Atari STE to VGA via the GBS 8220 board

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wietze
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Atari STE to VGA via the GBS 8220 board

Postby wietze » Wed Jan 15, 2014 8:06 pm

Hi there guys,

after some looking around how to get the Atari STE connected to an LCD monitor, I found the GBS 8220 board via youtube:

http://www.youtube.com/watch?v=Kjseux-qJeQ (I believe its a Dutch guy, judging the accent).

I ordered the converter board, soldered the stuff together, such that HS + VS = S as mentioned in the video. When hooking up the STE to the Board, and the board to the LCD I get actual display.

However, on the youtube video, the display is very stable. In my particular case; I get a screen that shifts vertically, perhaps by a pixel or so. I tried to capture this on video:

http://frummel.org/~weedz/atari/gbs8220.mp4

I wonder if anyone has a suggestion what may be the cause of this. It should be possible (I hope) to get a steady screen...

Suggestions welcome!
Regards,
Wietze

wietze
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Re: Atari STE to VGA via the GBS 8220 board

Postby wietze » Wed Jan 15, 2014 10:23 pm

Ive done some testing and notice the following:
- When there is no disk-access, and no UltraSatan attached, while at desktop; the screen is steady
- When there is diskaccess, the screen is wobbly on the v-offset when the diskdrive makes noise
- When the ultrasatan is attached, the screen flickers constantly.

This implies that it is perhaps my PSU that needs fixing? Im not sure how much the Utrasatan connection requires, but it seems to influence it a lot.

Does this make sense?

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Re: Atari STE to VGA via the GBS 8220 board

Postby paul92706 » Wed Jan 15, 2014 11:46 pm

hi there, i was thinking of doing this mod, i'm tiered of viewing the hi/res black and white colors on my my monitor. Hmmm seems like a few bug issues there eh wietze?
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Re: Atari STE to VGA via the GBS 8220 board

Postby Guest » Wed Jan 15, 2014 11:53 pm

you have some psu issue with your ste or some earth loop
i tried and tried with this board
it just does not like atari
but works with others
its something to do with the pos going sync and frame speed
the board just does not perform
if you read this dont buy one


usually the bridge rectifier leeks over its diodes in the ste little round 4 pins 1amp
replace with a 3 amp one


also check the capacitors and replace as needed

check all of them
i use a meter and test each one
if its more than 5 - 10% off i replace them

a meter cost $5 from ebay http://www.ebay.co.uk/sch/i.html?_sacat ... er&_sop=15


the mod you mention is for st not ste

the ste provides a different sync timings and needs a different mods

the problem is there is so many firmware and boards to the GB things
and no way to flash your own blocks into it
it makes it hard to make a real worker

not seen it done for the ste
i put mine in the bin
and use a VBOX and svideo to vga works with all freq etc

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Re: Atari STE to VGA via the GBS 8220 board

Postby wietze » Thu Jan 16, 2014 12:01 am

Hello, thanks for your responses.

The board itself works very well. If I dont use the floppy drive and dont have the ultrasatan connected it gives a crispy clear display; if I run a demo (Blue Period of Paradox for example), and the disk is done loading, the display works like a charm.

I will test tomorrow with a PC PSU to see if its the PSU or not.

Regards,
Wietze

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Re: Atari STE to VGA via the GBS 8220 board

Postby Guest » Thu Jan 16, 2014 12:19 am

i think its something to do with psu
perhaps you need to tie everything to a common external psu
to localise any issues

and run a ground to the negative of all wall warts

in the usd their is a small bridge recifier

but if you run a ground from the psu side {outer of the plug}
and connect it to the chassis of the atari


this floppy seek sounds like the atari 12v rail isnt so good
the floppy is the only thing other than the sound 9v regulator
to use the 12v rail

what exactly happens when it goes wrong
does it loose sync??? or go blank
??

do you get any black lines on the picture
on RF out using a TV

often the best way to check an atari is to use RF out and also your converter

so you can see whats upsetting the GBS board

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Re: Atari STE to VGA via the GBS 8220 board

Postby Guest » Thu Jan 16, 2014 12:42 am

many people i see
leave boards like this with no ground plane
ie not in a metal box and ground all round screwed down with
all sockets carefully cut and screwed grounding

and then expect it to not have psu jitter etc !!!!!!

