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EZRAM II


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Hi All,

 

I have an Atari ST from my childhood that in the last few months I've been working on restoring back to health. It was in storage but apparently with rain, it didn't fair to well. In any case, I got it all cleaned up and working, had to replace a couple chips, etc. However, in part of taking everything out, i removed the EZRAM II memory upgrade. I've been able to put it back in successfully (or at least to the point where the computer doesn't act weird), but I have no idea how to tell if it's working. The Diagnostic cartridge still shows 512k (or there-abouts anyway), and not sure if this should show up in that anyway. I know I have the part that goes under the video shifter as well as the one that goes onto the other chip (mmu I think) in correctly, however there is also a loose green wire coming from it. Does anyone know if that was supposed to connect to something?

 

If anyone has any instructions or a picture or something showing how it connects, that would be great. Unfortunately there isn't really much out there when scouring the web other than one original ad and a couple random posts.

 

Thanks!

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That's an earth/ ground wire I suspect. Usually it is screwed to the RF shielding (or soldered.. better, but can make dismantling a bit tricky depending on where it is soldered).


If you're getting 512k it probably isn't working at the moment, unless the on board ram has been disabled and the board is only partially working.. which seems unlikely.

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Great, thanks so much! Odd it doesn't address that weird (possibly ground) wire, but no matter, i'll go through this and make sure everything looks connected properly.

 

Okay, that green wire isn't ground, it goes to pin 18 on the video chip and the other end is just hanging there. Since the docs don't mention it, i'm guessing it came lose from a part of the board but no idea where it goes back. In fact, moving it around, the pin 18 side came lose so i had to solder that back on. I'll keep looking but its not looking good unless i can see a picture of another ezram ii that might give a hint as to what isn't working.

 

edit: okay, the 2nd pin on the bottom right of j2 here looks like it has some wires coming from it.. maybe that's where it came from...

 

let see if I can manage not to blow something up. :)

post-63863-0-99368400-1526275578_thumb.jpg

Edited by ngtwolf
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Great, thanks so much... Crazy how every version I find appears to be different, but most of those didn't have a picture I could use. Looks like they were building these things by hand and just changing the specs on the fly. Mine seems to have 3 wires vs the 4 on yours, with two 'real' type like your four, and that one green one which appears to have been a total afterthought. (although, technically these are all afterthoughts or they would have just used a larger ribbon cable)

 

I'll look at this on the weekend, I had to put my ST away while I worked on a different project. I've been trying to keep my mess down to a minimum lately after it got super unmanageable for a while there. :)

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  • 3 years later...
On 5/15/2018 at 2:33 PM, hwrd said:

Hope this helps

So, I know it's been quite a while.  It turns out that green cable must have just been a patch but where it connected wasn't needed (the connectivity between the correct wires seemed fine), so i'm back to the drawing board.

 

What is basically happening is it hooks up fine but just doesn't recognize the ram.  Not even bothering to give errors.

 

The one thing I did notice at one point was one of the pins on the DIP socket was missing, I replaced it but then I thought.. maybe it was supposed to be missing?  No idea.  Any chance if you still have this to get picture of the pin side of both the DIP socket as well as the PLCC pin side on the ezram ii?  Really wish i understood how this thing worked so I knew what to trace out.  

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14 minutes ago, ngtwolf said:

Any chance if you still have this to get picture of the pin side of both the DIP socket as well as the PLCC pin side on the ezram ii?  Really wish i understood how this thing worked so I knew what to trace out.  

I got the board downstairs, so I will take some photos on both sides of the three boards pieces.  Should I pluck the red tape off the long RAM board? It's been attached for 34 years...  ??

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