>
>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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