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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Aug 11, 2016 5:11 pm 


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In our tests the RGB bypass amp significantly improved the picture, there was less noise in near-black as well as no jailbars.

Quote:
there's a new RGB bypass board with a ton of upgraded features on it


I was going to e-mail you about this and forgot, any details on who's board it is? My main objection to ArcadeTVs board is that he puts the caps on the board itself, meaning you have to modify your SCART cable. I'd much rather the mod just worked with the existing cables.
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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Aug 11, 2016 6:29 pm 



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Posts: 411
BuckoA51 wrote:
any details on who's board it is? My main objection to ArcadeTVs board is that he puts the caps on the board itself, meaning you have to modify your SCART cable. I'd much rather the mod just worked with the existing cables.

Well, you can just remove the caps and resistors from ArcadeTV's board. The caps came in handy when using cables that don't include them...but leaving the resistors made things too dark (and sent the wrong signal, etc), so I'd always remove those. db Electronics is making one of the new bypass boards (I wasn't going to say anything until there was an "announcement", but he's posted pics on twitter, so I guess the cat's out of the bag). The other board was you one you'd shown me awhile back - That has more features like IGR, but it seems to be using the older THS7314 chip and looks pretty big: https://vmod.wordpress.com/megamod-v3-0/

eric90000 wrote:
So it would basically be counter-intuitive to use an RGB board with audio amp given that I have a VA0 console with good audio

Correct - I doubt you'd hear much of a difference, if any at all.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Aug 11, 2016 6:48 pm 


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retrorgb wrote:
The other board was you one you'd shown me awhile back - That has more features like IGR, but it seems to be using the older THS7314 chip and looks pretty big: https://vmod.wordpress.com/megamod-v3-0/


That board looks like its got everything covered, even the in game reset/multi region mod I mentioned I was gonna do. You mentioned it uses the older THS7314 chip, do you think that'd make the picture from this one inferior to Arcade TV's board?

I'm currently trying to dig up some info on db Electronics version....then I guess I need to pick one of the three boards and test it out!


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Aug 11, 2016 6:51 pm 



Joined: 05 Dec 2012
Posts: 411
eric90000 wrote:
That board looks like its got everything covered, even the in game reset/multi region mod I mentioned I was gonna do. You mentioned it uses the older THS7314 chip, do you think that'd make the picture from this one inferior to Arcade TV's board?

Not inferior, equal to. Still a great picture.

eric90000 wrote:
I'm currently trying to dig up some info on db Electronics version....then I guess I need to pick one of the three boards and test it out!

Don't bother, there's no info out there yet. We'll both announce it as soon as it's available.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Sep 15, 2016 9:58 pm 


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Still currently seems that there's no availability or ETA info on any RGB bypass boards. Don't suppose anyone has leads on where to get one right now? Arcade TV, db Electronics, and the MegaMod 3.0 aren't available.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Sep 15, 2016 10:44 pm 


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retrorgb wrote:
Unfortunately, in my opinion, the bottom line is that unlike SNES (just find a 1CHIP), in order to get clean video output from a Genesis, some kind of modification is required.

Excuse me but, can I get reasons as to why the Genesis' RGB signal supposedly need mods and RGB amp bypass and all that?

It's regarded as excellent AFAIK and if a cable with boosted sync doesn't fix the jailbars problem (which it did on my model 1 VA2), then you just have to lift a pin(did this on my model 2).

In my mind the SNES is the problematic one, requiring you to hunt down a very specific console revision, whereas all Gennys output clean and crisp RGB.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 2:27 pm 



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Posts: 411
Look, if your solution worked for you, I'm happy for you. Most people would be content with an unmodified Genesis and it's RGB output is certainly much better then composite. The purpose of my site and discussions like this is to find ways to tweak consoles to get the absolute best out of them. I imagine most people wouldn't bother...but a lot of us here will do whatever is necessary to get the best picture possible. To directly address your post (with no attitude intended, just being blunt):

Most Genesis revisions output very noisy video and are far from "clean and crisp". To make things more complicated, there are MANY revisions of the Genesis motherboard and each have their own issues. There's no "just lift a pin" fix that applies to all.

That being said, two boards are being released soon that will be "universal" fixes to all Genesis issues; One uses the on-board encoder, the other uses a new one. I'll be testing both, but my guess is they'll be equal in quality and people would choose based on options and what fits their needs best.

