GBS 8200 with RGB modded Snes mini, need advice.

[ProfessorProfessorson]

Modded my Snes Mini for sync and RGB output. I did individual jacks for each signal, because I planned to make a custom cable when the GBS arrives. Anyway, not finding much info out on the net about this, so I have been posting around trying to find out if this will work fine as is with the GBS, or if I need to do anything extra. This is the mod I did for the RGB and Sync output:



I have read that the GBS has issues sometimes with sync signals from different game systems, so was wondering if anyone knew if this would work fine, or if I will have to do anything extra to the sync output of the Snes Mini in order to get it working. Anyone know?

[NightWolve]

Something tells me tapping the Sync pin for direct use is probably not a good idea, but I haven't looked at this closely.

I assume you already know, these mini/junior units can have their S-Video support restored easily enough off that S-RGB encoder chip:
http://console5.com/wiki/SNES#S-Video_Output_for_SNES_2_.2F_Junior_.28SNN-CPU.29

But anyhow, if you do have trouble with a clean Sync for this GBS device you mention, besides using the Composite source, you could instead tap the Luma/Y signal for it (it's cleaner than Composite, no Chroma, just Luma and Sync). It's properly amplified coming off that chip seems, just needs a 220 uF cap and 75 Ohm resistor just like how console5 recommends to use it for S-Video restoration and how you already did for the RGB pins.

[ProfessorProfessorson]

Something tells me tapping the Sync pin for direct use is probably not a good idea, but I haven't looked at this closely.

I assume you already know, these mini/junior units can have their S-Video support restored easily enough off that S-RGB encoder chip:
http://console5.com/wiki/SNES#S-Video_Output_for_SNES_2_.2F_Junior_.28SNN-CPU.29

But anyhow, if you do have trouble with a clean Sync for this GBS device you mention, besides using the Composite source, you could instead tap the Luma/Y signal for it (it's cleaner than Composite, no Chroma, just Luma and Sync). It's properly amplified coming off that chip seems, just needs a 220 uF cap and 75 Ohm resistor just like how console5 recommends to use it for S-Video restoration and how you already did for the RGB pins.

Ahh yeah I already have svideo restored on it. I am mainly wanting to get RGB going with that GBS 8200 so I have multiple video options. Basically wondering if the GBS will be fine with sync off the chip, or if I need to pull it from elsewhere and use a sync stripper.

[NightWolve]

Well, best and safe bet when you get it is to first try using the Composite signal and see if it just accepts that - I would still do that even knowing I have access to a clean H/V Sync pin if it works. Next, I'd actually try the Luma/Y signal that you already tapped for S-Video like I mentioned. It's a little cleaner minus the Chroma, so worth a shot. If that all fails, then yeah, you're gonna have to play with that clean Sync pin, either properly amp'ing it or just prepping it if it's strong enough.

For Sync amp'ing, there's now Steve's somewhat universal circuit used in his latest YPbPr/Component circuit design: https://www.pcenginefx.com/forums/index.php?topic=13231.0

Actually, I cropped it up for ya:


Just in case all else fails and instead of buying that Sync Stripper chip, you could try his circuit instead which you can build from spare parts.

That's about it, unless somebody else has specific knowledge with the video converter and these SNES units. Good luck!

EDIT: http://gamesx.com/wiki/doku.php?id=av:snes2rgb

Well, from what I'm reading, the SNES Mini/Jr. doesn't need amp'ing for that Sync pin (7) either... I guess you'll find out soon enough. Would be nice if an EE like Steve had done it to tell you what kind of prepping to use, maybe just a 22 uF cap from the pin to the monitor/device or something (I feel safer if there's some component between the chip and the TV/monitor/device, like an output cap, or even a diode, etc.). But yeah, you likely won't have to amp it.

[technozombie]

Do you like the GBS-8200? I have a Shinobi PCB that I'd like to build a cabinet for and use a PC monitor.

[NightWolve]

Do you like the GBS-8200? I have a Shinobi PCB that I'd like to build a cabinet for and use a PC monitor.

because I planned to make a custom cable when the GBS arrives.

Hasn't arrived yet, is why he's asking in advance about how picky it is with the H/V Sync signal.

[technozombie]

Haha I read the post and later looked up what a gbs 8200 was. I should have re-read doh!

[ProfessorProfessorson]

Yeah that sync pin not having anything added in any of the post I came across had me a little concerned. What I opted to do was add nothing, yet. When the GBS arrives I was going to put a 220uf cap or whatever on the cable I was going to run from the sync signals output jack, as a test to make sure it did not inhibit anything.

If it checked out ok then I was going to pop the system back open and solder one in place. If it ends up causing issues, I was going to lower the value a bit and try again, etc. As is I am thinking it doesn't need to be amped, and I am more concerned that what is coming out may be too strong voltage wise.

Basically wanted to wait to make sure what worked best on that line before I soldered anything on to it inside the system. I know a lot of the RGB cables made for the Snes originally had caps in them on the RGB lines, but was not sure if they had one in place for the sync line too. And even then, the S-RGB chip is different then the S-ENC chip, so that in itself is an issue. Not much is really posted/documented concerning this matter for the S-RGB on the Snes mini, and what it may need may be different then the S-ENC.

As for the other, Herc/Tim is sending me what I need to toss together a sync stripper also to help save me time and money. US sellers want to charge way too much for the LM1881, and the cheaper alternative is opting for Asia based sellers and super long ship times. We were discussing this issue tonight, that there may be the possibility that I will need to use one, so he is making sure I will be prepared in case that happens.

[bust3dstr8]

I have a couple LM1881 pcbs left if you want a populated board. I just don't have any resistors for the output, I've never needed it though.

[ProfessorProfessorson]

Yeah I just saw your thread about that. Drop me a PM if you still have a spare left that you wanna send.

[ProfessorProfessorson]

Just to update this, GBS arrived and it worked with the Snes Mini fine. I added a 220uf cap to the sync line and that did not cause any issues, so basically everything is good to go. One issue, not really the Snes or GBS to blame, is that it cant lock on to the first Ranma 1/2 game. I knew though that this game may cause an issue. It seems to run in a strange resolution or does something to the Snes signal when its played. I cant really describe it, but you'd know it if you saw it running, that it doesn't look normal.

I have tried it on two different Snes decks on LCD and CRT and it looks funny on either one. Via s-video the Toshiba lcd tv in my room coped with it better then the CRT tv in my sons room does, but yeah in general I suspected due to how the game acts that the GBS would not be able to display it, and I was right. The other 30 or so games I have all worked fine, including the 2nd Ranma 1/2 game, Bakuretsu Rantohen.

[thesteve]

i have the GBS-8200
it works perfect with my puckman PCB, has a slight sync issue with PCE or MVS
dont think ive run anything else through it
nothing can be done if it doesnt like your screen res

[ProfessorProfessorson]

i have the GBS-8200
it works perfect with my puckman PCB, has a slight sync issue with PCE or MVS
dont think ive run anything else through it
nothing can be done if it doesnt like your screen res

Yeah I'm shedding no tears over the first Ranma not being playable. It's really not that good. The 2nd one is worlds better. Surprised you had issues with the Neo MVS, seems like everyone uses this thing with the Neo.

[thesteve]

It was playable. Just the top few lines of pic were out of sync
I thought that was just how it ran till I got puckman running and it was flawless