Power Supplies 7300<==> 3B1

[kenneth.p.stox]

Well, first of all, many thanks for Thad for announcing the availability
of those 3B1/7300 Power Supplies to the net. It turns out by finally
upgrading my machine to a 3B1 supply, I narrowly averted disaster.

Here is the scenario:

	7300 1/2 Meg RAM on board
	7300 Power Supply
	2 Meg RAM Card
	DOS-73 w/8087-2
	Voice Power
	Original drive replaced with a ST4096

I've been running this configuation (minus Voice Power, [ Thanks Lenny ! ] )
for about two years now. Although there was a little bit of screen waviness,
everything else was acceptable, or so I thought. In the past few months,
however, I was having intermittent problems booting. I assumed this problem
was my hard drive preparing to flake out.

This weekend, I decided to install one of the 3B1 power supplies, and in the
process of doing so, found out the following:

	1) The connector from the ribbon cable to the power supply crumbled
	in my hands. The underside of the 5volt crimp connections were
	darkened and most of the plastic had decayed. Obviously, the
	connector had been running too hot, for a while.

	2) As you all probably know by now, the 3B1 supply has a separate
	connector for the hard drive. [[ Wonder Why ?? :-) ]] So, I
	installed the new supply, and cabled up the Hard Drive directly
	to the power supply, and all is well.

LESSONS:

	1) Although I was not exceeding the abilities of either the 
	power supply or main logic board power traces, I was, in fact,
	exceeding the current limitations of the crimp connector.

	2) If you are running a larger hard drive (ie. a drive with
	larger current demands ), I would recommend installing either
	a 3B1 style supply, or soldering your hard drive power connections
	directly to the supply. I will say, however, that just the ST4096
	was not the final factor, although the damage was probably being
	done to a lessor degree. The addition of the voicepower board
	was probably the straw that broke the camel's back.

EPILOGUE:

	Last of all, my humble thanks to Craig Votava, whose help
	is always greatly appreciated.


	Ken Stox
	att!ihlpb!stox
	att!cbnewsc!stox