Also, SNES is simple: Get a mini, connect RGB (the right way), done.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 2:30 pm 


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Voultar is working on one, isn't he? He's been teasing Genesis and SNES RGB bypass boards on Twitter.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 3:09 pm 


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Guspaz wrote:
Voultar is working on one, isn't he? He's been teasing Genesis and SNES RGB bypass boards on Twitter.


Oh cool, just followed him on Twitter. So that's 4 different boards on the go, still no current availability haha :(


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 10:02 pm 


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So, this was just announced by dbElectronics on Twitter: http://db-electronics.ca/2016/09/16/rgb ... ng-design/.

Literally exactly what I needed. Has a built in Genesis 2 style connector and a Mega Amp for crappy audio models. Can't wait for this.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 10:31 pm 


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I'm getting the feeling that Voultar's and dbElec's two boards are literally the ones that RetroRGB is talking about.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Sep 16, 2016 11:02 pm 


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Guspaz wrote:
I'm getting the feeling that Voultar's and dbElec's two boards are literally the ones that RetroRGB is talking about.


Oh shit I totally missed Bob's response earlier, yeah they're most likely the ones he's talking about! Voultars one doesn't seem to have an RGB encoder on it, but it has a transistor (which is presumably to accomodate s-video?).

dbElectronics' new board will be my choice I think, as it also has the mega amp and a built in connector for stereo audio. I've got 3 Mega Drives all sitting on my desk waiting to be freed from jail :P.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 2:36 am 


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Are issues with RGB jailbars on Genesis still a thing? I haven't tried it on a Genesis model 1, but I was able to eliminate the jailbars on RGB on a model 2 that had a Sony video encoder (CXA1145 I think).

My recollection is on the AV connector the pin for csync (most cables use composite video for sync) is connected to the sync input pin of the video encoder. This did not give me a usable sync signal on any of my equipment, so I cut the trace. Then connected the sync output pin of the video encoder to a 220uF capacitor, then a 75 ohm resistor, then connected that to the csync output pin on the AV port. That gave me proper csync and it had no jailbars. The RGB signals themselves were never modded/bypassed/etc.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 3:00 am 


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Bob does either one have an IGR? It's a no brainer for people who use flash carts.

retrorgb wrote:
Look, if your solution worked for you, I'm happy for you. Most people would be content with an unmodified Genesis and it's RGB output is certainly much better then composite. The purpose of my site and discussions like this is to find ways to tweak consoles to get the absolute best out of them. I imagine most people wouldn't bother...but a lot of us here will do whatever is necessary to get the best picture possible. To directly address your post (with no attitude intended, just being blunt):

Most Genesis revisions output very noisy video and are far from "clean and crisp". To make things more complicated, there are MANY revisions of the Genesis motherboard and each have their own issues. There's no "just lift a pin" fix that applies to all.

That being said, two boards are being released soon that will be "universal" fixes to all Genesis issues; One uses the on-board encoder, the other uses a new one. I'll be testing both, but my guess is they'll be equal in quality and people would choose based on options and what fits their needs best.

Also, SNES is simple: Get a mini, connect RGB (the right way), done.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 3:12 am 


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tjstogy wrote:
Bob does either one have an IGR? It's a no brainer for people who use flash carts


The MegaMod board has IGR, but it won't be in stock for a while it seems. You could also just separately install the MD++ mod which uses a cheap arduino nano chip (I plan on installing that alongside the dbElec board). There's a thread for it over on assembler games.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 7:09 am 



Joined: 11 Dec 2014
Posts: 303
retrorgb wrote:
Look, if your solution worked for you, I'm happy for you. Most people would be content with an unmodified Genesis and it's RGB output is certainly much better then composite. The purpose of my site and discussions like this is to find ways to tweak consoles to get the absolute best out of them. I imagine most people wouldn't bother...but a lot of us here will do whatever is necessary to get the best picture possible. To directly address your post (with no attitude intended, just being blunt):

Most Genesis revisions output very noisy video and are far from "clean and crisp". To make things more complicated, there are MANY revisions of the Genesis motherboard and each have their own issues. There's no "just lift a pin" fix that applies to all.

That being said, two boards are being released soon that will be "universal" fixes to all Genesis issues; One uses the on-board encoder, the other uses a new one. I'll be testing both, but my guess is they'll be equal in quality and people would choose based on options and what fits their needs best.

Also, SNES is simple: Get a mini, connect RGB (the right way), done.

