jschipmann Posted August 1, 2018 Share Posted August 1, 2018 While I still own my original childhood Atari 400.... when Iwas presented with the opportunity to purchase an Atari 800 at a yard sale for $20 I hopped right on it. I got it home, made an s-video cable for it and started testing it out.... only to find out something was odd I'll try to get some pics of it (or video of it in action) but in the mean time I can only describe the problem as the characters or sprites on screen are enlarged. For example on MS Pac-Man, Ms Pac-Man and the ghosts are irregularly large while the maze looks normal. In space invaders everythign looks off and the device you are shooting from to derstroy the aliens is half the screen.... I still have yet to take the system apart fully and check for damage, but I did quickly take the rom and ram carts out of the top and clean thier connections and slots. The same games play fine on the 400, so it is not the carts. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted August 1, 2018 Share Posted August 1, 2018 GTIA 3 Quote Link to comment Share on other sites More sharing options...
jschipmann Posted August 1, 2018 Author Share Posted August 1, 2018 (edited) I thought that was more for color or clocks? ahh I see different modes... so if I open it and see no signs of issues (corrosion, traces, components, solder joints etc) then only option is to source a replacement? Edited August 1, 2018 by jschipmann Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted August 1, 2018 Share Posted August 1, 2018 I thought that was more for color or clocks? ahh I see different modes... so if I open it and see no signs of issues (corrosion, traces, components, solder joints etc) then only option is to source a replacement? Agree that it sounds like a bad GTIA chip. Good news is those are pretty cheap from Best Electronics. He does have a $20 minimum on orders though. Might be worth buying a couple other items as well. 1 Quote Link to comment Share on other sites More sharing options...
R.Cade Posted August 1, 2018 Share Posted August 1, 2018 Send some pictures before you fix it. That sounds like an interesting defect. Does collision detection affect the large versions? Quote Link to comment Share on other sites More sharing options...
jschipmann Posted August 1, 2018 Author Share Posted August 1, 2018 Agree that it sounds like a bad GTIA chip. Good news is those are pretty cheap from Best Electronics. He does have a $20 minimum on orders though. Might be worth buying a couple other items as well. This page? http://www.best-electronics-ca.com/custom-i.htm any advice on common items that may go bad typically on atari 400 or 800 to fill the $20? Send some pictures before you fix it. That sounds like an interesting defect. Does collision detection affect the large versions? I'll play some and upload some video to youtube I love tinkering and working with stuff like this, but have a lot to learn! 1 Quote Link to comment Share on other sites More sharing options...
jschipmann Posted August 26, 2019 Author Share Posted August 26, 2019 Well... I can now see how busy my life is now that I'm visiting this over one year later lmao. Decided to take a week off of work for a staycation of sorts lol. I've got this hooked back up and have been messing around with it. I took it all apart and re-seated the chips on the CPU card (I'm not sure yet which was the antic and gtia etc...) but I took them out and re-seated either way. I didn't try any contact cleaner yet. However I just a couple weeks ago aquired an atari 800xl, and I happen to have a Atari 400... I assume the 400 would have the same card in it correct? should I try swapping the GTIA between the systems to verify? here is a pic of the one out of the 800: https://photos.app.goo.gl/Uaj1mHQsRiGay23S9 Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted August 26, 2019 Share Posted August 26, 2019 The chip numbered "C014805" is the GTIA. That's the one that seems to have the issue, based on your description of symptoms. 1 Quote Link to comment Share on other sites More sharing options...
jschipmann Posted August 26, 2019 Author Share Posted August 26, 2019 Hopefully the links work, here are some video examples. Ms Pac-Man https://photos.app.goo.gl/48RVsZZVpcfUMzFQ7 Donkey Kong https://photos.app.goo.gl/7jq8GUrAZ7fGf5nRA Hooked to my CRT TV Via S-video cable. So try to swap the GTIA from the 400 to the 800 to see if that works? and then if so get another... Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted August 27, 2019 Share Posted August 27, 2019 That's great. You have an original 6502 board, not a Sally board. You can plug a 65C802 chip in and get 816 compatible opcodes, but no high RAM. That's what I run. Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted August 27, 2019 Share Posted August 27, 2019 After watching your videos, I would suspect GTIA. Quote Link to comment Share on other sites More sharing options...
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