GBS 8200/8220 CFW Project

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Nuck-TH
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Re: GBS 8200/8220 CFW Project

Post by Nuck-TH »

rgn11 wrote:Greatly appreciate if anyone could answer some of these questions I've had:

1) I believe I already have a sync strike lying around. Does this mean I don't need the 100ohm resistor to sync and ground since I'll be using the VGA output from the sync strike to the VGA input on the GBS?

2) I have the GBS board revision with one VGA output and black buttons (as an aside, it looks exactly like the 1 output 8200 models to me, but mine is branded the HD 9800 for some reason); so if I don't need the resistor, I assume the only applicable mods are the power supply bypass capacitors and C11 removal? Is the ferrite bead preferable to removal of C11?

3) Also, for those that own both the OSSC/GBS, does anyone have any comparison comments or images; I bought the GBS years ago as a budget option before the OSSC was around, and I'm wondering about the comparison.

4) Lastly, I can seem to find many images of people's completed wiring; does anyone have a closeup of a fully modded board?

Thanks for any answers.
1) Yes, i reckon with sync stripper resistor is not needed.

2) Before you start mods, check image quality first. If there is no noise, so mods are not needed. I have two such boards and apparently on one mods either didn't remove noise, or even created it. Second have just wemos connected and picture is noiseless.

3) I don't remember side-by-side comparsions around here, but assuming gbs price - quality is quite good. Frame lag is same or even less than on OSSC.

4) There is nothing much to picture. 5 wires to wemos/nodemcu is no rocket science. There is "wiki" on gbs-control github with setup instructions.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Hey,

I second everything Nuck-TH just said, except that I would install the 100 Ohm resistor.
My reasoning is that the SyncStrike probably is made for connecting to TVs, which have the ~75 Ohm termination.
The Strike's manual will tell you for sure!
rgn11 wrote:Is the ferrite bead preferable to removal of C11?
C11 should be removed to avoid the regulator (IC5) oscillating.
I think I only ever mention a ferrite bead when dealing with the output amplifier on the first revision GBS board.

Ryoandr:
Yeah, I know I drive the contrast too much with scanlines. It doesn't appear too bad on LCD, but it's overdriven there as well.
Soft scanlines inherently take a lot of brightness away, and that's hard to compensate for.
Try the 3_35 register to adjust contrast (example: s3s35s20 where 20 is the value).

retromaniak:
You don't have to worry about wrongly deinterlacing content with gbscontrol. I can very reliably tell whether a source is interlaced or progressive.
The software will automatically enable deinterlacing only for real interlaced content.
It would be trivial for TV manufacturers to implement this as well, just by the way :p
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Syntax
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Re: GBS 8200/8220 CFW Project

Post by Syntax »

rama wrote: retromaniak:
You don't have to worry about wrongly deinterlacing content with gbscontrol. I can very reliably tell whether a source is interlaced or progressive.
The software will automatically enable deinterlacing only for real interlaced content.
It would be trivial for TV manufacturers to implement this as well, just by the way :p

My LCD TV for some reason sees line doubled/deinterlaced 480i as 480i.... Then it tries to deinterlace it....
When im using DCHDMI I use passthru on the deinterlacer and the picture looks awesome, else its a shakey double deinterlaced mess.
I havent tested this TV with GBS, it could just be an issue with the DCHDMI and my HDMI input.
rgn11
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Re: GBS 8200/8220 CFW Project

Post by rgn11 »

rama wrote:Hey,
My reasoning is that the SyncStrike probably is made for connecting to TVs, which have the ~75 Ohm termination.
The Strike's manual will tell you for sure!
Thanks to both of you for your help. So to gather more information, I connected my Saturn>SCART switch>SyncStrike>Stock GBS>Extron VGA switch>Old plasma TV VGA input, and I do get a normal picture. I couldn't find a manual but I read there is no amplification of the video signal done by the syncstrike. Does this mean my TV's VGA input can handle non-75ohm-terminated sources, or perhaps something else in my chain is terminating the signal properly? Do I still need the resistor in this case? Thanks very much.

