched back to local ground next to the bypass board, the interference was almost completely eliminated. There was only a very faint appearance of thin diagonal black jail bars about 10 pixels apart.

So what does this mean then? My best guess is EMI generated by the SSDS3 somehow corrupting console ground?

Edit: When I put my Super Grafx back together, the remaining faintest hint of diagonal lines disappeared completely on my RGB bypass output, so it seems that heavy-duty ground plate on the bottom of the system helps protect from EMI I'm guessing. /shrug
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keropi
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Re: Super SD System 3

Post by keropi »

just a head-up, FW 1.02 has been released: https://forums.terraonion.com/viewtopic.php?f=12&t=142
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Voultar
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Re: Super SD System 3

Post by Voultar »

There are definitely some zoning problems with the board that certainly contributes to the noise.

https://twitter.com/Voultar/status/981732021826449408

^ This is mostly applicable to V2 revisions, as well. In an effort to alleviate some of the inductance AND capacitance coupling, work all of the video circuitry OFF of the SSDS3 any bypass.

I felt like I had a pretty good handle on this a couple of months ago. But I didn't want to be burdened with supporting something that I can't personally thoroughly test on every type, variation and permutation of PC-E hardware. Nonetheless, the FU-RGB board is free. Test it.
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FBX
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Re: Super SD System 3

Post by FBX »

Voultar wrote:There are definitely some zoning problems with the board that certainly contributes to the noise.

https://twitter.com/Voultar/status/981732021826449408

^ This is mostly applicable to V2 revisions, as well. In an effort to alleviate some of the inductance AND capacitance coupling, work all of the video circuitry OFF of the SSDS3 any bypass.

I felt like I had a pretty good handle on this a couple of months ago. But I didn't want to be burdened with supporting something that I can't personally thoroughly test on every type, variation and permutation of PC-E hardware. Nonetheless, the FU-RGB board is free. Test it.

Yep, after discovering analog ground was corrupted, I started l looking at the trace for for it on the video side in the V2 and discovered they have the trace for it embedded in one of the middle layers of the board, so it's literally sandwiched into areas with high-speed data lines. The sound side is no better off either. Even with my cap fix, you can still just barely make out the ARM access of the SD card when you turn the volume up loud. In reality, you shouldn't be able to hear it at all unless ground is corrupted. So the only way to 100% fix these issues is to strip ALL components for both video and audio, isolate them on separate mod boards, and completely disconnect the analog ground pins on the SSDS3. Just what seems to be the case in my opinion.
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cr4zymanz0r
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Re: Super SD System 3

Post by cr4zymanz0r »

FBX wrote:So the only way to 100% fix these issues is to strip ALL components for both video and audio, isolate them on separate mod boards, and completely disconnect the analog ground pins on the SSDS3. Just what seems to be the case in my opinion.
So, that means you'll be making a PCB to completely replace the sound circuit? ;)

I'd be up for doing all this to make mine perfect once there's sound PCB and things are verified (I'm hesitant to remove tiny surface mount parts myself before the end result is fully known).
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FBX
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Re: Super SD System 3

Post by FBX »

cr4zymanz0r wrote:
FBX wrote:So the only way to 100% fix these issues is to strip ALL components for both video and audio, isolate them on separate mod boards, and completely disconnect the analog ground pins on the SSDS3. Just what seems to be the case in my opinion.
So, that means you'll be making a PCB to completely replace the sound circuit? ;)

I'd be up for doing all this to make mine perfect once there's sound PCB and things are verified (I'm hesitant to remove tiny surface mount parts myself before the end result is fully known).
It's something I will definitely be working on, but I'm in a holding pattern for the next couple weeks as I'm pulling in donations to pair with my own money to get a Rigol scope. Can't really spend money on new proto boards until I get that out of the way.
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keropi
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Re: Super SD System 3

Post by keropi »

I just saw the post on FBX's patreon page, the rgb lines on the sss3 have issues and even spill interference back to the console... wow
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