[TenTec] Rsc value for LM723 in 280/255 power supplies?

[Clayton Brantley]

Sounds like the "normal" way for a '723 supply to die.  I would keep the power transformer
IF it's  ok, then build a supply using the 7815 regulator controlling the base of a darlington
pair.  K4EAJ (SK) used this supply for all his repeaters for may years without any failures.
The saving grace is when a '78xx regulator faults, it shuts down vice going to the max +v
rail as the '723's do.  Another neat thing is the parts count is less.  I have been using three os
these supplies for over 15 years and never a hicup.  I might have the circuit that I could copy 

and email to you if you would like.

Clayton N4EV



________________________________
 From: Peter Bertini <radioconnection at gmail.com>
To: tentec at contesting.com 
Sent: Saturday, June 2, 2012 1:07 PM
Subject: [TenTec] Rsc value for LM723 in 280/255 power supplies?
 
Hello to the group

I'm in the processing of rescuing a much abused TenTec 280 power supply.
There is no amp meter on the front, but it has the speaker, so
I assume it may be a model 255 despite what the label shows.

The supply had major problems. Most the transistors were shorted, as well
as the
LM-723 regulator IC. The .62 ohm resistor (Rsc) was also vaporized. I'm
curious
what this part was used for?  I assume that 13.8/0.62    means that the
this resistor
set the maximum available current at 22 amps?  If so, is the adjustable
current pot
a second over current setting that works independently for setting a lower
max.
current output for this supply?

regards

Pete
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