GBS 8200/8220 CFW Project

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ashwinjio
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Re: GBS 8200/8220 CFW Project

Post by ashwinjio »

I just tested the Digispark Pro adaption on an Arduino and it worked pretty well.
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Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

Hey all, I've just completed my GBS-Control mods & am having an issue with the clock generator, hoping someone can help.

I have followed the github instructions, added a cap to C11 & everything else that was required.

Without the clockgen installed, I get a solid image and tbh I don't notice any screen tearing.

With it installed, I get a horrible wobbling image, like vertical waves runningup/down the screen, especially on sides of the screen. On low res (480p), there is only a slight wobble & gets worse the higher up you go, 720p is a bit worse & 1080p is really bad. This happens on all inputs, RGBs and component.

I've checked & double checked my install. GBS-C (via web interface) knows there is a clockgen installed, so any other ideas?

At this point I'm thinking to completely remove it & not bother.
Hapimp
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Re: GBS 8200/8220 CFW Project

Post by Hapimp »

Hi I’m getting ready to build and have easy access to the Adafruit boards. Were you able to confirm this theory? And if so, could I trouble you for some pictures of what exactly to remove? Thanks, hope this worked out.
stj wrote:i just got my clock-gen pcb delivered and looking at the schematic i think i see why they arent reliable.
this is only theory till my next post, but here goes.

the board has a 3v3 regulator and 5v input level shifters on the I²C pins.
but the GBS and the ESP are native 3.3v.
so this crap can degrade the signals and cause a voltage drop.

i intend to desolder the regulator, the 2 10uf caps, and all the level shifting stuff from mine before i install it.
i'll post back in a few days after i'v tried it.
i also have a frequency counter and scope, so if it doesnt work i can see if these purple boards have faulty parts on them.
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

Has anyone got any idea what could be causing this wobbling?

Recorded at 480p.

https://i.imgur.com/PzArMcv.mp4

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NoAffinity
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Re: GBS 8200/8220 CFW Project

Post by NoAffinity »

A) low quality power supply
B) what's that added capacitor over on the left, by the inputs and the source of power for the clock gen board? Looks like possibly the ceramic cap where clock gen power is tapped was replaced with an electrolytic?
C) is the 100 ohm resistor installed between sync and ground? And what is your input connection?

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

Post by Dreamcazman »

NoAffinity wrote:A) low quality power supply
B) what's that added capacitor over on the left, by the inputs and the source of power for the clock gen board? Looks like possibly the ceramic cap where clock gen power is tapped was replaced with an electrolytic?
C) is the 100 ohm resistor installed between sync and ground? And what is your input connection?

Sent from my SM-G955U using Tapatalk
A) Tried multiple PSUs, now using a known good 12v 4A one.
B) I saw it on one of the tutorials, the caps were supposed to be SMD type & piggybacked onto the one's that were there, but I only had electrolytic caps available.
C) Not at the moment, I had it connected when I started the mod but removed it as it didn't appear to make a difference. This current connection is RGBS from my MD2, but the wobbling also occurs with the OG Xbox connected via component.

Like I said previously, without the clockgen it's rock stable but I have the potential for image tearing.
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Josh128
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Re: GBS 8200/8220 CFW Project

Post by Josh128 »

The wire from the CLK0 pin looks too long. Isnt that the one that is very length sensitive according to the documentation? Try moving your clockgen board closer to the pin where thats connected, you should be able to cut that length in half if not more.

https://imgur.com/5JQEZF7
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

Josh128 wrote:The wire from the CLK0 pin looks too long.
Ok, I'll try shortening that & let you know, thanks!
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NoAffinity
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Re: GBS 8200/8220 CFW Project

Post by NoAffinity »

5v power supply

Get a ceramic cap and replace the electrolytic

Shorten the clock gen wire as noted

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Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

I shortened the CLK0 wire & also tried a 5V/2A PSU, no difference.

