Re: Troubleshooting X/Lisa RAM boards - first draft

• On Sat, 3/26/11, James MacPhail <gg__at_email.domain.hidden> wrote:
  >
  > This would indicate Ian's board #3 needs a new chip at E6.
  >
  

Ding ding ding! And the winner is... James MacPhail!

I removed E6 from that memory board, and plugged it into my DRAM tester. Sure enough, it ran part way through the chip and hit an error at 8100h, telling me the chip was defective.

I fitted a socket, and a known good 4164, and plugged it into the Lisa - she fires right up, passes the memory test and boots into Lisa Office System.

So, now I've got a good spare RAM board! Excellent work for figuring this stuff out, James. If you're ever in the Albany area, I owe you a beer :)

I didn't have any particular problem desoldering the RAM chip, except for the power and ground pins - this is a four layer board, and I think the inner two planes are just ground and power. Although I'm used to fighting with power/ground pins, being that I use a 25 watt iron, these were a lot worse than normal. The rest of the pins didn't pose any problem though.

Now, all I have to do is tackle those other two boards. I'm not sure what to make of those yet, and while I have both a logic probe and a 'scope, it's not easy to get at the memory board while it's in the Lisa, so I'll have to come up with something.

-Ian

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