Atom Colour Board Thread

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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trixster
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Re: Atom Colour Board Thread

Post by trixster » Thu Mar 15, 2018 12:13 pm

https://shmups.system11.org/viewtopic.php?t=52172

I gave this a quick whirl last year; the pi seemed to work ok and i could access the menu options from the pi's composite out, but the gbs did not seem to like having input through the RGBHV. I didn't have time to try it further.
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Re: Atom Colour Board Thread

Post by trixster » Fri Nov 09, 2018 2:46 pm

I’ve got one of Prime’s Colour Boards Mk5.10c in my Atom and I’m attempting to connect it to my GBS8200. Sadly I’m not getting a picture. I’m using a DIN to 15HD (VGA) cable which works great for connecting either a beeb or Master to the 8200.

The cable is wired for standard Beeb on the DIN side:
1(R)
2(G)
3(B)
4(Sync)
5(GND)

and on the VGA side it’s:
1, 2 and 3 for R, G and B,
6, 7 and 8 are ground
13 is Sync.

The R, G, B, and sync all have 200 ohm resistors in the line, wired at the 15HD end.

I suspect the resistors are the problem. Can anyone advise what the problem might be?

Thanks!
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Re: Atom Colour Board Thread

Post by hoglet » Fri Nov 09, 2018 4:00 pm

trixster wrote:
Fri Nov 09, 2018 2:46 pm
I suspect the resistors are the problem. Can anyone advise what the problem might be?
You've tried cycling through all the different video modes I guess?

The only thing I recall is that too high a SYNC level causes the GBS-8200 to stop recognising the video signal. So it might be worth trying a larger resistor in line with the sync signal. Looking at the schematic I posted in this post, I ended up with a 430R resistor inline with sync:
viewtopic.php?f=44&t=5994&p=56123#p56123

Dave

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Re: Atom Colour Board Thread

Post by trixster » Fri Nov 09, 2018 4:24 pm

Yeah, I’ve tried cycling through the 4 different resolutions and have tried altering the geometry variable (clamp, size, posn etc). I’ll have a look at the cable to see about swapping out the sync line’s resistor.
Last edited by trixster on Fri Nov 09, 2018 4:29 pm, edited 1 time in total.
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Re: Atom Colour Board Thread

Post by danielj » Fri Nov 09, 2018 4:26 pm

Isn't prime's board at proper vga levels? Not ttl? You'd want no resistors in that case!

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Re: Atom Colour Board Thread

Post by hoglet » Fri Nov 09, 2018 5:17 pm

trixster wrote:
Fri Nov 09, 2018 4:24 pm
Yeah, I’ve tried cycling through the 4 different resolutions and have tried altering the geometry variable (clamp, size, posn etc).
Just to be clear, I wasn't talking about the different resolutions.

I was checking you had cycled through the different input sources (YPRPB, RGBS, RGBHV) - it needs to be set to RGBS.

Anyway, I've just dug out my GBS 8200 and connected it to Phill's Mk 3.5LS colour board and it works fine with or without resistors in the sync signal.

So I'm not sure what to suggest.

Does your GBS 8200 work with a Beeb?

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Re: Atom Colour Board Thread

Post by trixster » Fri Nov 09, 2018 5:36 pm

Yes, I’ve tried cycling through RGBS, RGBHV and YPRPB.

The GBS8200 works perfectly with my Beeb and Master with the cable I’m using.
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Re: Atom Colour Board Thread

Post by hoglet » Fri Nov 09, 2018 5:39 pm

Do you have another monitor or a SCART TV/Cable you could test the Atom Colour board with?

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Re: Atom Colour Board Thread

Post by trixster » Fri Nov 09, 2018 5:50 pm

A standard Beeb scart cable from RetroComputerShack on eBay is on the way, should be here tomorrow!

I did try it with a dell 2001fp which accepts 15khz signals but it stated mode unsupported which I suspect is because it’s expecting RGBHV over vga and not what a beeb/Master/atom outputs?

