Output transformer ambiguity
Steve Sousa
I have a tube radio to repair. It's output valve is an ELL80 (two EL95 in
one tube) and was broken at the base and the socket showed signs of overheat
and cold solder joints. I have the valve on order but when checking the
output transformers (it has 2) onde of them has a primary resistance of
~900ohm and the other ~4000 ohm. I measured the turns ratio using a signal
generator at 1khz and got 45,6 and 46,0 which squared and multiplied by the
speakers output impedance (5ohm) gives ~10kohms which is the expected
impedance for the ELL80. Given all this info how can i check which
transformer is bad? they both drive an speaker just fine using the Sig. Gen.
but i can't believe they can have such different dc resistance.
Thank you in advance
Best Regards
Steve Sousa
Meat Plow
That's a heck of a difference in DC resistance. If you drive both with a
sig generator and look at the secondaries on a scope is there a big
difference in the signal amplitude between the two? If not I would be
inclined to replace the tube and take some voltages while the circuit is
live while monitoring the plate currents. You can look here for
operational voltages and currents in different classes of operation:
http://www.nj7p.org/Tube4.php?tube=6gu8
--
Live Fast, Die Young and Leave a Pretty Corpse
Phil Allison
"Steve Sousa"
>
> I have a tube radio to repair. It's output valve is an ELL80 (two EL95 in
> one tube) and was broken at the base and the socket showed signs of
> overheat and cold solder joints. I have the valve on order but when
> checking the output transformers (it has 2) onde of them has a primary
> resistance of ~900ohm and the other ~4000 ohm.
** Assuming the transformers are the same size and do the same job, the one
with the 4000 ohm primary is stuffed.
> I measured the turns ratio using a signal generator at 1khz and got 45,6
> and 46,0
** Do not use a comma for the decimal point - it is way too confusing.
..... Phil
Brenda Ann
"Phil Allison" wrote in message news:8l2puj...@mid.individual.net...
..... Phil
--------------------------------------------------------------------------------
Most of the world uses a comma as a decimal point. The US and Canada are
about the only ones that use a period.
Phil Allison
"Brenda Ann"
"Phil Allison"
>
> "Steve Sousa"
>>
>> I have a tube radio to repair. It's output valve is an ELL80 (two EL95 in
>> one tube) and was broken at the base and the socket showed signs of
>> overheat and cold solder joints. I have the valve on order but when
>> checking the output transformers (it has 2) onde of them has a primary
>> resistance of ~900ohm and the other ~4000 ohm.
>
>
> ** Assuming the transformers are the same size and do the same job, the
> one
> with the 4000 ohm primary is stuffed.
>
>
>> I measured the turns ratio using a signal generator at 1khz and got 45,6
>> and 46,0
>
>
> ** Do not use a comma for the decimal point - it is way too confusing.
>
>
>
> Most of the world uses a comma as a decimal point.
** Bullshit.
>The US and Canada are about the only ones that use a period.
** Virtually the entire English speaking world uses the period.
..... Phil
Meat Plow
> Bullshit.
Regarded as you most affluent reply :)
Brenda Ann
"Phil Allison" wrote in message news:8l30ju...@mid.individual.net...
> ** Do not use a comma for the decimal point - it is way too confusing.
>
>
>
> --------------------------------------------------------------------------------
> Most of the world uses a comma as a decimal point.
** Bullshit.
>The US and Canada are about the only ones that use a period.
** Virtually the entire English speaking world uses the period.
..... Phil
--------------------------------------------------------------------------------
Countries where a comma is used to mark the radix point include:
Albania, Andorra, Argentina, Austria, Azerbaijan, Belarus, Belgium, Bolivia,
Bosnia and Herzegovina, Brazil, Bulgaria, Cameroon, Canada
(French-speaking), Costa Rica, Croatia (comma used officially, but both
forms are in use elsewhere), Chile, Colombia, Cuba, Cyprus, Czech Republic,
Denmark, Dominican Republic, Ecuador, El Salvador, Estonia, Faroes, Finland,
France, Germany, Greece, Greenland, Guatemala, Honduras, Hungary, Indonesia,
Iceland, Italy, Kazakhstan, Latvia, Lithuania, Luxembourg (uses both
separators officially), Macedonia, Moldova, Netherlands, Norway, Nicaragua,
Panama, Paraguay, Peru, Poland, Portugal, Romania, Russia, Serbia, Slovakia,
South Africa (officially, but dot point is commonly used in business, even
though South Africa used to be in the British Empire, which is considered to
be strange by quite a few people in Britain), Slovenia, Spain, Sweden,
Switzerland, Turkey, Ukraine, Uruguay, Venezuela, Vietnam.
