[SunRescue] Ultra 1/170 motherboards.

[Keith Campbell]

-----Original Message-----
From: James Lockwood <lockwood at isi.edu>
To: rescue at sunhelp.org <rescue at sunhelp.org>
Date: Friday, September 03, 1999 02:01 PM
Subject: Re: [SunRescue] Ultra 1/170 motherboards.

>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.


Do you (or anyone else here) know enough electrical design and know what is
required to interface a PC powersupply with a U1 motherboard?  Care to draw
up a circuit?  Something like this could come in very handy :-)