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From: beyo@beyonet.UUCP (Steve Urich)
Newsgroups: comp.sys.3b1
Subject: Re: fan speedup-power supply question
Summary: 3b1 PS vs pc-7300 PS
Message-ID: <171@beyonet.UUCP>
Date: 13 Jun 91 17:05:11 GMT
References: <1991Jun12.125517.9615@news.gvl.unisys.com>
Distribution: usa
Organization: Beyonet Network
Lines: 40

In article <1991Jun12.125517.9615@news.gvl.unisys.com> derekp@gvlf9-m.gvl.unisys.com () writes:

	[Fan stuff deleted]

>		2. The power supply: The one I bought was marked 
>			Power Systems: pn PS-1569
>			5v/20a 12v/3.5a -12v/100ma.

	<*> This is a PC-7300 195W PS. -12v should be 300ma.

>			Power Systems: pn PS-1610-1
>			5v/20a 12v/5a -12v/300ma.

	<*> This is a 3b1 2meg motherboard PS at 245w.

	From what I can see the difference between the 2 PS's are as follows:

		PC-7300	195w				UNIX-PC 245w.		
----------------------------------------|------------------------------------
Q1:         JE8503                      |     MJ12005 /w larger Heat Sink
R6:	1.5k @ 2W (2W guess)            |     1.5k @ 5W (5W guess)
C102,103:	470uF @ 50v (BOTH)      |     10000uF @ 6.3v (BOTH)
Q101:      1 less Heatsink              |     1 added Heatsink
CRB101:     30CTQ030                    |     MBR3035PT
C111:		470uf @ 50v             |     2200uf @ 25v

	The above info is from looking inside my 3b1 and my pc-7300. This
	was a visual only comparision. I don't have any prints for these
	units.

	NOW!!!! If only someone with Repair manuals can identify these
	parts then everyone could upgrade there pc-7300 PS :-). For the
	Q101 Heatsink you could use the black side of the old Q1 sink :-).

	Then someone would be able to start a group upgrade with the correct
	info for all those wishing to upgrade there PC-7300 PS for RAM,HD's
	more Boards, etc UPGRADES.

							Steve Urich
							WB3FTP