Also, my mistake about the ferrite bead, I was actually asking about the C11 removal alternative which is replacing C11 with 16V, 22uF tantalum bead cap.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Termination happens at each receiving station. The Sync Strike has it on the input, the GBS has it on the input, etc (TV as well).
We're only concerned with the GBS input termination and the question is whether the Sync Strike outputs a signal too strong for the GBS to handle or not.
I would just install the 100 Ohm resistor. If it works, all is well. If it now doesn't want to sync anymore, the resistor needs to be removed.

I wouldn't bother with a tantalum capacitor.
Sure, it's the best possible part for the job, but any 22uF electrolytic will do fine.
Even no capacitor at C11 is fine, since there is an electrolytic on the line.
The only thing that's not good is that default SMD capacitor.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Maybe this video will help.
I was surprised that someone put out such a nice video on gbscontrol! :)

https://www.youtube.com/watch?v=_Tnf6q7zsEU
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NoAffinity
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Re: GBS 8200/8220 CFW Project

Post by NoAffinity »

Rgn11, post #1859. I posted pics of my wiring. As simplified as I could get it with basic soldering and wiring.

Maybe I'll try to put together some side by side shots of ossc vs gbs this weekend. But the way I would describe the difference is:

Ossc with optimal timings perfectly dialed in allows you to get a pixel perfect extremely sharp and perfectly multiplied image.

Gbs does not get quite as sharp but still gets very sharp and looks great. Gbs is much more plug n play across all sources.

We verified a while back that input lag (or lack thereof) is effectively the same between the two.

Sent from my SM-G955U using Tapatalk
rgn11
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Re: GBS 8200/8220 CFW Project

Post by rgn11 »

NoAffinity: That's neat work going under the board. That's mainly what I was looking for, just ideas for different wiring setups and ESP8266 location for least interference. I think I'll do something similar. I was going to use jumper wires and pin headers so I could remove it to update, but is it possible to update it over WiFi using the Arduino IDE?

I've been having a hell of a time trying to find anyone making cases for the GBS besides the 3D print plans, which can get expensive if you don't have a printer already. I'd like to find one of those clear acrylic top and bottom panels at least but can't find anything so far. I think I'll do what you did too and use those PCB feet if I can't find anything, just to get it off the ground.

rama: Thanks that was a helpful video; I had gathered a lot of it from reading as much of this thread as I could and the wiki, but this was helpful to see it all the way through.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

So just a small update on the 1nF SOG coupling capacitors:
I've seen 2 different behaviours with them installed now. While one board is a little unstable with them, the other works perfectly fine.
It's even more reliable than an unmodded board, allowing the maximum SOG level even on Composite Video.

So I don't know.
I guess if you have the mod, try to keep it and see if your sources work.
This only affects scaling mode with RGB + Composite Video Sync, by the way.
If you use a sync stripper, luma or CSync, it shouldn't make a difference either way.
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

I've toyed a bit with the s3s35s register, so if I understand correctly there's a +0x30 boost (I got 0xb0 value with scanlines). I think a 0xa0 works great with VGA CRTs, or even 0x98 if your CRT is bright, which would equal to a boost between +0x18 and +0x20.
I really like +0x18 personally.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

I just changed the method in the development branch. It's using the "white expansion" feature now, which seems to work a little better.
But this also has a gain knob to tweak, if you want ;)
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

I just updated and now I get jumpy screen and stutter :/ or sometimes blank screen...
Also, I think the knob isn't in the web page.

Arduino got a lot more verbose for some reason too, I get the raw data displayed while uploading and it feels slower...

EDIT : ok so, MD console and consolized MVS work fine, they either use luma or csync (the MVS uses csync for sure).
it's the MVS with supergun that has trouble, it uses an MD2 cable wired with CVBS (it's the only one I have ATM, I have a csync one coming soon).
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Oh, "knob" just means there's a register that can be tweaked.
It's not in the web ui, mainly because I don't have dials / slider controls yet.

