Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!zds-ux!zds-oem!easton
From: easton@zds-oem.UUCP (Jeff Easton)
Newsgroups: comp.sys.zenith
Subject: Re: 386SX / small power supplies
Message-ID: <3@zds-oem.UUCP>
Date: 23 Feb 90 17:44:51 GMT
References: <22275.25dc6dd8@kuhub.cc.ukans.edu>
Organization: Zenith Data Systems OEM Engineering
Lines: 46




In article <22275.25dc6dd8@kuhub.cc.ukans.edu>, arritt@kuhub.cc.ukans.edu writes:
> I'm in the market for a 386sx, and our state contract says "thou
> shalt buy Zenith and no other".  The Zenith 386sx has a 120 watt
> power supply, which seems unreasonably small.  The Zenith sales
> rep said they use some special chips which reduce the power

  Ack!  special chips?  I happen to have a Z386sx power supply here, the
ratings are as follows:

	+5v  14A
	+12v 4A
	-12V .5A

  Now lets look at the load of a typical computer.  First off, the main 
board, fully loaded with 8 megs of RAM, coprocessor, etc. proabably takes
around 4 amps of the 5V line with around 100 ma on the +-12v lines.  I'm
guessing on the high side here.  That leaves 10A @ 5V for the slots.  One
slot has a VGA card, less than an amp @ 5V.  That leaves you with slightly
more than 2 amps @ 5v per slot, plenty for most cards.  The drives take
small amounts of current @ 5v, maybe an amp for all three.  The drives
do require maybe 1.5 amps from the 12v line, more for startup.
  This just about fits the supply ratings above.

> Anyway, my questions to you fellow netters:  Does anyone have 
> experience with these units (or other Zeniths with very small
> power supplies)?  Is this a practical consideration?  What happens
> if I add a tape backup, a transputer board, maybe a few more
> megabytes of memory, or other electrical load?

  Well, I have a little experience with Zenith units ;^).  The 
transputer boards could draw quite a bit of current.  Most
other AT type boards will be okay.

> Ray Arritt                        | 



	Jeff Easton			Zenith Data Systems
	Systems Engineer		OEM Engineering
	easton@andrews.edu     --or--
	easton@zds-oem.zds.com
	 I'd rather be Water Skiing...