Video driver thoughts

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exxos
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Re: Video driver thoughts

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sandord wrote: Thu Nov 29, 2018 2:33 pm I think that this observation is interesting: the problem appears to happen only vertically, horizontally the colours are often wrong but consistent. Just as if the palette changes per line...
I could only really assume some of the colour bits are wired incorrectly on the RGB lines... I did doublecheck RGB lines on the schematics...

Also possible the Sample clock might be inverted to what it needs to be... For example maybe the colours are changing when the DAC latches the data..
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Re: Video driver thoughts

Post by sandord »

exxos wrote: Thu Nov 29, 2018 2:35 pm I could only really assume some of the colour bits are wired incorrectly on the RGB lines... I did doublecheck RGB lines on the schematics...
Surely then the colours would be wrong all over the place, horizontally and vertically.
exxos wrote: Thu Nov 29, 2018 2:35 pm Also possible the Sample clock might be inverted to what it needs to be... For example maybe the colours are changing when the DAC latches the data..
That makes a lot of sense. Perhaps you can reconstruct some signals instead to verify behaviour?
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Re: Video driver thoughts

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sandord wrote: Thu Nov 29, 2018 2:40 pm That makes a lot of sense. Perhaps you can reconstruct some signals instead to verify behaviour?
I think the clock needs inverting, not sure the easiest way to do this...
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Re: Video driver thoughts

Post by PhilC »

So, can I throw another spanner in the works?

I've been struggling to get the same output as you guys, although I have now succeeded.

I had been using CO7013-002 IMP shifter, switch it to CO25914-38A and I get a similar output. With the IMP I was just getting a really dark screen.
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Re: Video driver thoughts

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Forgottenmyname wrote: Thu Nov 29, 2018 2:48 pm So, can I throw another spanner in the works?
No, we good thanks. :lol:


I put the clock on the 16MHz output, no change..

Maybe the Analogue section does need to go via a 10R resistor like on the Falcon.. Really out of any other ideas..
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Re: Video driver thoughts

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exxos wrote: Thu Nov 29, 2018 3:00 pm Maybe the Analogue section does need to go via a 10R resistor like on the Falcon.. Really out of any other ideas..
Looking at your picture/video again: as the white turns purple, it seems that only the green signal is suffering. What happens if you disconnect it? Does the picture look stable then?
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Re: Video driver thoughts

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exxos wrote: Thu Nov 29, 2018 3:00 pm
Forgottenmyname wrote: Thu Nov 29, 2018 2:48 pm So, can I throw another spanner in the works?
No, we good thanks. :lol:

Spoil sport. am ready whenever you want something else tested. In the meantime I'll fix my floppy problem.
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Re: Video driver thoughts

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sandord wrote: Thu Nov 29, 2018 3:02 pm Looking at your picture/video again: as the white turns purple, it seems that only the green signal is suffering. What happens if you disconnect it? Does the picture look stable then?
This is with Green disconnected...

IMG_3611.JPG
IMG_3611.JPG (90.66 KiB) Viewed 3538 times


I will try RGB on their own see what happens...
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Re: Video driver thoughts

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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: Video driver thoughts

Post by Icky »

So it’s not just me. I feel vindicated. I thought I was the one that causes BAD Chips to be named or even NASTY ones.
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