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kirby76

Need some advice on repairing my 800XL

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I picked up this Atari 800XL from the market place and It's not booting into Basic, just straight into memory test showing the last row of 8 blocks red. I read that this row was reserved for Basic. Do you think replacing the Basic chip will fix this issue? Also can someone please tell me if the 2 wires in the second photo is a common thing on the 800XL. Maybe It's there because of bad traces? Regular cart games boot but the Atarimax MYIDE ][ does not. All chips are socketed. I tested the DVI Sophia board inside the GTIA chip slot and it was working really well with a sharp picture on a CRT. I would like to also install more memory but first I need to fix these red block errors. Any feedback would be greatly appreciated.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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It's the ram. Looks like the ram is socketed, so it will be a snap. Best Electronics. EASY. Just take care in putting the new ones in.

Edited by Paul Westphal
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I just got of the phone with them. He told me to swap the first row of the 4 ram chips with the other row and see if the error is still there. I tried that with no luck. So we put in an order for a set of 41256k ram chips. I hope this fixes the issue. Thank you

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To be quite honest, I'm as much concerned with the video display.... Is that top pic really what it looks like?

 

I mean, you said you had a sharp picture under other conditions, but what I'm seeing makes me wonder what else may be wrong?

Edited by Tillek

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Can you plug in the keyboard and hold down the option button and do a full memory test? The last 8 blocks not showing up where Basic "sits" in memory.

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To be quite honest, I'm as much concerned with the video display.... Is that top pic really what it looks like?

 

I mean, you said you had a sharp picture under other conditions, but what I'm seeing makes me wonder what else may be wrong?

The fuzzy picture was from RF. It got worst when I removed the heat shield.

Edited by kirby76

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Can you plug in the keyboard and hold down the option button and do a full memory test? The last 8 blocks not showing up where Basic "sits" in memory.

 

Thanks for responding. This is what i got from the full memory test. Last 2 rows all red.

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Yes, those two wires are common on a lot of them.

 

How about swapping around U26 and U27 for a test to

see if the pattern changes in the self test? Might

need to replace these if we can get it to change by

doing this. At this point it could still be CPU, MMU

and a host of others too, but hey what fun!

 

There must be a bug in the self test code as usually

three rows is all I've seen. And this could bad ROM

itself or the bug acting only with the particular

defect. At any rate BASIC occupies the last half of

the last row of three.

 

So your first screenshot if it were all green squares

is what we want to see if it was booted with BASIC ON.

Last screenshot is not possible, but there it is anyway.

I'm leaning towards a failing ROM chip U5 at the moment.

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How about swapping around U26 and U27 for a test to

see if the pattern changes in the self test? Might

need to replace these if we can get it to change by

doing this. At this point it could still be CPU, MMU

and a host of others too, but hey what fun!

 

I hear ya. I really can't wait to try the new chips to get this up and running. I just tried what you recommended by swapping the U26 / U27. Both tests are giving me the same results as previous :(

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https://www.ebay.com/itm/6-Atari-Video-A-V-TV-Cable-Composite-Video-Audio-800-800XL-65XE-130XE/232541246443?hash=item362489d3eb:g:Ey0AAOxytdlQ9xAv

 

Here is your video cable.

 

FYI - when you put in the ram chips ( not sure why he sold you 256k rams ), put one side kinda in there and slightly bend the other side to go in with your fingers, then pop it in. Notch on chip to the left, all chips same direction. Make sure all feet are in. New ram chips go in hard.

 

Eightbitfix.com

Edited by Paul Westphal
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256k RAM chips will work fine but it will only use 64k

you can always do a RAM upgrade mod at a later date! :)

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FYI - when you put in the ram chips ( not sure why he sold you 256k rams ), put one side kinda in there and slightly bend the other side to go in with your fingers, then pop it in. Notch on chip to the left, all chips same direction. Make sure all feet are in. New ram chips go in hard.

 

Eightbitfix.com

Thanks for the tip. Shoot, the chips that are already in there are tough to take out\put in so I can only imagine how tough the new ones will be. I ordered a few other things for this 800xl. I definitely ordered the Composite cable and some other chips like the Antic one just to be safe. I wanna hook this bad boy up to my Commodore monitors so bad. I've been sitting on a barebones 256k Wizztronic revF board for awhile. That's why we went with the 41256k ram chips. I hope everything gets shipped out today.

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This is the exact cable that I am using to hook my 800XL to a 720p LG HDTV. The resulting video signal looks *amazing* and seriously almost as good as Altirra does with a PC HDMI out to the same TV. Back in the day, I would have never thought that a stock XL could look so good.

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It works!! New chips arrived in a day from Best Electronics. The 800xl booted into Basic on the first shot and it is now running my Atarimax MYIDE ][. Tested using their gold plated composite cable on a 13'' Daewoo CRT. Later through the week I will feed it to all sorts of CRT screens especially with the Sophia DVI board. Now I need get this girl up to 256k. She's running pretty.

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Edited by kirby76
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