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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Thu Oct 04, 2018 9:53 pm 


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energizerfellow‌ wrote:
mikechi2 wrote:
Thanks for explaining... I actually had a similar discussion with Rob. The regular PS1 cables with the coupling caps *should* work fine on a PS2. But I think what you'd guys really need is a sync stripper for the PS2 @ 480p and above?

With properly shielded sync-on-luma cables and modern displays/scalers I think most of the issues are solved outside of the PS1's coupling capacitors, no sync strippers needed.

sync on luma doesn't work at 480p and up, the PS2 turns off the luma pin


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Thu Oct 04, 2018 10:18 pm 



Joined: 01 Jul 2017
Posts: 26
maxtherabbit wrote:
energizerfellow‌ wrote:
mikechi2 wrote:
Thanks for explaining... I actually had a similar discussion with Rob. The regular PS1 cables with the coupling caps *should* work fine on a PS2. But I think what you'd guys really need is a sync stripper for the PS2 @ 480p and above?

With properly shielded sync-on-luma cables and modern displays/scalers I think most of the issues are solved outside of the PS1's coupling capacitors, no sync strippers needed.

sync on luma doesn't work at 480p and up, the PS2 turns off the luma pin



Gotcha, so it sounds like from all the discussions what is really needed is a circuit that strips the sync from green as necessary as well as select the correct sync source (stripped green, or CVBS) as appropriate.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Thu Oct 04, 2018 10:27 pm 



Joined: 27 Sep 2018
Posts: 93
maxtherabbit wrote:
sync on luma doesn't work at 480p and up, the PS2 turns off the luma pin

Pretty sure the chroma, luma, and CVBS are all cut at once for anything >15khz or in YPbPr mode on the PS2/PS3? But how big is the sync control need, really, when both the gscartsw and OSSC now support SoG/YPbPr and the PVM guys can just hit the sync source button?


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Thu Oct 04, 2018 11:41 pm 



Joined: 03 Jun 2018
Posts: 37
Retro Access was able to solve the PS1/PS2 cable differences by just using higher farad capacitors in the cable. Since I have both consoles, decided to just get one of each since I wanted the lightgun version from Retro Gaming Cables and not deal with the pigtail on Retro Access version of the cable (that I can see myself accidentally tearing off with how I have my console tower currently configured).

Also when Sync on Luma is available, it is always better to go with that over Sync on Composite. There will be less noise issues since less traffic is being sent through the same cable. I can see Mike using SoC here due to the wiring differences between NTSC and PAL (and how the PAL version doesn't have S-Video out).


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 05, 2018 12:10 am 


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Dazdigo wrote:
Also when Sync on Luma is available, it is always better to go with that over Sync on Composite. There will be less noise issues since less traffic is being sent through the same cable. I can see Mike using SoC here due to the wiring differences between NTSC and PAL (and how the PAL version doesn't have S-Video out).

since he's stripping the sync on a board located at the multiout, there's no argument against CVBS-as-sync - there's no cable for it to travel through to cause coupling related issues


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 05, 2018 12:10 am 


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energizerfellow‌ wrote:
maxtherabbit wrote:
sync on luma doesn't work at 480p and up, the PS2 turns off the luma pin

Pretty sure the chroma, luma, and CVBS are all cut at once for anything >15khz or in YPbPr mode on the PS2/PS3? But how big is the sync control need, really, when both the gscartsw and OSSC now support SoG/YPbPr and the PVM guys can just hit the sync source button?

true, and a good point


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 05, 2018 4:13 am 



Joined: 19 Jul 2017
Posts: 854
energizerfellow‌ wrote:
maxtherabbit wrote:
sync on luma doesn't work at 480p and up, the PS2 turns off the luma pin

Pretty sure the chroma, luma, and CVBS are all cut at once for anything >15khz or in YPbPr mode on the PS2/PS3? But how big is the sync control need, really, when both the gscartsw and OSSC now support SoG/YPbPr and the PVM guys can just hit the sync source button?

Luma, chroma, and CVBS are cut for >15kHz when in RGB mode. I imagine chroma and CVBS get cut in YPbPr as well, but not luma, because luma is Y and integral to YPbPr. :)

The main reasons for automatic RGsB->RGBS conversion are so that you don't have to toggle input mode on the OSSC, and to enable the PS2 to continue to operate with SCART equipment when switching to 480p and better video modes.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 05, 2018 2:54 pm 



Joined: 03 Jun 2018
Posts: 37
Which is why the new gscartsw is so appealing. I can't wait to get mine.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Mon Oct 08, 2018 3:18 pm 



Joined: 05 Dec 2012
Posts: 420
mikechi2 wrote:
The regular PS1 cables with the coupling caps *should* work fine on a PS2. But I think what you'd guys really need is a sync stripper for the PS2 @ 480p and above?

