[Amps] 3-500z - intermittent filament

[terry at g4amt.com]

Thank you to all who responded - lots been here before !
I have resoldered the filament pins of the valve and hopefully that has done 
the trick.
Just a couple of observations - the 3-500z s are not marked so I do not know 
their origin - maybe originals with this TL922 ?
The pins are riveted over on the tube side of the `former` so they cannot 
(?) be removed; they are of `split` construction. The only way  I could 
re-solder them was to use a solder sucker to extract the old solder - put a 
couple of drips of flux in the hole and re-solder with silver solder; 
heating the pin with a mini-blowlamp ...have to say not much fun and not 
really a job that you could feel 100% about .... I presume the factory would 
have a jig to heat all pins at one time and therefore remove them complete 
with the base former.
Thanks again for the help
Terry
----- Original Message ----- 
From: <terry at g4amt.com>
To: <amps at contesting.com>
Sent: Tuesday, February 06, 2007 9:54 AM
Subject: [Amps] 3-500z - intermittent filament


> My TL922 is mis-behaving with one tube operating intermittently. Symptoms
> were of open circuit filament but valve tested ok with ohm-meter and 
> worked
> when refitted. Next power up, tube failed to work. jump soldered link wire
> to pins across bases to rule out base connections. Tube worked when pin 
> and
> base `encouraged` with screwdriver.
> Looks as though previous owner has attempted to resolder the filament pins
> and I suspect a dry joint (?) within one or both filament pins.
> Is it safe to re-solder the pins ? Anything else suspicious I should be
> looking for ?
>
> Many thanks
>
> Terry
>
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