I don't have any ceramic caps so will grab some next time I go to the electronics shop.
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Josh128
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Re: GBS 8200/8220 CFW Project

Post by Josh128 »

...
Last edited by Josh128 on Fri Mar 25, 2022 11:28 am, edited 1 time in total.
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Josh128
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Re: GBS 8200/8220 CFW Project

Post by Josh128 »

Its possible you have a defective clock generator board. I installed mine as shown with no extra caps or resistors whatsoever and it was rock solid from the first power on.
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

Josh128 wrote:Its possible you have a defective clock generator board. I installed mine as shown with no extra caps or resistors whatsoever and it was rock solid from the first power on.
Yeah, I'm starting to think the same. I bought mine locally which incurred a price premium (wanted it quickly) so I might just grab one of the purple ones from China.
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Gunstar
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Re: GBS 8200/8220 CFW Project

Post by Gunstar »

Electron Shepherd is looking for some beta testers for their HDMI module:
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Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

That looks cool, much neater implementation!

I'd like to be a tester, but I don't live in the US.
twotone8
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Re: GBS 8200/8220 CFW Project

Post by twotone8 »

I've been on the lookout for a nice HD15 to HD15 passive sync combiner to use with the GBS-C Downscaling functionality, and it appears that noone sells one off the shelf.

The HD152SCART would work, and I hope to snag one when they're next available.

For now I've just been using a cheap HDMI to Component converter box, which side-steps needing to convert RGBHV to RGBS.

I was looking around ebay and I found this listing:
https://www.ebay.com/itm/304376184172?h ... Sw-bxiHGRF
One of the GBS-C AIO models, but with a curios addition in the description:

"The rgbhv downscaling bug has been fixed on this model"

Does anyone know what that might be referring to? Is it possible that the seller included a passive sync combiner with this unit?

edit:
Heard back from the seller:
"Yes you are correct, I put an internal sync combiner into the scaler on the db15 in port. So no need for adapter."

I wonder what that looks like.
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

twotone8 wrote:I've been on the lookout for a nice HD15 to HD15 passive sync combiner to use with the GBS-C Downscaling functionality, and it appears that noone sells one off the shelf.
Have you tried making one using a few resistors & a transistor?

I made one of these up & works great on my TV.

https://www.retrorgb.com/building-a-pas ... biner.html
https://www.cathoderayblog.com/converti ... s-control/
sharak
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Re: GBS 8200/8220 CFW Project

Post by sharak »

twotone8 wrote:I've been on the lookout for a nice HD15 to HD15 passive sync combiner to use with the GBS-C Downscaling functionality, and it appears that noone sells one off the shelf.
I have exactly this problem, and getting hold of transistors and bits, is a bit too difficult for me at the moment. I would love a small off the shelf dongle... I want a 15 kHz option with this thing and it's such a shame it doesn't work.
Sparda1418
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Re: GBS 8200/8220 CFW Project

Post by Sparda1418 »

Anyone knows why I get wavy lines across the screen when only using 480p? Tried different PSU from routers and it’s always the same result. I’m using VGA CRT. I haven’t replaced any capacitors and I’m using HD Retrovision component cable. Any help would be appreciated.
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

Dreamcazman wrote:
Josh128 wrote:Its possible you have a defective clock generator board. I installed mine as shown with no extra caps or resistors whatsoever and it was rock solid from the first power on.
Yeah, I'm starting to think the same. I bought mine locally which incurred a price premium (wanted it quickly) so I might just grab one of the purple ones from China.
UPDATE - ALL FIXED!

Got the new clock gen and 0805 10uF caps and installed them, the image is now solid as a rock!