Ste did some research on this and found that as long as a much higher rating cap was used, it would be fine in both consoles. I think it was 1000uF instead of 220uF, but I can't remember.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Mon Oct 08, 2018 4:05 pm 



Joined: 19 Jul 2017
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retrorgb wrote:
mikechi2 wrote:
The regular PS1 cables with the coupling caps *should* work fine on a PS2. But I think what you'd guys really need is a sync stripper for the PS2 @ 480p and above?

Ste did some research on this and found that as long as a much higher rating cap was used, it would be fine in both consoles. I think it was 1000uF instead of 220uF, but I can't remember.

The Retro-Access PS1/2/3 cables were indeed advertised to use 1000uF/1mF caps.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Mon Oct 08, 2018 6:29 pm 



Joined: 01 Jul 2017
Posts: 26
nmalinoski wrote:
retrorgb wrote:
mikechi2 wrote:
The regular PS1 cables with the coupling caps *should* work fine on a PS2. But I think what you'd guys really need is a sync stripper for the PS2 @ 480p and above?

Ste did some research on this and found that as long as a much higher rating cap was used, it would be fine in both consoles. I think it was 1000uF instead of 220uF, but I can't remember.

The Retro-Access PS1/2/3 cables were indeed advertised to use 1000uF/1mF caps.


It hurts me to hear that 1mF caps are being used. :cry:


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Mon Oct 08, 2018 11:45 pm 


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mikechi2 wrote:
nmalinoski wrote:
The Retro-Access PS1/2/3 cables were indeed advertised to use 1000uF/1mF caps.


It hurts me to hear that 1mF caps are being used. :cry:

Why?


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Tue Oct 09, 2018 12:30 am 



Joined: 01 Jul 2017
Posts: 26
maxtherabbit wrote:
mikechi2 wrote:
nmalinoski wrote:
The Retro-Access PS1/2/3 cables were indeed advertised to use 1000uF/1mF caps.


It hurts me to hear that 1mF caps are being used. :cry:

Why?


They're big, ugly and prone to leakage (electrically and physically). To me, they should never be used as part of a signal path, and only as a last resort for power supply decoupling. Ceramic MLCCs are usually sufficient for low voltage applications and there are ways to compensate for a smaller coupling capacitor using slightly more complex circuitry.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Wed Oct 10, 2018 12:07 am 



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Posts: 575
The 1000uF fix is a workaround that's acceptable at best, as the effective total capacity when used with a PS2 will be less than 220uF.
The problem of course is that you want a multi cable, but one source has coupling caps and the other doesn't.
I don't think there's a better way than the 1000uF workaround.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Wed Oct 10, 2018 12:10 am 



Joined: 01 Jul 2017
Posts: 26
rama wrote:
The 1000uF fix is a workaround that's acceptable at best, as the effective total capacity when used with a PS2 will be less than 220uF.
The problem of course is that you want a multi cable, but one source has coupling caps and the other doesn't.
I don't think there's a better way than the 1000uF workaround.


SAG correction or AC-coupling to a high input impedance stage, clamping to ground and then driving with a DC amp is the cleanest way to do it and gets rid of the caps.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Wed Oct 10, 2018 12:16 am 



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Quote:
SAG correction or AC-coupling to a high input impedance stage, clamping to ground and then driving with a DC amp is the cleanest way to do it and gets rid of the caps.


Interesting, if it doesn't add too much noise.
I don't know how much the inherent noise of active devices affects these rather low bandwidth signals.
Can you do it noise free? :)

Edit:
And the signals will be DC coupled then? Is this safe?


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 12, 2018 5:10 pm 



Joined: 27 Sep 2018
Posts: 93
I'm guessing this amplifier circuit could be considered universal for everything modern enough to have RGBs, but too old for YPbPr, excluding the Dreamcast/Gamecube, considering most everything uses some combination of cap+resistor? If so, the HD Retrovision guys might be onto something with a transcoder box that's basically a bump in the wire with replaceable console-specific ends.

