"BillJ" wrote in message
...
Don Bowey wrote:
On 7/20/08 12:57 PM, in article
, "BillJ"
wrote:

I have Sylvania Electric tube tester. Has worked for
many years, but
today known good tube test flat zero. Filaments do
light. I have no
model number, it is a green panel, with roll chart.

Anybody know what might go wrong. I looked inside and
see one tube, a
1EL7 I think it was. Other wise looks good, with no bad
smells.

Thanks, Bill

Check the Meter Movement with a very low voltage and lots
of resistance.

Set the tester up for a few tubes, one at a time, and
measure the voltages
at the pins. Trace back to source of missing voltages.
Wiggle the pots for
affect.

A tube manual will suggest what voltage to expect.

There are probably at least two DC power supplies in the
tester. Check them
for input and output voltages. Depending on the vintage
of the tester you
may have selenium rectifiers that have a too high
internal resistance. Don'
forget to test the capacitors for shorts.

And don't forget.........The internal toob might be shot.
Seeing a filament
glow does not a good tube make.

Neither my Sylvania tube manual nor a Google search list
a 1EL7.

Have you looked for ti's manual?

Thanks for the tips: meter movement works on line voltage
set at mid scale, so don't think thats the problem. Any
idea what the internal tube is for? I don't see a filament
glow, but it's only a 1 Volt,
May have the tube number wrong.
What is the "ti" manual?

The tube is probably an oscillator meaning the tester is
the mutual-conductance type which actually tests
amplification rather than just filiment emission.
Are you sure you are reading the tube type correctly?


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Richard Knoppow
Los Angeles, CA, USA