Making defender power supply adjustable

From: David Shoemaker <>
Date: Mon Sep 19 2011 - 01:55:45 EDT

I have an original defender PS that has drifted a bit. I remember there
being a fix for this in replacing one of the resistors with a 5K adjustable
so you could tweak out the small drift.


I have done this on a few of these over the years but every time I have had
to dig to find the information on which resistor to replace. I hate analog
J And now this time I just can't find the info.


I am pretty sure looking at the schematic that I want to replace R1 a 4990
1% resistor which connects to IC1 as part of a voltage divider between gnd
and vref.


Or it could be R2 (2.15k 1% the other half the divider) which would be
easier to do on the board as it's on the end of a row of components.


Can anyone check me for stupid before I make the mod?




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Received on Mon Sep 19 01:56:10 2011

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