The dell supports composite in - is it possible to get composite from the atom / colour board?
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Re: Atom Colour Board Thread

Post by trixster » Sat Nov 10, 2018 11:21 am

Scart cable arrived, Atom works a treat!
5C0C70B5-B08F-4F03-B166-764C1BFCAF7A.jpeg
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Re: Atom Colour Board Thread

Post by hoglet » Sat Nov 10, 2018 11:48 am

trixster wrote:
Sat Nov 10, 2018 11:21 am
Scart cable arrived, Atom works a treat!
To be honest, that will probably look better than the GBS 8200.

Dave

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Re: Atom Colour Board Thread

Post by trixster » Sat Nov 10, 2018 11:51 am

Indeed, but the tv with scart (and the ossc) is in the lounge, and all the computers (and gbs8200) are up in the loft with monitors that have no scart inputs. Sadly as handsome as the Atom is it’s not going to get wife-approval to live downstairs :( so I need to find an acceptable solution where the Atom can live upstairs.

I’m assuming your RGB2HDMI will not work with the colour card?
Last edited by trixster on Sat Nov 10, 2018 11:57 am, edited 1 time in total.
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Re: Atom Colour Board Thread

Post by hoglet » Sat Nov 10, 2018 12:11 pm

trixster wrote:
Sat Nov 10, 2018 11:51 am
Indeed, but the tv with scart (and the ossc) is in the lounge, and all the computers (and gbs8200) are up in the loft with monitors that have no scart inputs. Sadly as handsome as the Atom is it’s not going to get wife-approval to live downstairs :( so I need to find an acceptable solution where the Atom can live upstairs.
Why not look for a cheap old LCD TV, like the Sony Bravia KDL 15G2000?

There are pretty common on eBay:
https://www.ebay.co.uk/sch/i.html?_from ... acat=11071
trixster wrote:
Sat Nov 10, 2018 11:51 am
I’m assuming your RGB2HDMI will not work with the colour card?
No, it would likely look dreadful, if you got a picture at all.

It might be possible to add a Atom mode to the software. But there is a hardware issue as well: the Atom actually supports two levels of green, so it's not simply digital/TTL level RGB like Beeb is.

Dave

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Re: Atom Colour Board Thread

Post by John Ferguson » Sat Nov 10, 2018 4:56 pm

For my Atom I bought a second hand TV and I found it had manual tuning to receive the output from the modulator. My colour board also displays on this.

John

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Re: Atom Colour Board Thread

Post by trixster » Sat Nov 10, 2018 6:05 pm

I removed the 200ohm resistor from the HD15 cable on the sync line but still don’t get a picture. I’ve also tried altering the r g and b resistor pots on the gbs8200 behind the vga input but again I get nothing. The master and Beeb still happily return a picture on the gbs. Not sure what next to try! :(
Last edited by trixster on Sat Nov 10, 2018 11:39 pm, edited 1 time in total.
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Re: Atom Colour Board Thread

Post by trixster » Wed Nov 14, 2018 12:01 pm

Right, I have an rgb to HD15 cable now with no resistors on the r g b and sync lines... reckon this is safe to test with the colour board and gbs8200?

I’m just a little paranoid that something might get fried on either the Atom, the colour board or the 8200! Or am I being silly?
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Re: Atom Colour Board Thread

Post by 1024MAK » Wed Nov 14, 2018 12:47 pm

The variable adjustments (preset resistors) for the colours on the GBS8200 board are in series with the red, green and blue input signals anyway. So turn them to midway.

Mark
Last edited by 1024MAK on Wed Nov 14, 2018 12:48 pm, edited 1 time in total.

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Re: Atom Colour Board Thread

Post by trixster » Wed Nov 14, 2018 1:20 pm

Okeydokey, I’ll give that a try [-o<

[edit] alas, still no picture. But crucially no dead atom =D>
Last edited by trixster on Wed Nov 14, 2018 1:26 pm, edited 1 time in total.
A3020 | A3000 | A420/1 | BBC B + 128K RAM/ROM + 20K Shadow + Pi0 + VideoNuLA
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Atari Falcon 060 | Saturn | PS1 | SNES | CPC6128 | C64 | 3DO | MD | Jaguar

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