On 7/20/08 2:45 PM, in article , "BillJ"
wrote:

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?

It could be the rectifier(s), could be a DC amplifier, or both. Pull the
tube out and put it your freezer/refrigerator about 15 minutes. If you
still can't read the number accurately, then blow on it gently as if you
were trying to warm very cold hands. This should bring up the numbers.

(If it is a 117L7 it has a diode and a pentode)

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?

In this case, it's woops! I meant "it's manual."