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Switching power supply for TI 99/4A [message #79220] Sun, 02 June 2013 23:14
nessus is currently offline  nessus
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Message-ID: <2394@nsc.UUCP>
Date: Mon, 25-Feb-85 21:45:44 EST
Article-I.D.: nsc.2394
Posted: Mon Feb 25 21:45:44 1985
Date-Received: Tue, 26-Feb-85 23:39:07 EST
Distribution: na
Organization: The Patriarchy of Kzin, Kzin
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[I saw a lovely flash in the computer. Are electrons really blue?]
[I saw a lovely flash in the computer. Are electrons really blue?]

     Last week while in a San Francisco Bay area Radio Shack(Yes, I admit it!)
I ran across a package labelled "SWITCHING POWER SUPPLY CHASSIS".  The AC line
connector looked familiar, but I didn't think anything of it.  Over the weekend
while visiting a friend who has a TRS Color Computer, I happened to look
through her latest TRS flyer and found the following:

     SWITCHING POWER SUPPLY CHASSIS from TI 99/4 Computer.  Cool-running
     supply puts out +12VDC@400mA,+5VDC@1.2A, and -5VDC@200mA.  Input
     18VAC@1.2A.  Great for ...(the usual)  Price $4.95 .

     I have one of the beasties sitting in front of me right now.  The board
looks the same size as the one I pulled out of my console last August, but the
parts layout is different(obviously).  The board uses only two of the inputs
from the transformer; I believe my old TI supply used three of the inputs.

     Has anyone tried to put one of these in a 99/4(A) yet?  If so, is it really
cooler than a TI supply?  As I'm sure most of you TIers know, that area just
under the cartridge port can get pretty hot.  Last August my -5V regulator died
and took most of the computer with it.  I suspect that the regulator, a 7905
three-terminal type, overheated and went to 0V.  Since then I have put a fan on
the table[with duct-tape(tm)!] pointing into the slots near the power switch. I
have not had any trouble with overheating; I have run the computer all day and
not had any problems(except typos!).  But the fan gets in the way quite
frequently, and so would like to try this new board out.

     Also, for anyone interested, TRS also has beige TI 99/4A keyboards < ~$5
if memory serves me correctly.
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