Most output noisy video? Pics to back that up?


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 8:07 am 



Joined: 05 Dec 2012
Posts: 411
tjstogy wrote:
Bob does either one have an IGR? It's a no brainer for people who use flash carts.

No, these boards stick to output. IGR would tap into a completely different set of chips.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 8:10 am 



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BONKERS wrote:
Most output noisy video? Pics to back that up?

Click on the db Electronics link above.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 9:41 am 


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FinalBaton wrote:
retrorgb wrote:
Unfortunately, in my opinion, the bottom line is that unlike SNES (just find a 1CHIP), in order to get clean video output from a Genesis, some kind of modification is required.

Excuse me but, can I get reasons as to why the Genesis' RGB signal supposedly need mods and RGB amp bypass and all that?

It's regarded as excellent AFAIK and if a cable with boosted sync doesn't fix the jailbars problem (which it did on my model 1 VA2), then you just have to lift a pin(did this on my model 2).

In my mind the SNES is the problematic one, requiring you to hunt down a very specific console revision, whereas all Gennys output clean and crisp RGB.


If you mean the color subcarrier pin, as I understand things that would mess up composite video. Fine for enthusiasts but not really "correct".


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 3:51 pm 


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Gotcha. Are these any different than arcade tvs board besides the mega amp?

retrorgb wrote:
tjstogy wrote:
Bob does either one have an IGR? It's a no brainer for people who use flash carts.

No, these boards stick to output. IGR would tap into a completely different set of chips.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sat Sep 17, 2016 6:26 pm 



Joined: 05 Dec 2012
Posts: 411
tjstogy wrote:
Gotcha. Are these any different than arcade tvs board besides the mega amp?

Yeah, a bit. I'll have a ton of details soon, but I'm just too busy to update the site for the next week or so. I should have everything up (including many pics demonstrating the issues & fixes) long before the boards go on sale though.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Sun Sep 18, 2016 6:01 am 


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Whether one console or another has the advantage on RGB, I will say this: I had to mod BOTH my Genesis and SNES in order to get the best possible RGB output. So to me, neither system is a winner in that regard.
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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Tue Sep 20, 2016 6:12 pm 


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Did a capacitor inventory of the Japanese VA0 Mega Drive 1 today, here is the list on the off chance anyone finds it useful:

I'm not sure about the C79 and C86 caps listed on most model 1 cap lists. This board seems to stop at C74, however there is a extra C1 cap on the daughter board so maybe that is actually C79?? Did I miss a cap? If anyone knows it'd be helpful.


Also, could anyone recommend suitable capacitors, I know Panasonic, Rubycon and Nichicon are the most popular, however there are so many series and variants of these brands it gets a bit confusing. Any help greatly appreciated! :)


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Tue Mar 14, 2017 10:18 am 



Joined: 13 Mar 2017
Posts: 1
Hello everyone,
this is my first post here and I hope I'm in the right section and everything... :)

I recently got a Mega Drive Model 1 (without "High Definition Graphics/ Stereo Sound" writing). As far as I can tell I think it's Motherboard rev. VA6.
I connect it to a 32" Philips LCD via Scart, using a cheap RGB cable from Amazon.
There were pretty bad Jailbars so I did some research and decided for the fix by lifting Pin 50 on the VDP because I couldn't see a trace connected to it anywhere (was planning on cutting the trace originally...).

I did that and it worked fine, Jailbars almost completely gone and the PQ overall seems even more crisp and bright than before.

Anyway here's my problem:
After doing the mod (VDP Pin 50 disconnected from PCB, now "hanging" there from the chip) I do get strange flickering on the screen.
Meaning the entire picture heavily distorts briefly, like the TV is trying to readjust or something. Sometimes only once and other times a few times in a row.
It happens very heavily after the console is turned on for a short time and kinda gets rarer after a while but still keeps happening every couple minutes.
Sometimes it's okay for a while and sometimes it's basically unplayable.

Now, I suspect it has something to do with sync.
Before doing the mod I was kinda worrying about sync because if I disconnected the composite signal (and since my cable was cheap I'm expecting to have sync on composite) how the TV would get a sync signal afterwards... but I went ahead anyway.

My question here:
Could this flickering come from using a cable that's not wired for composite sync or could it be that I did something wrong with the mod and maybe damaged something? Do I need to ground the Pin or can I just leave it dangling there?
I also kinda dented the pins next to 50 a bit (49 more so than 51), very little though... I hope it's not that.

