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[AMPS] vom check of 3-500Z tubes

To: <amps@contesting.com>
Subject: [AMPS] vom check of 3-500Z tubes
From: 2@vc.net (2)
Date: Fri, 5 Oct 2001 11:59:33 -0700
>
>Jim Spears" said: 
>> 
>> >
>> >> my amp supply lk-500 zb did a funny thing a while back when I powered
>> >> it up after a long time in the closet and a cross country move.  so
>> >> far I have found a blown 1 ohm, 5 watt wire wound resistor.  it was in
>> >> two pieces so there is little debate on whether or not it blew...
>
>I am one of the least experienced amplifier debuggers on the reflector 
>having 
>only debugged and repaired five HF amplifiers (some more than once due to 
>severe contest quest-op abuse). I have spent a great deal of time however 
>troubleshooting other electronic things in my career.
>
>I try to start with an open mind to the problem. Root cause determination is 
a 
>methodical process. Analyze the failure and then take the simplest and least 
>expensive steps first working toward the more expensive and exotic. In this 
>case DC check the tubes, look for obvious arcing or a discharge path, inspect 
>and measure critical components in the path. Then replace the resistor and 
try 
>again! Dust, bugs, errant shards of solder, etc. could surely trigger the 
>disappearing glitch resistor trick. Doesn't it make sense after following the 
>steps above to just replace the resistor and fire the rig up again? Then take 
>the next step.
>
>I stand ready to be corrected!
>
//  Such is a good approach.  My experiences suggest that when a 
component blows, there is a chance that it wasn't because the component 
was defective.  In other words, something else could have made it blow.  
For example, replacing a blown fuse seldom fixes the problem unless one 
investigates and finds out Why the fuse blew.  
-  A blown glitch resistor means that the manufacturer may not have 
performed the necessary short B+ to gnd test. 

 cheers, Ron

-  R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.  
end


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