GBS-8220, 23DB Connectors and Leads

[rabidgerry]

Originally Posted by psoma

Yep, bingo! Fingers crossed

The resistor trick I was referring to was based on a post Dave Haynie made in 1994 first discussing the issue (Higgo referenced it). He suggested "putting a 100 ohm resistor across pins 15 and 13 on the Amiga side" but it did nothing for me... it did however get me investigating this particular fix.

Good luck man!

Ahh I see!

Ok just wanted to know what kind of enclosure have you put your cards into?

[Higgy]

I just mounted mine on a bit of thin board using copper stand offs. Then I mount them to the VESA mounting on the back of the monitor. No need to access them.
Then I have a female Scart block (i buy scart couplers and then remove 1 of the female connectors) that features a sync splitter (although it is not now needed with gbs control) and a 3.5mm Jack for audio out. Then I can just plug any RGB system into it.

[rabidgerry]

Originally Posted by Higgy

I just mounted mine on a bit of thin board using copper stand offs. Then I mount them to the VESA mounting on the back of the monitor. No need to access them.
Then I have a female Scart block (i buy scart couplers and then remove 1 of the female connectors) that features a sync splitter (although it is not now needed with gbs control) and a 3.5mm Jack for audio out. Then I can just plug any RGB system into it.

I really like the little boxes you see online for the GBS boards but some people are charging a fortune for them. I think the boxes I had a link to in this thread might just be a good alternative.

@psoma
On my Amiga it appears the resistors are in a different locations again. Slightly further to the right. Can you verify these are the correct resistors highlighted yellow in the photo?

[Stedy]

Originally Posted by rabidgerry

Ahh I see!

Ok just wanted to know what kind of enclosure have you put your cards into?

Have you got a 3D printer or access to one?

https://www.thingiverse.com/thing:4286979
https://www.thingiverse.com/thing:3562194
That's two neat case designs that allows for the board and the ESP8266.

[rabidgerry]

Originally Posted by Stedy

Have you got a 3D printer or access to one?

https://www.thingiverse.com/thing:4286979
https://www.thingiverse.com/thing:3562194
That's two neat case designs that allows for the board and the ESP8266.

That box is awesome!! But I do not have access to a 3d printer. And to think I passed on one my uncle was going to give me. Couldn't get to one during all this lockdown madness either

Well I did the mod and I think I did it pretty well (it was dam tricky) but it didn't seem to do anything. Might I have done anything wrong?

[psoma]

Hah - OK... you must have a Rev 2 board. Looks like on a Rev 2 board, the PIXELSW and CCK_B signals are the same way around as the 600.

Sorry mate. So, your first diagram was right for your model. Just take the GND wire off the left-hand resistor and solder it to the bottom of the righthand one.

Doh!

[rabidgerry]

Originally Posted by psoma

Hah - OK... you must have a Rev 2 board. Looks like on a Rev 2 board, the PIXELSW and CCK_B signals are the same way around as the 600.

Sorry mate. So, your first diagram was right for your model. Just take the GND wire off the left-hand resistor and solder it to the bottom of the righthand one.

Doh!

Ok I had a feeling you were going to say that/ All the previous images I had posted were from mother boards I used online for demo purposes, but the last 3 photos have been from my actual mother board which is a rev
2.0B board so yes you are right I will swap the ground wire over and see if it makes a difference.

Obviously I had to dismantle my Amiga to do this mod, well since putting back together I now have an issue where my floppy drive only reads the disks 50% of the time. Disks I was trying were new (as in new old stock). Never had an issue before with the floppy drive and I know it's ancient but I would very much like to have it working again. Only thing I did was take it out and hoover dust out of it. Anyone any thoughts? I realise it's off topic, but since it happened doin this mod I figured I'd throw it out there before I have to start a new thread.

Weirdly the hard disk light started to work as well (another issue I have a thread about ). This was briefly until I tried to use the floppy drive again to make sure that LED was working and of course it was, but that is when I discovered that the floppy was reading the disk 50% of the time and coming up with NDOS?? the other 50%. Then the hard disk LED stopped working again

[rabidgerry]

Well I swapped the wire about........................AND HELL FUCKING YEAH!

NO VERTICAL LINES

And randomly the floppy drive read about 15 different disks in a row so I dunno what the issue was there. I am so pleased about this result! No vertical lines, cannot believe it!!

Thankyou so much @psoma

[psoma]

Thanks awesome news man! I remember jumping for joy when I first sorted it out too. Guess I better update my original post .

I think this is one of those situations where the GBS is unfairly blamed for an imperfection actually being generated by the Amiga. With the vertical lines gone, the picture is excellent... right up there with FAR more expensive scan doublers.

Did you have the case on while testing the floppy? I've seen issues where the lid hasn't been on properly and the eject button gets caught on the case slightly preventing the disk from sitting in the correct, head aligned position. Anyway, all's well that ends well!

[rabidgerry]

Originally Posted by psoma

Thanks awesome news man! I remember jumping for joy when I first sorted it out too. Guess I better update my original post .

I think this is one of those situations where the GBS is unfairly blamed for an imperfection actually being generated by the Amiga. With the vertical lines gone, the picture is excellent... right up there with FAR more expensive scan doublers.

Did you have the case on while testing the floppy? I've seen issues where the lid hasn't been on properly and the eject button gets caught on the case slightly preventing the disk from sitting in the correct, head aligned position. Anyway, all's well that ends well!

I spoke too soon! Ok so the lines have gone away on most instances but I think they are either their or coming and going sometimes with certain colours.

When I tested earlier I literally powered the machine on and looked at the workbench background (where vertical lines could be seen usually) and I think tested Supercars out (where I see them a lot on the track). Looked to be gone.