Phil Allison
"Brenda Ann is another autistic fuckwit"
> Most of the world uses a comma as a decimal point.
** Bullshit.
>The US and Canada are about the only ones that use a period.
** Virtually the entire English speaking world uses the period.
----------------------------------------------------------------------
Thank you for your post that proved the above point beyond any doubt.
..... Phil
Sjouke Burry
Netherlands uses the comma only in text,
never to indicate fractions.
David Nebenzahl
> Brenda Ann wrote:
>
>> "Phil Allison" wrote in message news:8l30ju...@mid.individual.net...
>>> ** Do not use a comma for the decimal point - it is way too confusing.
>>>
>>> --------------------------------------------------------------------------------
>>> Most of the world uses a comma as a decimal point.
>>
>> ** Bullshit.
>>
>>> The US and Canada are about the only ones that use a period.
>>
>>
>> ** Virtually the entire English speaking world uses the period.
>>
>> Countries where a comma is used to mark the radix point include:
>>
>> Albania, Andorra, Argentina, Austria, Azerbaijan, Belarus, Belgium, Bolivia,
>> Bosnia and Herzegovina, Brazil, Bulgaria, Cameroon, Canada
>> (French-speaking), Costa Rica, Croatia (comma used officially, but both
>> forms are in use elsewhere), Chile, Colombia, Cuba, Cyprus, Czech Republic,
>> Denmark, Dominican Republic, Ecuador, El Salvador, Estonia, Faroes, Finland,
>> France, Germany, Greece, Greenland, Guatemala, Honduras, Hungary, Indonesia,
>> Iceland, Italy, Kazakhstan, Latvia, Lithuania, Luxembourg (uses both
>> separators officially), Macedonia, Moldova, Netherlands, Norway, Nicaragua,
>> Panama, Paraguay, Peru, Poland, Portugal, Romania, Russia, Serbia, Slovakia,
>> South Africa (officially, but dot point is commonly used in business, even
>> though South Africa used to be in the British Empire, which is considered to
>> be strange by quite a few people in Britain), Slovenia, Spain, Sweden,
>> Switzerland, Turkey, Ukraine, Uruguay, Venezuela, Vietnam.
>>
> Did you collect country names at random?
> Netherlands uses the comma only in text,
> never to indicate fractions.
But we're not talking about fractions; we're talking about decimals.
Or are those terms equivalent in your country?
--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.
- Comment from an article on Antiwar.com (http://antiwar.com)
Michael A. Terrell
Brenda, you're wasting your time trying to converse with Phil. He is
a mentally ill character in Australia, who frequently stops taking his
medication.
--
For the last time: I am not a mad scientist, I'm just a very ticked off
scientist!!!
Sjouke Burry
That still does not explain the random selection of country's,
unless one really likes to conduct a shitty discussion.
Brenda Ann
"Sjouke Burry" wrote in message
news:4cec9045$0$8923$703f...@textnews.kpn.nl...
>>> Countries where a comma is used to mark the radix point include:
>>>
>>> Albania, Andorra, Argentina, Austria, Azerbaijan, Belarus, Belgium,
>>> Bolivia, Bosnia and Herzegovina, Brazil, Bulgaria, Cameroon, Canada
>>> (French-speaking), Costa Rica, Croatia (comma used officially, but both
>>> forms are in use elsewhere), Chile, Colombia, Cuba, Cyprus, Czech
>>> Republic, Denmark, Dominican Republic, Ecuador, El Salvador, Estonia,
>>> Faroes, Finland, France, Germany, Greece, Greenland, Guatemala,
>>> Honduras, Hungary, Indonesia, Iceland, Italy, Kazakhstan, Latvia,
>>> Lithuania, Luxembourg (uses both separators officially), Macedonia,
>>> Moldova, Netherlands, Norway, Nicaragua, Panama, Paraguay, Peru, Poland,
>>> Portugal, Romania, Russia, Serbia, Slovakia, South Africa (officially,
>>> but dot point is commonly used in business, even though South Africa
>>> used to be in the British Empire, which is considered to be strange by
>>> quite a few people in Britain), Slovenia, Spain, Sweden, Switzerland,
>>> Turkey, Ukraine, Uruguay, Venezuela, Vietnam.
>>>
>> Did you collect country names at random?
