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Atari 5200 Zero RAM DRAM Test (Find Bad RAM ICs)

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Bad RAM chips are probably the most common 5200 failure. Here is a small program that will run on a console even if you take out all the RAM chips and show which chip or chips are not working.

 

This will only identify bad DRAM that are fully non-functional, though most DRAM do fail that way. Bad/missing DRAM will show a red bar, working ones a green bar.

 

The u# shown on the screen are for the 4-port 5200. I don't have a schematic of the 2-port model handy to see if they have different PCB markings.

 

The ROM attached is a standard 32K binary. You can use any type of reproduction board to make a cart. If you can't make a cart yourself Albert may still make them, or you can PM me and I will try to find time to make a few.

 

You can load this from the Ultimate SD menu, but the Ultimate SD already requires working RAM, so running it from there is not possible on a system with bad ram. For those cases I have attached a specially packed core_boot.rom that can be used to replace the Ultimate SD standard boot rom. This requires re-flashing your SD cart back to the standard boot rom after use. More information is in the "readme_first.txt" file in the archive about this procedure.

 

If this program fails to run on the non-working 5200 console then the problem is probably bigger than just a bad RAM IC and you can start looking more deeply for other issues.

 

Steve

post-934-0-02804400-1319174070_thumb.jpg

ZeroRAM.zip

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I don't have a schematic of the 2-port model handy to see if they have different PCB markings.

 

On 2-port model chips are marked Axx. RAM chips are from A18(D7) to A25(D0).

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I don't have a schematic of the 2-port model handy to see if they have different PCB markings.

 

on board 2-port models chips are marked Axx, RAM: A18(D7) to A25(D0).

Edited by eightbitter

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I was able to verify that this works on a dead board as well as a working board using the Ultimate SD cartridge. I just put core_boot.rom in the /Recovery folder to flash it, then removed the rom and left the /Recovery folder there. The RAM test came up fine. Reflashed by putting the standard core_boot.rom in the /Recovery folder to flash it, then removed the rom and left the /Recovery folder there like the last time. Even on my dead board the RAM's tested fine, so it must be a problem somewhere else. thanks!

 

Matt

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By the way, I'd really hate to sound like a noobie, but I pulled the cartridge PCB out of a 5200 Dreadnaught Factor and took the rom out. How hard is it to retrofit a standard 2732 eprom so that I can use it for diagnostic programs?

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You would need a 27256 eprom ( 32kbit x 8 ). I don't have any instructions for modifying ROM boards though. I know Albert used to sell a 5200 PCB that just needed the eprom soldered in and you were ready to go.

Edited by classics

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sorry to be a dumbbum but anybody know where to buy replacement ram chips for a 2 port unit i didnt use this test but i can feel the top rem chip is getting hot

 

then i switched the top for the bottom one and the bottom for the top and the top one now on the bottom is still getting hot

Edited by bohoki

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sorry to be a dumbbum but anybody know where to buy replacement ram chips for a 2 port unit i didnt use this test but i can feel the top rem chip is getting hot

 

then i switched the top for the bottom one and the bottom for the top and the top one now on the bottom is still getting hot

5200's used an odd RAM chip. Best Electronics still has them.

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