[SunRescue] Ultra 1/170 motherboards.

[James Lockwood]

On Fri, 3 Sep 1999, David Murphy wrote:

> I've recently rescued a trio of Ultra 1/170 motherboards, just the
> bare motherboard with CPU but without memory or cases. I'm wondering
> what my options are in terms of turning these into runnable systems -
> I guess the ideal would be to acquire some dead Ultra 1 systems with
> failed CPUs or motherboards, or is selling the boards and purchasing a
> complete machine likely to make more sense?

The ideal would be to acquite Ultra 1 chassis, of course.  Unfortunately,
these don't turn up often as the power supplies seem more likely to die
than the boards.

Selling the boards might earn you a decent amount, but as it is hard to
hack together a power supply for them, they wouldn't bring in as much as
you might hope.  Those of you out there who are thinking "all I need to do
is solder a new connector on my PC powersupply" need to think again: the
U1 p/s generates CPU core voltages directly, but the regulating feedback
circuitry is on the motherboard.  In other words, there are +3.0V and
+3.3V in addition to the ubiquitous +5/+12/-12 lines, and they are
regulated by the motherboard itself through 2 pairs of sense circuits (and
have a swing of up to a volt).  Hardwiring fixed voltages to these pins
would pose a serious danger to the CPU.

That said, if you're going to get rid of them, mention it here.  Some of
us may have U1 powersupplies floating around in their garages underneath
the stacks of Kaypro and PDP-11 parts.  :)

-James