However I think it would be fair to say they are still kind of there in Supercars and that's obviously on the grey track. Dare I say there is a bit of noise at times as well? I dunno, not entirely sure, I'm detecting weirdness and I dunno if it's my machine or the GBS board. My solder joints all seem fairly good (man that was tough) to the mother board, so I'm assuming I'm making good connection. Any ideas as to what I might be experiencing?

My machine is also in need of a re-cap and I think I might try that this afternoon. No ideas if that would help or not or improve anything other than the life of the machine.

I definitely think the lines have improved greatly. I mean say 80%, but I'm either hallucinating and they are there still, or else they are coming and going. I'm pretty positive they were gone completely last night but came back on and off and now they are just there subtly, even more than before. Playing some completely different games though and the picture is perfection. As you say, the board is capable of much more expensive results. My board was £14, I cannot argue with that. I guess now I've edged closer and closer to near perfect I'm desperate to get it 100% Yip I know!

Still though totally appreciate the tips and direction, it definitely helped. What exactly does the mod do and how did you come up with it?

Oh and the floppy drive, I think you are correct because I noticed the eject button not coming out as much as before and behaving a little differently! Think it's ok now though.

[psoma]

So I too still have some VERY faint vertical lines. I can't tell if they're from the GBS or Amiga. Definitely 100x better than without the mod though, for if I remove the ground wire, it's super obvious again.

Depending on your model GBS, it *could* be interference affecting that directly. There are a couple of additional mods that can be completed to the GBS itself to fix this (8-Bit guy did a video on it).

As far as this mod itself... it was just trial and error around the CCK signal. I had a feeling it was the clock leaking onto the signal lines and figured grounding it prior to reaching the cable would help. Some may still be leaking there though, so I'm actually going to bite the bullet and remove the CCK resistor completely isolating it to see how that goes.

[rabidgerry]

Yes it's definitely an improvement. I think now I'm just finding other stuff wrong which is GBS related, it's hard to tell. I almost want to take the mod apart again to see the original lines lol. No it definitely has helped. I think there is actual weirdness happening with movement on screen in my case, that's my theory at the moment. In Supercars I think I see the vertical lines more as I move about the screen. I dunno it's hard to tell. I did do one mod today that improved colour (and it really wasn't bad before with all variable resistors to the max) which was to remove the RGB pots and hard wire them. This gave a lot more richness to the colour.

Not sure what's left to try or if any of the issues are GBS, my Amiga or my home made cable what is apparently a ground or two short (there is not other ground to solder from the cable).

Looking for 8 bit Guys video. You done any of his mods?

Also how to you run the GBS control? Ram speed, options, over sampling rate etc? I play about with these and then can't make up my mind what is better.

[psoma]

So I have one GBS8220 v3 and 2 x GBS8200 v5. I find the v3 provides a more stable picture than the v5s - the v5s occassionally get horizontal glitches which seems to settle as they warm up. Could be the linear vs switching power regulator but I'm not sure. They all still have faint vertical lines which I'd love to get rid of but the wire fix to the 600 has moved that to the back of the priority list as I find it isn't jarring now at least.

As far as mods go - I've removed the C11 caps. I've replaced it with a 22uF on one of the v5s but can't really comment as to whether it has helped... I never had issues with white speckles which this apparently fixes. I also tried the copper tape on the back of the board but this actually made interference worse. It was before I removed the clock signal from the input though, so I may try it again but need some new tape.

GBScontrol wise, I'm running it pretty vanilla. 1280x1024 on all 3 (native res of my 3 x 19" screens) - 2 are de-interlacing as I'm running hi-res laced, whereas the 3rd is running standard-res progressive. I think the de-interlacing causes a few glitches which I can excuse... it's a tricky process. Only other changes are size and position to fit to screen which in itself is a bit of a challenge.. you set WB fine, and then run a game like ProjectX and half the stuff is off screen.

Will keep plodding away with it and report back with anything else I find.

[desiv]

I have something quirky I noticed on my 1200 with a GBS-8200.
A bit of history, I had a previous GBS for years, but it died. Not too long ago, I got a replacement and thought it was fine.
But then I noticed some games weren't displaying on my VGA monitor.
Now, I was having some monitor issues, so I thought it was just that monitor having problems.
But got another monitor and the same issues... And then I ran down the issues...
(To be fair, I can't remember if I had this issue on the original monitor, and it is dead now)

My GBS will only display on my monitors in PAL.
When I go to anything NTSC, the monitor won't display it...
I also tried going into early boot mode, and yep.. No display by default. Hit space to get into PAL, and the screen displays.

I am thinking, it could be that the newer monitors just don't like NTSC (or the refresh rate)?
I generally run my Workbench in PAL and a lot of my games run in PAL, so I'm not sure it is a major issue. I could start putting the PAL option in WHDLoad for them.
It's just that I just noticed this...

I am assuming this is normal and some VGA displays just don't like the refresh rate???

Or do you think this should work and there might be something up with my GBS?

I did check the menu, and didn't see any setting I could change that would make a difference, I don't think.

Not critical, just something I noticed recently.

[amigappc]

Only thing I can say about GBS is, if you havent, modify it with gbs-control.

https://github.com/ramapcsx2/gbs-control

[desiv]

Originally Posted by amigappc

Only thing I can say about GBS is, if you havent, modify it with gbs-control.

That looks nice, but to be honest, if it is only going to work with PAL modes on my VGA monitors, I'm not sure how much effort I'd want to put into improving it, rather than looking for another solution all together.
I mean, it's great for what it is, but for the effort, a Pi2HDMI solution might be worth considering...