Speaking of ends, wouldn't a shielded RJ45/RJ50 connector for the console-specific input cable be both mechanically and electrically better than the mini-DIN? Would probably need to use a connector meant for the larger diameter of CAT 6/7/8.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Fri Oct 12, 2018 9:45 pm 



Joined: 01 Jul 2017
Posts: 26
energizerfellow‌ wrote:
I'm guessing this amplifier circuit could be considered universal for everything modern enough to have RGBs, but too old for YPbPr, excluding the Dreamcast/Gamecube, considering most everything uses some combination of cap+resistor? If so, the HD Retrovision guys might be onto something with a transcoder box that's basically a bump in the wire with replaceable console-specific ends.

Speaking of ends, wouldn't a shielded RJ45/RJ50 connector for the console-specific input cable be both mechanically and electrically better than the mini-DIN? Would probably need to use a connector meant for the larger diameter of CAT 6/7/8.


Yes indeed - although for generic usage, you could drop the current biasing circuit. That's only needed for the PAL SNES.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Thu Nov 15, 2018 2:55 pm 


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Hello, I've managed to get in the list of beta testers for RetroGamingCables Universal SNES cable, but I have a few questions. I plan on testing it with my RGB modded AV Famicom and TW RGB modded N64. Now the N64 should need a cable with 220uf caps, just like an NTSC SNES cable, so I expect everything to be fine there. However, the AV Famicom has caps in already. I plan on doing tests and some captures with the caps, and then removing them and doing more tests and captures so I can compare. But just so I know what I should look for, anyone have any idea how the circuitry in this cable will work with an RGB signal that is already attenuated properly? Should I look for the same greyish black levels you get with using two 220uf capacitors in series? Or will that not happen with this cable?

Thanks in advance :D


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Sat Dec 01, 2018 9:08 pm 


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Well no one answered my question :P So I tested the universal SNES cable on my AV Famicom with two other cables; a cheap ebay cable and a RGC NTSC SNES csync Cable as a control test. I tested before and after removing capacitors from the NESRGB board. I was quite surprised to see that it's very dark with capacitors. Thankfully, it's fine once the capacitors have been removed. It seems this cable might not be a good option for NESRGB, unless they KNOW that the RGB capacitors have been removed.

Spoiler: show
Image


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Sun Dec 02, 2018 5:48 pm 


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So after another day of testing I have some results to post. Firstly, with the N64 it unfortunately has a dark image similar to the NES, but not as bad. I was expecting it to work, seeing as the N64RGB board needs a cable with capacitors just like an NTSC SNES. A little disappointing.

Then I tested it with my PAL Gamecube. I expected this to work as well, or at least display some kind of image. But the OSSC read 'No Signal'. I plugged it into my CRT and it showed a band of screen stuff rapidly rolling down the screen. Hey, Mike Chi, did you ever get to test a PAL Gamecube with this? Did you or anyone get something similar? On the plus side it wasn't too dark this time :lol: This could be due to an issue with the Gamecubes sync. I plan on asking Rob from RGC when he gets back to me, his GC cables have a 75ohm resistor between sync and ground to stop some kind of sync issue, if he thinks it's worth it I'll break open the cable and put a resistor between sync and ground before the sync stripper. I looked online but couldn't find anything, is it an LM1881 used in this?

Here's a comparison of the N64 cables and the Gamecube logo intro rolling around my screen;

Spoiler: show
Image

Image


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Sun Dec 02, 2018 11:05 pm 



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Again the PAL Gamecube!
I hear about sync issues with this console a lot. Is there anything weird going on?
I mean, except the Nintendo typical need to put a 75 Ohm to ground resistor in the console end plug? :p


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Sun Dec 02, 2018 11:19 pm 


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rama wrote:
Again the PAL Gamecube!
I hear about sync issues with this console a lot. Is there anything weird going on?
I mean, except the Nintendo typical need to put a 75 Ohm to ground resistor in the console end plug? :p


I have no idea what's happened with this cable and the Gamecube. My guess is, as this cables thing is how it handles the RGB lines, it's handling of the sync line shouldn't be effected by the special circuitry. If the image was too dark or had bad black levels, then that'd be a sign it's the RGB line attenuation. But given that the issue is that the OSSC reads 'No Sync', then it must be to do with the sync line. This doesn't happen with the other cable I use, which is a generic ebay cable with sync on composite, 220uf caps on RGB lines, and no special resistor for sync.


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 Post subject: Re: Universal SNES Output Amplifier
PostPosted: Wed Dec 05, 2018 8:00 pm 


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RGC sent an email out to all beta testers mentioning that this beta test cable is not compatible with Gamecube. So that explains the issue I had with Gamecube, however the other consoles results still stand.


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