deskpotato Posted March 14, 2012 Share Posted March 14, 2012 Hi, I have an XE that was working perfectly and then has failed and is now giving the Red, or more like reddy-brown screen of death. Anyone know if this is a capacitor issue, graphics, an issue with the inbuilt missile attack game rom or hopefully any easy fix? Any help would be much appreciated.. Cheers. Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 14, 2012 Share Posted March 14, 2012 (edited) That issue isn't graphics related. Likely something has died such as CPU, RAM or something in the memory select logic. What power supply is it using? If it's the known bad type then it might be the cause. If you've got some cartridges, try them out. Ideal ones are the "diagnostic mode" games such as Asteroids & Star Raiders. The fix - not necessarily easy, on XE practically all chips are soldered in and desoldering is a delicate/risky process. It also makes diagnosis harder, on other machines you can just swap chips over to find good/bad parts. Without doing that, about the only thing you can do is use a logic analyser or oscilloscope. Edited March 14, 2012 by Rybags Quote Link to comment Share on other sites More sharing options...
sloopy Posted March 14, 2012 Share Posted March 14, 2012 Most common is RAM, RAM support, or IC select logic... In that order... If your experienced with a soldering iron (And as Rybags said the boards are delicate), you can start by replacing ram... sloopy. Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 14, 2012 Share Posted March 14, 2012 I've been intending to write a simple diagnostic cartridge program. The problem with the existing ones seems that they don't test for the basic signs of life. If the Ram is bad they can just not work at all. Without using any Ram, it should be possible to verify that graphics, sound, CPU have some functionality. A carefully worked set of DLists + character set in Rom and using PM collisions could be utilized to verify Ram select logic. Quote Link to comment Share on other sites More sharing options...
sloopy Posted March 14, 2012 Share Posted March 14, 2012 (edited) Rybags, that would be useful, a diagnostic mode cart would be good, making a OS ROM replacement 'tester OS' would be even better... Then as long as CPU/MMU/CS logic, are working, it would be able to test... as long as DRAMs or something isnt 'chattering'... we need SOMETHING to fill those 32in1's ;') sloopy. Edited March 14, 2012 by sloopy Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 14, 2012 Share Posted March 14, 2012 Replacement OS would have the problem that you need a "medium" functioning machine at minimum to be able to select it. Diag cart as I suggested has the advantage that the Ram, keyboard, video can be bad but it still has a chance to start up so long as the CPU works and the OS can supply those first few instructions to get it going. Quote Link to comment Share on other sites More sharing options...
deskpotato Posted March 14, 2012 Author Share Posted March 14, 2012 Well, looks like its terminal...at least for someone with my lack of electronic skills. Anyway, thanks very much to you both for taking the time to help, I appreciate it. Quote Link to comment Share on other sites More sharing options...
sloopy Posted March 14, 2012 Share Posted March 14, 2012 Even if you arnt able to fix, you may want to sell it for parts... Or trade for something else... sloopy. Quote Link to comment Share on other sites More sharing options...
SIO2 Posted March 23, 2014 Share Posted March 23, 2014 Most common is RAM, RAM support, or IC select logic... In that order... If your experienced with a soldering iron (And as Rybags said the boards are delicate), you can start by replacing ram... sloopy. I recently fixed an XE GS by replacing RAM. I don't know if this will help anyone but, I thought I would describe the symptoms and steps. On first testing the machine with a known good power supply, I noted that the green power LED came on. However the TV screen presented was solid yellowish. I opened the case and touched the top of the RAM chips (lower left corner of the motherboard). The top one was getting hot making me suspect it had failed. The bottom RAM IC was not getting hot so, I thought perhaps it was still good. The machine had OKI M41464-12 RAM chips installed. I removed the top one and replaced it with a Texas Instruments TMS-4464-12NL. I again tested the machine with a known good power supply. Again the green power LED came on and the TV screen presented as Black with the TV on. Neither RAM chip was getting hot now. Since the machine still did not work, I then removed the lower OKI RAM and replaced it with a TI RAM. This time the machine booted to Missile Command. I played a game of Missile Command. Then I tested a couple of carts and booted the machine with option down and ran the RAM test which was all pass. So, perhaps RAM is the best place to start regardless of the screen color you see from a broken machine. Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 23, 2014 Share Posted March 23, 2014 Screen colour isn't totally relevant - normally GTIA will start up with $F0 as the background colour which appears as reddish brown. If it starts brown then changes to black then that means at least the OS is getting part of the way up. Similarly, sometimes on startup there will be stripes which are PM graphics at some random position with usually solid graphics - if they appear then go away, then the OS is making some inroads. 1 Quote Link to comment Share on other sites More sharing options...
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