Tube tester problem
 

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

Tube tester problem
 

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.

Is there a fuse? Is it good?


--
Rich Greenberg N Ft Myers, FL, USA richgr atsign panix.com + 1 239 543 1353
Eastern time. N6LRT I speak for myself & my dogs only. VM'er since CP-67
Canines:Val, Red, Shasta & Casey (RIP), Red & Zero, Siberians Owner:Chinook-L
Retired at the beach Asst Owner:Sibernet-L

Tube tester problem
 

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?

Tube tester problem
 

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

Don't assume that a known good tube is still good. Test your tester
on more than one tube. If you are really lucky that will be the
problem.

Irv VE6BP

Tube tester problem
 

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?

Tube tester problem
 

Rich Greenberg wrote:
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.

Is there a fuse? Is it good?


Yes, fuse in the A.C. line and is good. Turns on with needle at center
and line voltage setting works to put it right in center. After many
years of troubleshooting and doing restorations, this is the first time
I have looked inside a tube tester. Wow, what a wiring puzzle! I had
never thought about how they work, but guess there is actually a B+,
bias, etc applied as well as filament. Then is measures gain thru the
tube? Somehow?

Tube tester problem
 

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."

Tube tester problem
 

"BillJ" wrote in message
...
Rich Greenberg wrote:
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.

Is there a fuse? Is it good?


Yes, fuse in the A.C. line and is good. Turns on with
needle at center and line voltage setting works to put it
right in center. After many years of troubleshooting and
doing restorations, this is the first time I have looked
inside a tube tester. Wow, what a wiring puzzle! I had
never thought about how they work, but guess there is
actually a B+, bias, etc applied as well as filament. Then
is measures gain thru the tube? Somehow?

There are two types of tube testers, those which measure
only filiment emmision and those which measure
transconductance. Most also test for leakage between
elements or gassy tubes. Transconductance or
mutual-conductance (different names for the same thing) have
oscillators in them and measure gain. Most also test
emission.
I am not clear on whether the tester fails with only one
tube or with any tube. If its only one tube, or one type of
tube, the chart settings may be wrong. This is pretty
common. If it fails with any kind of tube the B+ maybe dead.
I can trouble shoot some stuff without a schematic but its a
pain to say the least and you are right about tube testers
being rat's nests of wiring. If you have access to another
tester test the tube in your tester if it has one.




--
---
Richard Knoppow
Los Angeles, CA, USA

Tube tester problem
 

"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?


--
---
Richard Knoppow
Los Angeles, CA, USA

Tube tester problem
 

"Irv Finkleman" wrote in message
news:IeOgk.122078$gc5.62903@pd7urf2no...
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

Don't assume that a known good tube is still good. Test your tester
on more than one tube. If you are really lucky that will be the
problem.

Irv VE6BP

I wonder if anyone has tried to measure what voltages are there at the test
socket. Also the flip switches are most prone to loosing connection from
tarnish if there are no shorts from a wrong setup.

Test transformer. Usually some form of autotransformer. Tube inside is
likely a rectifier. Probably an emission only tester if it has only one
tube. (or multi section?)