:megaphone: put it in a metal box
and ground the metal box to the ataris metal case

its an rf device so follow the rules

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Re: Atari STE to VGA via the GBS 8220 board

Postby Guest » Thu Jan 16, 2014 2:08 am

looking at the mp4 this is frame drip
its caused by a bad psu mains cable or the timing of interlaced to non interlaced vga {sync}
im glad to see you try to eliminate it with the ste psu
looking at the pic its very good
steady between states
so an interlaced vga needs 4 frames of non interlaced put in the right order by the frame store usually a few KB
if you have 'frame drop' its because the sync is one frame or frame set infront
and you need to delay it and invert it
and invert it again
using a 74LS will add 200us delay so.. work from that to get to the timing the gbs needs
the frame goes drip drip drip so the vga buffer isnt supplied with frames not fast enough but at the right time to be stored in the correct order
ive had the very same problem and this is why it went in the bin
so sync is lost every say 4 'sets' of reframes
so need to get a feel for the timing and adjust the gbs for its lag lead
or latency
in frame you should have
frame set sync vga = (sync + - sync) in terms of non interlaced 4 frames a set
try not too set your vga to wide screen use 4/9 to get a steady state
i threw mine away and dont have an ste now past a test one with added this and that
so ..... says it all
the TT works well for all ste crap
i think with vga lcd the scallers will just scale
perhaps if some people just doubled the hsync and vsync you would get more than you used too
before on vga monitors if you double both you get 4 pics
all the same size as a square
im not sure you can get the same
perhaps as ive said before some sat boxes will take rgb via scart and give3 out hdmi
this works
i also have a projector takes svideo or vga from the vbox and works VERY well
with st and ste
this board is flawed and its firmware unadjustable
there techs are crap
not because of anything other than no support or firmware flash or details :roll:
i had v 5.2 what ever that means

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Re: Atari STE to VGA via the GBS 8220 board

Postby paul92706 » Thu Jan 16, 2014 3:35 am

Were can the VBox be purchased at? i have an Ste so i asume as simbo says won't function correctly with GBS board.
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Re: Atari STE to VGA via the GBS 8220 board

Postby FedePede04 » Thu Jan 16, 2014 2:11 pm

it sound a little like the problem that i am having.
the first hour mine is steady but after an hour mine start to shift one / two pixel left and right. i have bought new caps for the psu,
but i have not change them yet. but i got my psu check out by one of my friend and it should be ok,
so i think in my case, that it is one of the caps, on the main board..

btw mine is a ste520 with 4mb
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Re: Atari STE to VGA via the GBS 8220 board

Postby wietze » Thu Jan 16, 2014 5:11 pm

FedePede04 wrote:it sound a little like the problem that i am having.
the first hour mine is steady but after an hour mine start to shift one / two pixel left and right. i have bought new caps for the psu,
but i have not change them yet. but i got my psu check out by one of my friend and it should be ok,
so i think in my case, that it is one of the caps, on the main board..

btw mine is a ste520 with 4mb


I am using a ste520 with 4mb as well.

I replaced the PSU today, but the same problem remains. If the system is bare and idle, no vertical-offset occurs. When the diskdrive is accessed, the vertical offset occurs. This happens with 2 different ST PSU's I used and also with a PC PSU. I also tried to put the diskdrive to a seperate power source but still the problem remains.

As far as I can determine, this rules out the diskdrive as the cause of the problem. Perhaps its capacitors on the Atari board itself; any specific capacitors that I can check?

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Re: Atari STE to VGA via the GBS 8220 board

Postby wietze » Sat Jan 18, 2014 3:49 am

I got the display stable. In the end I think it was a flaky sync signal combined with poor grounding.

This means (for me at least) that the GBS 8220 board is a nice way to convert the Atari STe output to VGA so that I can use a modern LCD display.

If anyone wants pictures or whatnot, I'd gladly post them.

Regards,
Wietze

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Re: Atari STE to VGA via the GBS 8220 board

Postby paul92706 » Sun Jan 19, 2014 3:39 am

wietze wrote:I got the display stable. In the end I think it was a flaky sync signal combined with poor grounding.