>> Netherlands uses the comma only in text,
>> never to indicate fractions.
>
> But we're not talking about fractions; we're talking about decimals.
>
> Or are those terms equivalent in your country?
>
>
Decimal is a type of fraction.
That still does not explain the random selection of country's,
unless one really likes to conduct a shitty discussion.
--------------------------------------------------------------------------------
The list is not random, and is found on many sites regarding finance, etc.
The site this particular list is from is:
http://www.worldlingo.com/ma/enwiki/en/Decimal_separator#Comma_countries
David Nebenzahl
> David Nebenzahl wrote:
>
>> On 11/23/2010 6:35 PM Sjouke Burry spake thus:
>>
>>> Netherlands uses the comma only in text,
>>> never to indicate fractions.
>>
>> But we're not talking about fractions; we're talking about decimals.
>>
>> Or are those terms equivalent in your country?
>>
> Decimal is a type of fraction.
Technically, yes. But if you say (or write) "fraction", most English
speakers expect something in the form x/y, not x.y or x,y.
In other words, decimals are special cases of fractions, with their own
formatting.
Phil Allison
"Brenda Ann" is an another ASD fucked IDIOT "
>
> "Sjouke Burry" wrote in message
>>>>
>>>> Albania, Andorra, Argentina, Austria, Azerbaijan, Belarus, Belgium,
>>>> Bolivia, Bosnia and Herzegovina, Brazil, Bulgaria, Cameroon, Canada
>>>> (French-speaking), Costa Rica, Croatia (comma used officially, but both
>>>> forms are in use elsewhere), Chile, Colombia, Cuba, Cyprus, Czech
>>>> Republic, Denmark, Dominican Republic, Ecuador, El Salvador, Estonia,
>>>> Faroes, Finland, France, Germany, Greece, Greenland, Guatemala,
>>>> Honduras, Hungary, Indonesia, Iceland, Italy, Kazakhstan, Latvia,
>>>> Lithuania, Luxembourg (uses both separators officially), Macedonia,
>>>> Moldova, Netherlands, Norway, Nicaragua, Panama, Paraguay, Peru,
>>>> Poland, Portugal, Romania, Russia, Serbia, Slovakia, South Africa
>>>> (officially, but dot point is commonly used in business, even though
>>>> South Africa used to be in the British Empire, which is considered to
>>>> be strange by quite a few people in Britain), Slovenia, Spain, Sweden,
>>>> Switzerland, Turkey, Ukraine, Uruguay, Venezuela, Vietnam.
>>>>
>>> Did you collect country names at random?
>>> Netherlands uses the comma only in text,
>>> never to indicate fractions.
>>
>> But we're not talking about fractions; we're talking about decimals.
>>
>> Or are those terms equivalent in your country?
>>
>>
> Decimal is a type of fraction.
** Bollocks #2
> That still does not explain the random selection of country's,
** Noting *random* about that selection of NON English speaking countries
- you lying pile of ASD fucked dung.
.... Phil
Smitty Two
Sjouke Burry <burrynu...@ppllaanneett.nnll> wrote:
> That still does not explain the random selection of country's,
> unless one really likes to conduct a shitty discussion.
I guess those are the same countries where the plural of country is
country's.
N_Cook
news:K9udnSQtW4kL2XHR...@giganews.com...
If the 4000 ohm one is shot then it should vary considerably with heating
and knocking. Hot air gun and a mallet. What is the amp ? (sorry if included
in the unread usual threaded diahrhoea)
N_Cook
unlikely to change with heat and/or vibration
Steve Sousa
"Phil Allison" <phi...@tpg.com.au> wrote in message
news:8l2puj...@mid.individual.net...
>
>
> ** Assuming the transformers are the same size and do the same job, the
> one with the 4000 ohm primary is stuffed.
>
>
>> I measured the turns ratio using a signal generator at 1khz and got 45,6
>> and 46,0
>
>
> ** Do not use a comma for the decimal point - it is way too confusing.
>
>
>
> ..... Phil
>
Hello
Wouldn't it be possible to have an original 4000ohm shorted to 900ohm too?
Best Regards
Steve Sousa
"N_Cook" <div...@tcp.co.uk> wrote in message
news:icijdo$d1a$1...@news.eternal-september.org...
> If the 900 ohm one was shot then it implies some shorted turns that is
> unlikely to change with heat and/or vibration
>
>
Hello:
the amp is a grundig como e/st, you can see a picture and the schematic at
http://meuble.radio.free.fr/stereo_console/grundig/index.html
i haven't removed the transformers because they are soldered to the chassis!
