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greggj

I need a new GTIA

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Hi y'all, my GTIA is playing up in a strange way (see screenshot). 

I need a new one. 

 

The current one in the computer is CO14889-O1

 

D352C6D6-BD19-475C-A48B-5E09CD06F7DE.jpg

IMG_5757.jpeg

Screenshot 2019-07-25 at 09.42.39.png

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Brad @ Best Electronics has some. Try emailing him with "Atari" in the subject line.

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20 hours ago, greggj said:

Hi y'all, my GTIA is playing up in a strange way (see screenshot). 

I need a new one. 

 

The current one in the computer is CO14889-O1

 

 

I think I bought a couple from B&C Electronics on ebay (user:myatari).

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I have a spare 5200 mother that was dead, there was damaged around the power switch, I pulled a pokey from it and it worked fine, but I'd sell the board for 5 plus shipping

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2 hours ago, masschamber said:

I have a spare 5200 mother that was dead, there was damaged around the power switch, I pulled a pokey from it and it worked fine, but I'd sell the board for 5 plus shipping

Sure, I live in the UK tho. 

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I have a 14805 (NTSC) GTIA laying around that I'd be happy to ship to the UK (from the US). Don't know what that would do in your board tho...looks like you probably need the PAL GTIA instead.

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4 minutes ago, greggj said:

Interesting stuff @Nezgar. I almost wish I could just borrow it and test it out 🙂

 

I tagged tf_hh in my previous post, so he may chime in. You could also PM him to ask directly. If there's doubt, I'm sure he'd be open to testing it for you if you sent him the chip. I presume you are in Europe? He is in Germany.

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21 minutes ago, Nezgar said:

I tagged tf_hh in my previous post, so he may chime in. You could also PM him to ask directly. If there's doubt, I'm sure he'd be open to testing it for you if you sent him the chip. I presume you are in Europe? He is in Germany.

 

I´m here 😀

 

When I look to the pictures sent by greggj, them I´m pretty sure that the GTIA fixer won´t be the cure here. The grey patterns are absolute okay. And the manufacturing datecode of the GTIA is also none of the involved ones known as "China bad PAL GTIA".

 

Further, my gut feeling would say that the ANTIC is the culprit, not GTIA. The GTIA only makes the TV signal & frames, which are okay, otherwise the screen would rolling endless or nothing really would be visible - but the screen itself (technically) is stable. The colour generation is fine. When I look at the first both pictures I would say, the MSC (Memory Scan Counter) of the ANTIC is bad. This pointer can hold at maximum 12 bits or 4 KByte address range and it´s used in the display list of ANTIC´s "program code". Maybe the highest of these 12 bits is defective, this would explain the mirror effects in the first picture or the "black hole"  in the 2nd picture.

 

So my tipp: Change ANTIC first.

 

Good luck, Jurgen

 

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Thanks guys, I replaced GTIA - it did not help with my issues. 

So just as suggested by others here - I need a new ANTIC chip :(

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