This means (for me at least) that the GBS 8220 board is a nice way to convert the Atari STe output to VGA so that I can use a modern LCD display.

If anyone wants pictures or whatnot, I'd gladly post them.

Regards,
Wietze

nice to know that this mod worked :) im looking to try it soon thanks wietze!
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Re: Atari STE to VGA via the GBS 8220 board

Postby dhedberg » Sun Jan 19, 2014 8:27 am

wietze wrote:I got the display stable. In the end I think it was a flaky sync signal combined with poor grounding.

This means (for me at least) that the GBS 8220 board is a nice way to convert the Atari STe output to VGA so that I can use a modern LCD display.

So what'd you do to make it stable?
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Re: Atari STE to VGA via the GBS 8220 board

Postby wietze » Thu Jan 30, 2014 5:45 pm

dhedberg wrote:
wietze wrote:I got the display stable. In the end I think it was a flaky sync signal combined with poor grounding.

This means (for me at least) that the GBS 8220 board is a nice way to convert the Atari STe output to VGA so that I can use a modern LCD display.

So what'd you do to make it stable?


- I resoldered the wires from the 13pin DIN to the GBS board.

This turned out to make the setup pretty much stable (most of the time). I noticed that after posting, at random intervals I still get a little vertical-distortion. After a longer amount of uptime, the distortion appears sometimes (I noticed after 2 days). If I then turn off the Atari and turn it on again, its gone most of the time.

I think it may be something on the Atari board itself that is not stable all the time. I have not yet takent he time (and I lack the expertise personally) to look into it further. The current solution is very workable for me, and Im fairly certain its at the Atari end of the setup, not the board.

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Re: Atari STE to VGA via the GBS 8220 board

Postby sniperstorm » Sat Feb 08, 2014 2:02 am

So is this the best solution we have? I am going to do it if so. I have run out of working color monitors.
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Re: Atari STE to VGA via the GBS 8220 board

Postby Silly_Pony » Sat Feb 08, 2014 10:49 am

wietze wrote: soldered the stuff together, such that HS + VS = S as mentioned in the video.


Don't do this, there is a real circuit you need to safely mix sync. Building it solved the problem for me (but I gave up on GBS board, too ugly).

Search the other GBS board threads. I think it was LM1881 based
1040STe, 1040STf

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Re: Atari STE to VGA via the GBS 8220 board

Postby sniperstorm » Fri Feb 14, 2014 3:26 pm

So is this solution good to go? Are all the bugs worked out? I am going to get the board if its working perfectly.
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Re: Atari STE to VGA via the GBS 8220 board

Postby Hippy Dave » Fri Feb 14, 2014 6:29 pm

So is this solution good to go?

No
Are all the bugs worked out?

Won't Fix.
I am going to get the board if its working perfectly.

The GBS 8220 board is a lemon. It will give you, and others that you talk to, grief and frustration.
The misinformation about this faulty board obscures possible solutions. Simply stay away.

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Re: Atari STE to VGA via the GBS 8220 board

Postby paul92706 » Fri Feb 14, 2014 10:00 pm

Hippy Dave wrote:
So is this solution good to go?

No
Are all the bugs worked out?

Won't Fix.
I am going to get the board if its working perfectly.

The GBS 8220 board is a lemon. It will give you, and others that you talk to, grief and frustration.
The misinformation about this faulty board obscures possible solutions. Simply stay away.

Thanks for the heads up hippy dave, i was close to getting one, not after the issues it has with the St.
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Re: Atari STE to VGA via the GBS 8220 board

Postby sniperstorm » Fri Feb 14, 2014 11:52 pm

What is the best solution? I need a good color monitor.
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Re: Atari STE to VGA via the GBS 8220 board

Postby Silly_Pony » Sat Feb 15, 2014 12:02 am

atari sc1224, phillips cm8833, Commodore 1084 etc.

No point wasting your time. Just spend the £££ up front rather than keep throwing money at these junk boards
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Re: Atari STE to VGA via the GBS 8220 board

Postby spiny » Sat Feb 15, 2014 11:24 am

sniperstorm wrote:What is the best solution? I need a good color monitor.



I did this mod:

viewtopic.php?t=15728

and I now use a cheap second hand flatscreen TV, and the picture is perfect, equally as good as when I use my CM 8833.


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