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Path: utzoo!watmath!watdcsu!rsellens
From: rsellens@watdcsu.UUCP (Rick Sellens - Mech. Eng.)
Newsgroups: net.micro.pc
Subject: Re: Adding a hard disk to your IBM PC
Message-ID: <926@watdcsu.UUCP>
Date: Fri, 8-Feb-85 14:58:54 EST
Article-I.D.: watdcsu.926
Posted: Fri Feb  8 14:58:54 1985
Date-Received: Sat, 9-Feb-85 05:46:31 EST
References: <420@rlgvax.UUCP>
Reply-To: rsellens@watdcsu.UUCP (Rick Sellens - Mech. Eng.)
Distribution: net
Organization: U of Waterloo, Ontario
Lines: 27
Summary: 


Re: running a hard disk with the 65 watt power supply

I added a 10 meg half height drive to my fully loaded, 64K mother board
PC last June. I had no problem until I had had the machine on for about
3 hours when the system just crapped out.

After a fair bit of messing around I found the following was the problem
	- When chips are hot they draw more current.
	- When the floppy drive starts up there is an initial high
	  current transient.
	- If that transient goes over the power supply limits the supply
	  will shut down.

The result is semi repeatable crashes when the machine is hot and the
floppy drive is accessed. The simple solution is more power. It can be 
either a replacement XT type power supply (big $), a "clip on" sold for
just this purpose (smaller $), or even the power supply from an external
floppy drive. I took the last course because a friend had an unused
floppy enclosure that he let me have for next to nothing. I've been 
running this way for about eight months with no problems.


Rick Sellens
UUCP:  watmath!watdcsu!rsellens
CSNET: rsellens%watdcsu@waterloo.csnet
ARPA:  rsellens%watdcsu%waterloo.csnet@csnet-relay.arpa