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Atari 800 xl brown screen

Desperado

Veteran Member
Joined
Nov 25, 2017
Messages
6,786
Hi guys i wanna wish merry Xmas to all!!
Im here cause i ve one Atari 800Xl...when i turn on i can see red led light but on Tv
i see only dark brown screen...I tried with antenna and composite cable but nothing changes...
Can someone help me to repair please?
Thanks!
20191224_130150.jpg
 
And a Merry Christmas to you too ilpaninaro.

Is the dark brown screen actually coming from the Atari 800XL or not? What do you get on the screen if you turn off the Atari in this mode?

The 800 XL has a self test mode (see section 2 of http://classiccomputers.info/down/Atari/Atari_800XL_Field_Service_Manual.pdf). Will it even go into self test mode at all?

Dave


Hi Daver2!!
I saw Atari service manual and i read that red or brown screen can be caused by UC 2-5, 18, 19, 28 or 30
 
If your 800XL has it's main chips socketed, you should try re-seating all of them. If you are using the original Atari power supply it would be wise to check it as well.
 
If your 800XL has it's main chips socketed, you should try re-seating all of them. If you are using the original Atari power supply it would be wise to check it as well.


I have original power supply and voltages are correct....i tested all ic ram and they works correctly...
 
In Atari s' manual i founded these logic reading in normal status:
Schermata 2019-12-26 alle 15.27.31.png
Schermata 2019-12-26 alle 15.27.56.png
 
I tested with my logic probe and i founded some troubles:

U2:
1:H
2:L
3:0
4:H
10:H
11:H
12:H
13:H
14:H
15:H
16:H

U3:
1:L
2:L
3:L
4:L
5:L
17:H
18:H

U4:
8:L

U5:
10:L
 
Please @daver2 can you help also here?? ;)

I ve bought another 800xl atari but when i turn on, he starts alaways with ram self test mode...i tryied to press "option" key but nothing change....
 
I tested all ram chips and are all ok...i changed the 2 roms from a good 800 xl but nothing change...
Please can you help me to test with scope or logic probe?? ;)
 
The information you require is in the document I linked to back in post #2.

Look in the document for the symptom "Red/Brown screen" and it specifies what devices to change in what order.

Dave
 
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