[sdiy] A simple 12AX7 vacuum tube tester schematic..

[Roy J. Tellason]

On Wednesday 16 January 2008 17:16, Matti Kari wrote:
> Hi,
>
> > The problem with this tester is that
> > for the 12AX7 the manual says:
> > GOOD if it reads 22 or more on
> > a 120 scale!! Most tested 12AX7's go
> > from 15--23..! Not quite acurate.
>
> What comes to my mind is that since your tube tester is quite old, the
> internal components may have aged and that is causing poor test results.
> It may require rebuild.

One thing that's fairly common in a lot of tube testers (though I can't speak 
to that particular model mentioned) is a rectifier inside,  which is (guess) 
a tube!  They're not particularly stressed,  and they do last a long time,  
but they do eventually age and start to deteriorate...

Just a thought.  :-)

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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