When your MVS is unstable, try first disabling syncwatcher ("m" command or use the button in the web ui).
Next, try sending "t5t3et4" and see if it now becomes stable.
If not, try sending "t5t3et5" and check again.
If both don't work, it's probably a strong colorburst. In that case, try different SOG slicer levels with "wsog x", x from 4 to 15.
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

Only wsog 15 cured it completely. Anything lower still showed some screen jumping.
Shiver_169
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Re: GBS 8200/8220 CFW Project

Post by Shiver_169 »

rama wrote:So just a small update on the 1nF SOG coupling capacitors:
I've seen 2 different behaviours with them installed now. While one board is a little unstable with them, the other works perfectly fine.
It's even more reliable than an unmodded board, allowing the maximum SOG level even on Composite Video.

So I don't know.
I guess if you have the mod, try to keep it and see if your sources work.
This only affects scaling mode with RGB + Composite Video Sync, by the way.
If you use a sync stripper, luma or CSync, it shouldn't make a difference either way.
Hi, my last update was when the 1080p resolutions were added and I made the mod of the capacitors. Undoing it makes it quite complicated for me to even ruin a board when I try it. The question is whether the update will have problems right now everything works very smoothly. I also have the sync separator done I removed it when I made the Mod now I do understand well if I have the Mod done and added the sync separator for the sources that are composite video, it would work perfectly not? I await a response before doing Update.
tbender
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Re: GBS 8200/8220 CFW Project

Post by tbender »

I have gbs-control up and running. I did the capacitors in parallel, SOG cap replacements, and C11 removed. It's looking great so far with my Tag1 board via VGA with one exception: The picture blacks out every few seconds.

Here's how it looks.

If I turn Framelock OFF, it stops exhibiting this problem. The alternate mode doesn't improve it.

I've been playing with it off with no problem but I share anyway if it's fixable, etc. I can report extra info if necessary.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Well, one thing is that you can always downgrade to every commit ("version") ever made.
So it's never a one way decision.

I would just try the new code and see if it runs.
As I said, I have one board that has some issues with the 1nF caps, and one board that works exceptionally well now.

Ryoandr:
That sounds like your CVBS Sync comes in too strong, ie: The source is sending non-standard / not meant for TVs directly.
That, or the termination resistance is too high. Is the 100Ohm resistor installed?
Shiver_169
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Re: GBS 8200/8220 CFW Project

Post by Shiver_169 »

rama wrote:Well, one thing is that you can always downgrade to every commit ("version") ever made.
So it's never a one way decision.

I would just try the new code and see if it runs.
As I said, I have one board that has some issues with the 1nF caps, and one board that works exceptionally well now.

Ryoandr:
That sounds like your CVBS Sync comes in too strong, ie: The source is sending non-standard / not meant for TVs directly.
That, or the termination resistance is too high. Is the 100Ohm resistor installed?
I'm quite new in this you can give me the commit where the update of the web interface was uploaded in case you want to do the Downgrade I really do not know where these commits are stored.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Sure. It is a bit weird to get to older states :p

First you pick a commit that might be close to what you want to downgrade to:
https://github.com/ramapcsx2/gbs-contro ... 9b35e8d+34

In this case, I choose this one here (Hope the links work):
https://github.com/ramapcsx2/gbs-contro ... 18380ac0c2

To the right, there is a "Browse files" button that, when clicked, leads us to the "tree view":
https://github.com/ramapcsx2/gbs-contro ... 18380ac0c2

And here you can "Clone or download > Download ZIP" the project exactly as it was in that point in time.
The underlying Git versioning software is quite amazing in that regard :)
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

Rama, the encoder on the supergun is a BH7236. It worked on the previous dev build (before the scanline change). As far as I can tell with my cheap scope, the levels are correct (with 75R termination).
I have the 100R termination on the GBS, however note that the input resistor isn't 500R as mentioned on the wiki. My 1st board has a 1K and my 3 newer boards (2 vga V4.0 and 1 hdmi) have 2.2k, which leads to a slightly higher termination around 91R or 95R, higher than the expected 82R.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Yeah, that's nothing (the termination difference).
The problem must be with the SOG ADC or the external components.
Do you have the first revision GBS by chance?

