graphics corruption on 1200

[golem]

Hi
I have a Commodore A1200 with Blizzard 1230 inside it. But I don't believe the accelerator is to blame for this problem. After it is on for a while I get minor screen artefacts (like a short line of pixels) that jump around a small screen area. It is still very usable but a bit annoying and I would like to get a rock solid display like my other A1200. The reliable one was bought new from Power computing and I am led to believe it had the timing fixes done. And it is also Escom. I am using straight AGA modes with native chipset. I admit I haven't yet isolated the RAM on the troublesome one but do you think this is more likely timing problem or flaky motherboard? And if so is there a specific timing fix that i need to perform?
Thanks if anyone can help me.

[pan1k]

I think this is the same problem I am experiancing. Mine only happens after I have had it off overnight (or a few hours). It goes away after about 20-30 minutes of use. My workbench wallpaper also flashes, certain color pixels that is. :crazy:

[Tomas]

I have heard that on some models of the a1200 some chips have a tendency of overheating. Placing a very small heatsink or similar ontop of this troublesome chip will solve this issue from what i have read. I sadly do not have any info about which chip and such, so i hope someone else have more knowledge on this area?

[orange]

I've heard it too.
Its Alice chip, and AFAIK it gets pretty hot on all Amigas that have it.

its mentioned in this old thread



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my 2^10 post.. juhu! :-)

[starf81]

Did you install patches like Fblit or similar?

[Piru]

@golem

Known hardware issue. It's nothing serious and it can be worked aroung with some cooling or by adjusting some components on the mobo (sorry, I can't find the instructions right now, either).

Quick software workaround is to adjust the white colour from 255,255,255 to 254,254,254. This cures it for desktop use, at least.

[golem]

orange wrote:
I've heard it too.
Its Alice chip, and AFAIK it gets pretty hot on all Amigas that have it.

its mentioned in this old thread



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my 2^10 post.. juhu! :-)

Happy 1024th post!
I never heard about this Alice problem. Did you manage to fix it with a heatsink like Tomas says then or have you just put up with it?

[golem]

Piru wrote:
Quick software workaround is to adjust the white colour from 255,255,255 to 254,254,254. This cures it for desktop use, at least.

and in previous thread linked by orange;

Piru wrote:
There are even patches in aminet that patch all 255,255,255 colours to 254,254,254 to workaround the problem.

Thanks guys - didn't know that. I'll download the patch. I though I'd installed Fblit and it didn't make a difference but either I was wrong or Fblit doesn't patch the 255 to 254.

[systmcrsh]

take a picture or screengrab and make yourself some "glitch art" like this guy:

http://www.beflix.com/store.php

[golem]

systmcrsh wrote:
take a picture or screengrab and make yourself some "glitch art" like this guy:

http://www.beflix.com/store.php

Yeah very post modern.  :-)

[orange]

@golem
it turned out to be some other timing problem, I used one of those A1200 motherboard fixes and its pretty stable now.