david axt

I had a problem with one of my Fender amps. I checked all the tubes on the tube tester and they were fine. So just for laughs I started substituting tubes before I ripped into the guts of the amp. Well wouldn't you know that I found a bad 12AU7 tube. I put it back in and got crackling and hum. Tested it and it was good. Put it in another amp and got crackling and hum.

So I guess the moral of the story is that tube testers only work for some tests and does not catch all the problems.

David

phil allison

So I guess the moral of the story is that tube testers only work for some tests and does not catch all the problems.

** That is for sure.

A tube must be tested the same way it is going to be used - the voltages on the plate, current levels, grid impedances etc must all match the application.

The amp itself is a tube tester - the best one out.

.................. Phil

td madden

How about one of those "Maxi-Testers"?

phil allison

** Top posters get no answers.

phil allison

** Go do a Google search.


** Drivel.


** There is NO logic to top posting.

It is not a method - it is an attitude.

.............. Phil

lord valve

You're an ignorant Aussie cunt.
LV

phil allison

"Lord Valve" <detritus@ix.netcom.com> wrote in message news:3EFBDF5F.144A64CB@ix.netcom.com...

** Then by comparison you are the devil incarate.

............. Phil

lord valve

See? Top posters *do* get answers.

Especially from ignorant Aussie cunts.

Lord Valve
American

robert m. braught

'Not the same' unless you've got all the knobs in the right place; don't
discount lab stuff and methods (see below.)

But my oft repeated response to tester inquiries echos something like
you said, Phil, that "the best tube 'tester' is the equipment that will
be using the tube in question."


If you sent me one or two I'll test them and tell you. I promise I won't
'cheat' and use an amp chassis.


An easier test in an amp, indeed. But lab stuff can be configured to
stroke that bottle to destruction, replicating any operating
condition... I don't have all the stuff (yet!) to thoroughly do all the
methods in the US Dept. of Defense MIL-STD-1311C, or the desire at this
time to pay someone to sit and operate dedicated test equipment when the
customer's equipment is handy.

"...I know I put that accelerometer somewhere!"


The testers/curve tracers I was referring to can be configured for
destructive testing, getting envelope glass hot enough for implosion:
hot enough for ya?

Cheers,
-Robert
QTS
http://www.Braught.com

td madden

You mean like unhelpful jerks?

It was a rhetorical question anyway, as those devices use high voltage
for testing....and there are probably some folks here with an interest
in something besides unhelpful chiding.