[rescue] How to find the failed chip(s) on a VME 1102 board? (Answered!)

[Adam Kropelin]

Adam Kropelin wrote:
> Hi everybody... I powered up my 3/280 this morning for the first time
> in about a year and popped it into diag mode to make sure the
> hardware was as happy as it was the last time I ran it. Alas, it
> appears I have one or more failed chips on one of the 1102 memory
> boards: 
> 
> Can anyone point me to a reference on how to convert the failed
> address into a part designator so I can replace the right chip? I've
> made a guess but I don't really want to whip out the soldering iron
> unless I'm sure I'm spending my time on the right chip.

[This message is posted to two lists since I asked essentially the
same question both places. Adjust your replies accordingly and
my apologies to anyone who ends up getting this twice.]

Although several kind list members stepped forward to help me find
a replacement RAM board, I never did find anyone who knew how
to take the diag mode error message and deduce which chip was
faulty.

Well, that's all about to change... :)

I did a rather lot of experimenting and circuit board tracing and I've
managed to map the DRAM IC layout. I also deciphered the wiring
of the EDC engines so I now know how to take the reported syndrome
and determine exactly which chip to replace. I was able to swap out
a single chip on my board and get it back working again.

I've summarized the information I learned and posted it at the URL
below. The content is fairly technical at the moment, though I plan to
add a tool where you can plug in the magic numbers from your error
message and it'll tell you what chip to replace. This is forthcoming
the next time I get bored...

http://www.kroptech.com/sirius

Comments, questions, and criticism welcome...

--Adam