How to find the bad DRAM

[matsondawson]

I just spent the day de-soldering all the ram in a 800XL just to find one bad ram chip.
Is there an easy way of finding the bad IC?
You'd think they would have made the memory test in the Atari identify the bit that's not working.

[tezza]

Did you try the piggyback method in the Atari 800XL? This doesn't always work but in my experience it often does. I diagnosed a faulty Atari 800XL a while ago by using this method. It didn't work on my Apple IIe, but I'm sure there was more than one faulty chip on that one.

I've seen reference to equipment you can buy which which will allow testing of logic and RAM chips. I'll try and dig up the details.

BTW what blew the Atari DRAM in the first place? In my case it was a malfunctioning PSU.

[matsondawson]

I don't know what caused it, it was a hand me down.
I tried piggy backing but that just made the machine completely broken.
Interesting the broken RAM pattern you had was exactly the same as mine, mine was the third chip to the front, which was yours?

[tezza]

I don't know what caused it, it was a hand me down.
I tried piggy backing but that just made the machine completely broken.
Interesting the broken RAM pattern you had was exactly the same as mine, mine was the third chip to the front, which was yours?

As I indicated in the figure label, that faulty RAM pattern displayed in the article isn't mine Matt. I swiped it from another site as I didn't take a photograph of mine. The pattern could have been different. I can't even have a look easily as the machine is all closed up and stored.

[lilliann]

I think you have to search for bad ic on any computer hardware shop. you can find so many bad chips there with old rams or ask from any person who have old computer and who store old parts of computers.


__________________