Stargate repair log

From: David Shoemaker <davids_at_oz.net>
Date: Sat Apr 13 2013 - 21:21:53 EDT

Board would come up with intermittent ram errors.

 

Going into self-test would almost always report a RAM 21 error.

 

Swapped Ram 11 and 21. Problem stayed at 21, so false error

 

Scoping the ram address and data lines looked good, everything running ok
and levels seem good.

 

Swapped the decoders 4 and 6 with known good, no change.

 

Looking at the schematic ram bank 2 goes through a 74ls374 at 3H,
piggybacking a new chip on top of it let self-test pass and ram test run for
5 minutes.

 

 

Replaced buffer chip at 3H

 

Self-test and ram test pass

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Received on Sat Apr 13 21:22:29 2013

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