3B1 power supply installation

[Karl Swartz]

Evidently Portal is having problems posting, so Thad asked me to
post this reply to my question for him.  Thanks for the info Thad!

kls at ditka.UUCP (Karl Swartz) in <20803 at ditka.UUCP> writes:

"In article <26893 at cup.portal.com> thad at cup.portal.com (Thad P Floryan) writes:
">The 3B1 supply is 245W with 5A at 12VDC, the 7300 supply is 195W with 3.5A
">at 12VDC ...
"
">1) 3B1 powers its hard drive directly from power supply; 7300 powers
">   its hard drive off the motherboard.
"
"Which reminds me, I have a 7300 and a 3B1 power supply that I'd
"like to stick in it.  I know instructions on the necessary changes
"have been posted but I can't find any copies in my archives.  Can
"somebody out there please post the instructions again?  Thanks!


Wellll, if anyone would have posted the instructions, it probably would have
been me, and I don't remember doing it.  :-)

In any event, the installation is quite simple, but "may" require soldering
depending on the options available to you.

The non-solder method requires you find a short MOLEX-MOLEX "extension cord"
to join the 4" shorty coming from the power supply to the power connector on
the hard drive.  Such "extension cords" are usually available at surplus houses
for a nominal cost (~$1.00).  Be sure to route the cable between the HD and
the metal fingers at the back of the UNIXPC case.  And be sure the sex of each
Molex connector on the extension cord is correct; one end must plug into the
cable/connector coming up from the power supply, and the other end must plug
into the HD.

The solder method requires you to make a new cable with MOLEX connector which
will run from the existing location of the cable on the power supply to the
HD.  Sometimes you can find long cables at surplus houses that already have
the correct MOLEX connector on them, then just cut the cable to the correct
length and solder it to the power supply board.

For both the above, you must cut off (i.e. remove) the HD power cable that's
presently coming up from the motherboard.  You really don't want to route power
to your HD through the motherboard; that's why the 3B1 supplies power to the HD
direct from the power supply.   Be SURE you cut off the old motherboard cable
flush to avoid any possibility of shorting to anything else.  If you have the
time, it'd be best to desolder that old existing cable.

Other than the power to the HD, the 3B1 power supply is a drop-in replacement
for the 7300 power supply.

Thad Floryan [ thad at cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]