So the issue was most likely caused by a dodgy clock gen, phew. I'll see if I can return it for a refund, don't like my chances though.
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Gunstar
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Re: GBS 8200/8220 CFW Project

Post by Gunstar »

Sparda1418 wrote:Anyone knows why I get wavy lines across the screen when only using 480p? Tried different PSU from routers and it’s always the same result. I’m using VGA CRT. I haven’t replaced any capacitors and I’m using HD Retrovision component cable. Any help would be appreciated.
I believe the cap mods will help with this.

@Dreamcazman Nice, seems a few people are getting dodgy clock gens! Hope you get your refund
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Josh128
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Re: GBS 8200/8220 CFW Project

Post by Josh128 »

Dreamcazman wrote:
Dreamcazman wrote:
Josh128 wrote:Its possible you have a defective clock generator board. I installed mine as shown with no extra caps or resistors whatsoever and it was rock solid from the first power on.
Yeah, I'm starting to think the same. I bought mine locally which incurred a price premium (wanted it quickly) so I might just grab one of the purple ones from China.
UPDATE - ALL FIXED!

Got the new clock gen and 0805 10uF caps and installed them, the image is now solid as a rock!

So the issue was most likely caused by a dodgy clock gen, phew. I'll see if I can return it for a refund, don't like my chances though.
Nice man, gladd to hear it!
TomDD
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Re: GBS 8200/8220 CFW Project

Post by TomDD »

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Josh128
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Re: GBS 8200/8220 CFW Project

Post by Josh128 »

Very nice, thanks for this!
coredump
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Re: GBS 8200/8220 CFW Project

Post by coredump »

So, I got the GBS-C working and all for VGA upscale. I was trying downscale from PS2 480i to 240p on a PVM and the colors got all messed up. I get the right colors on upscaling to VGA, and the PS2 output in component also works fine. THis is the chain:

PS2 Component cable -> Extron MVX -> GBS-C component input -> VGA adapter to component -> PVM

IS there any setting or mod that I am missing here?
Guile
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Re: GBS 8200/8220 CFW Project

Post by Guile »

coredump wrote:So, I got the GBS-C working and all for VGA upscale. I was trying downscale from PS2 480i to 240p on a PVM and the colors got all messed up. I get the right colors on upscaling to VGA, and the PS2 output in component also works fine. THis is the chain:

PS2 Component cable -> Extron MVX -> GBS-C component input -> VGA adapter to component -> PVM

IS there any setting or mod that I am missing here?
This is unfortunately a bug with the gbs-c code. If you toggle the resolution it should fix the colors but it can happen again. It seems to happen when the screen goes blank.
Dreamcazman
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Re: GBS 8200/8220 CFW Project

Post by Dreamcazman »

coredump wrote:I was trying downscale from PS2 480i to 240p on a PVM and the colors got all messed up.
Does the PVM have RGBS or RGBHV inputs? You could try a DB15 (VGA) to RCA/BNC connector cable, maybe it's something to do with the conversion back to component.

Not sure if that bug Guile is referring to will affect this.
Lamaman1971
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Re: GBS 8200/8220 CFW Project

Post by Lamaman1971 »

Hi Folks, wondered if anyone might be able to give me some advice? My GBSControl works great but my clock board doesn’t respond when I toggle it in the gui. It has power and I have checked my connections - same problem. I have tried an alternative clock board and it’s the same.

I am obviously doing something wrong - not sure where to start checking - has anyone got any ideas?

Thanks, Mark
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digitron
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Re: GBS 8200/8220 CFW Project

Post by digitron »

Is there a way to verify the clock generator is functioning outside of having a stable picture?

Guessing I could put a logic probe on the signal line or something..

Also looking for a cheap case recommendation that will fit a NodeMCU off to the side.
TomDD
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Re: GBS 8200/8220 CFW Project

Post by TomDD »

I've created a little breakout PCB for a SCART socket giving access to RGB, Sync, Ground & Audio L/R, making it easier to wire it all up. These all fit in my latest case design which you can get at https://www.thingiverse.com/thing:5363666

If you are interested in the PCB I popped a few on eBay.

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