Hope someone can shed some light on this. Best regards from Berlin, Chris.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Wed Oct 18, 2017 4:38 pm 


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Apologies for necro-bumping this thread, but I thought to do so, instead of creating a new one on the same subject.

Basically, after setting up the OSSC to get Line4x with my (unmodded) Japanese Mega Drive 2 / Mega CD 2 - and moving from fake scanlines to a pristine, unfiltered profile - I now notice prominent jailbars.
To be honest, they are faint with the optimal settings for 320x224 games (i.e. Sonic, Bare Knuckle...), but become quite distinct - especially on grey-ish/desaturated solid colors - in 256x224 optim. mode (so, Street Fighter II, Fatal Fury 2...).

I'm using an Euro AV RGB scart cable with sync on composite - which I bought a couple of years ago from thefoo83 (after hearing about his work here on SHMUPS), while I was still rocking my CRTs, and it worked perfectly since then - and I'm saying that because I'm a bit clueless about what is causing the jailbars in the first place.

I keep reading they are mostly common on the Mega Drive model 1 (not even all of them), and I'm having a hard time finding documentation on the issue with Mega Drive 2 consoles. To be honest, I don't even know if they depend on the RGB cable itself, on the console's chip, or on some faulty capacitor. To clarify, it's not a new occurrence. They've always been there, just masked up substantially by scanlines.

So, yeah, the question. :D
Any tip for someone like me who has no tools or technical expertise, about what's the best thing to do/look into, in order to fix the issue?

Thanks in advance guys! ^_-


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Wed Oct 18, 2017 5:28 pm 


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For what it's worth, it's preferable to bump an old thread than to make a new one. It keeps the older knowledge more accessible.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Wed Oct 18, 2017 6:13 pm 


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Voultar/Rene (DB Electronics) -- would either of you consider implementing Borti's IGR into your upcoming bypass boards?
https://github.com/borti4938/Switchless ... aDrive_IGR

It would be very helpful for those of us with everdrives-- as it is currently, the X7 is the only model that works with getting back to the main menu in game (and not for every game)-- however it doesn't work for master system games (in genesis) or 32x games. An IGR implementation-- similar to what is in Borti's N64 board-- would be siiiiiick. Thanks <3


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Wed Oct 18, 2017 6:47 pm 



Joined: 08 Mar 2017
Posts: 471
Regarding the jailbars, I'd really like to see what Voultar came up with for a fix.

If it uses the CXA1145 (which is great, should allow for a much cheaper solution!), then he has to get the RGB signals attenuated as required, and then routed to the CXA, shielded from all the noise in the region.
If that's not enough, something will probably have to be done to the subcarrier as well.

It sounds mostly like a construction and positioning problem + using some shielded cables.


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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Thu Oct 19, 2017 12:16 pm 


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rama wrote:
Regarding the jailbars, I'd really like to see what Voultar came up with for a fix.

If it uses the CXA1145 (which is great, should allow for a much cheaper solution!), then he has to get the RGB signals attenuated as required, and then routed to the CXA, shielded from all the noise in the region.


I recall hearing the approach was to completely circumvent the CXA1145 encoder (much like Voultar's RGB bypass board does for the SNES 1CHIP consoles). As such, I would expect the bypass board for the Genesis to tap into the lines coming from the VDP. At least with the VA2 and the VA3 consoles that I have, the subcarrier trace corrupts the blue channel with jail bars before it even gets to the CXA chip, which means an RGB bypass board would almost certainly have to tap into VDP side, but then maybe it can feed into the CXA and still use it so long as the original subcarrier trace is severed and re-routed.

On my VA3 that I use strictly for RGB, I surgically removed the entire subcarrier trace from the bottom of the board. It peeled off like a metallic masking tape, so the removal was clean as a whistle. RGB clarity now is absolutely perfect on it. MY VA2 has the trace routed through a toggle switch in case I have need for composite video.
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 Post subject: Re: Sega Mega Drive/Genesis Jail bars
PostPosted: Fri Oct 20, 2017 6:46 pm 



Joined: 08 Mar 2017
Posts: 471
Apparently, there is no quality problem with the 1145 itself. It's all just bad attenuation / level adjustment by SEGA.
https://twitter.com/Voultar_Modshop/sta ... 7792670721

The board appears to redo this section with different value components:
Image

I'd like to build this myself, but there are no details from Voultar yet.


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