I'm currently working with a stubborn board. No matter what kind of SOG coupling capacitors used, its slicer level range is very narrow.
This makes it really annoying to try and deal with it in code, but I'm slowly progressing at least ><

Note that I'm aware that previous versions deal with these board better.
i never even attempted to set a proper slicer level then, which led to all kinds of different issues.
So I really want to continue with the current, more proper setup.
It should work well on all boards eventually.

If you can tweak your scope to show this:
Try and trigger on the negative sync tip, then display various brightness levels / colors with some game.
The color burst and active video should always stay some 100mV above the Sync tip.
Some really old systems (for example: Master System) often dip even below the sync tip level.
If I couldn't H-coast around this, they would never be able to sync.
Systems with such strong color information "noise" are the hardest to work with, and I really suggest just using a sync stripper for them.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

This is what I mean (Phantasy Star on a Mega Drive)

Image Image
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

All my 3 VGA boards are V4: black buttons, small inductor in voltage regulation area. The 4th is an HDMI that looks much like a V4 too.

On a side note, I received my csync MD2 cable (with 470R and 220µF on the line as expected), works perfectly with MD2, but the supergun has the csync pin wired to BH7236 pin 11 (syncout). Direct connection to monitor showed a top screen skew, while the GBS couldn't sync. Since the datasheet states this pin as a terminal, I believe it is unfit for driving a 75R line. So I managed to wire the socket pin to the output of the LM1881 higher in the chain, and it worked, no more skew and GBS syncs good.

Honestly, if it was just for me I can just feed clean signals but I might give one so I want the least worries possible. You know, refit an LM1881 on the board might just be the solution.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

You could install an 1881, or test the board beforehand. It seems the stubborn boards aren't that many overall.
rgn11
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Re: GBS 8200/8220 CFW Project

Post by rgn11 »

@rama: I still need to do the 100ohm sync to ground resistor on P11 if I only use VGA input right? Do I also need to do P3? Thanks.
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Rgn11,
it depends on the source.
Every home console or other consumer equipment that's meant for TV: Install the resistor
PCs or older home computers: It further depends on what kind of sync they provide and what the signal level is

Without going into signal levels too much, the 100 Ohm resistor can load the source more, though I don't think it would cause issues.
So I recommend you install the resistor for these sources as well.
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maxtherabbit
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Re: GBS 8200/8220 CFW Project

Post by maxtherabbit »

rama wrote:Rgn11,
it depends on the source.
Every home console or other consumer equipment that's meant for TV: Install the resistor
PCs or older home computers: It further depends on what kind of sync they provide and what the signal level is

Without going into signal levels too much, the 100 Ohm resistor can load the source more, though I don't think it would cause issues.
So I recommend you install the resistor for these sources as well.
if you are only using TTL level (or even 3.3V LVTTL) c-sync or separate h/v on VGA the resistor would be 100% not needed, correct?
rgn11
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Re: GBS 8200/8220 CFW Project

Post by rgn11 »

rama: Yeah I'm going to use the resistor as I have no other sources except home consoles (fed through a Sync Strike with VGA out to the GBS' VGA in), but I was wondering if P11 and P3 are the correct locations for a VGA source (so two resistors), or if only P11 is necessary.

Phrased more simply: where do I place the sync to ground resistor(s) for the VGA input on the GBS?
rama
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Re: GBS 8200/8220 CFW Project

Post by rama »

Rgn11:
P3, P11 and the VGA connector are all the same circuit. It's just broken out to different connectors for convenience.
So just one resistor is required. I usually wrap it around the "S" and "GND" pins on P3.

Maxtherabbit:
That's correct. The factory termination is for LVTTL levels, so no extra resistor is required.
Final judgement on TTL (5V) signals into the 3.3V device is still out.
I'm developing with TTL into the GBS and so far I haven't had issues.
The device could be 5V tolerant, or it may be 3.3 + 0.3 maximum.
It's up to you to decide whether you take the 5V risk or not.
If not, you need additional series resistors on H and V.
Ryoandr
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Re: GBS 8200/8220 CFW Project

Post by Ryoandr »

forgot to mention because of all that sync testing, but the new scanlines are indeed very nice.
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