Qbus Backplanes

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sat Jun 7 17:24:00 2003

> It locks up during the diagnostics, most often during the memory tests.
> I've managed to get it to go though to the point where it was ready to
> boot a couple of times. It seems to get worse if I leave the system
> powered up. I know its not the boards, since I've tried known good sets.

As others have suggested, check the power lines _at the backplane or
boards_. This really does sound like a power problem, but it might be
something like a bad connection in the power harness which causes the
voltage at the backplane to be too low, while the PSU output (and the
voltage at the drives) is fine.

Also, if you have a 'scope (and if not, why not?), check for ripple on
the power lines.

Have you checked the power fail lines (ACLO and DCLO)? Strange things
happen when they get asserted at random...

-tony
Received on Sat Jun 07 2003 - 17:24:00 BST