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Re: [TenTec] 262M Power Supply

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] 262M Power Supply
From: Stuart Rohre <rohre@arlut.utexas.edu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 26 Jul 2010 14:23:20 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
One of the first things to check is the diodes in the rectifier bridge.  
You may have an open bridge.
When you plug in the supply, and turn it on, do you hear hum in the 
transformer?  That would validate the transformer as receiving AC 
power.  You may have to put the ear next to the supply to tell.

The buzz might also indicate a capacitor was about to go; you pretty 
much have to do some point to point voltage measurements to find out 
what is wrong.   You can half split a problem by looking for DC voltage 
right after the bridge rectifier ta the plus side of the first filter 
cap.   Then, if you have voltage there you move toward the output, which 
might mean the regulator went.  If you don't have voltage at the plus 
side of the first cap, look back toward the bridge rectifier and 

Not getting a pilot light might indicate an AC side problem, but if the 
pilot light is 12 volt type, it would be on the 12 volt bus, which is 
probably closer to 13.4 normally.

These steps are general steps that work with any power supply circuit.  
But, if the 262M is a switcher, there could be other feedback paths that 
could shut down the supply.  A schamtic is very helpful.

-Stuart Rohre

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