(the metal bracket is soldered to the chassis *and* the pcb)
Steve Sousa
"Meat Plow" <mhy...@yahoo.com> wrote in message
news:pan.2010.11...@lmao.lol.lol...
hello:
there was about half division difference on the scope. I was trying to avoid
testing with the valve because it's expensive and "rare" i don't want to
take much risks....
N_Cook
news:4cee6eaa$0$61360$892e...@auth.newsreader.octanews.com...
Do the 2 in one output valves mean the amp is compact size?
I know an intermittent break in low impedance side of output Tx can lead to
valve failure but does intermittant high imp side harm the drive valves?
The Tx numbers matching on that schematic confirms they should be to within
about 5 percent the same measurements
Jeff Layman
Are these of any use:
http://www.vvttransformers.co.uk/vtp135200.htm
http://www.vvttransformers.co.uk/vtp206300.htm
--
Jeff
Phil Allison
"Steve Sousa"
> "Phil Allison"
>>
>> ** Assuming the transformers are the same size and do the same job, the
>> one with the 4000 ohm primary is stuffed.
>>
>>
>>> I measured the turns ratio using a signal generator at 1khz and got 45,6
>>> and 46,0
>>
>>
>> ** Do not use a comma for the decimal point - it is way too confusing.
>>
>
** No.
The ratio between rated primary Z and winding resistance is never less than
5:1 and is typically 10:1 or more.
.... Phil
David Nebenzahl
> "Steve Sousa" wrote:
>
>> "Phil Allison" wrote:
>>>
>>> ** Assuming the transformers are the same size and do the same job, the
>>> one with the 4000 ohm primary is stuffed.
>>
>> Wouldn't it be possible to have an original 4000ohm shorted to 900ohm too?
>
> ** No.
>
> The ratio between rated primary Z and winding resistance is never less than
> 5:1 and is typically 10:1 or more.
You may have a point there.
OK, let's climb down into N. Cook's pit of bodgery and post mortem
analysis and look at this.
It all depends on the expected failure mode of a transformer, correct?
Two main possibilities here: open windings, or shorted windings (or I
suppose a combination). Obviously not an open winding, so probably
shorted ones.
Shorted windings could be within the primary or secondary, or between.
Let's look at the simpler case, shorted within the primary, which should
be 4K ohms.
It seems most likely that any short would be between adjacent layers of
windings. Not likely that there'd be a short from close to one end to
close to the other end. Which should limit the effect of the short. So
if the 4K ohm primary is now 900 ohms, there's something else going on.
But what? Could there be a short from the winding to the iron core?
Has the O.P. checked for a short between primary and secondary? How
about shorts to the core/frame of the xfmr?
Phil Allison
"David Nebenzahl = Idiot "
>>
>>> Wouldn't it be possible to have an original 4000ohm shorted to 900ohm
>>> too?
>>
>> ** No.
>>
>> The ratio between rated primary Z and winding resistance is never less
>> than 5:1 and is typically 10:1 or more.
>
> You may have a point there.
>
> OK, let's climb down into N. Cook's pit of bodgery and post mortem
> analysis and look at this.
>
> It all depends on the expected failure mode of a transformer, correct? Two
> main possibilities here: open windings, or shorted windings (or I suppose
> a combination). Obviously not an open winding, so probably shorted ones.
** Shame about the third and most likely scenario - one that makes the
primary R go way high.
Think " vertigris " .....
..... Phil
N_Cook
news:4cee6eaa$0$61360$892e...@auth.newsreader.octanews.com...
>
>
What is the result of hot-air heating and knocking the transformers with
copper/hide hammer or simulating with hammer and wood block while monitoring
the ohms?
Certainly don't power up with new valve without using a variac and probably
filament bulb telltales(acting as fuse if serious problem) in place , if you
cannot establish which Tx is wonky.
N_Cook
knocking fails to show any variation. Shorted turns tend to be "welded"
together . I only have test data for the EL80 but 25mA per pentode and
looking at some Premier Tx data for range of use 7 watt to 60W, DC of HT
side ranging from 1500 to 16000 ohm so 4000 ohm seems more likely.
What is the physical dimensions of your ones?
David Nebenzahl
You mean *verdigris*.
So that could happen if the insulation got nicked and moisture gets in,
corroding the wire. How does that work? Narrow the wire and increase the
resistance (eventually causing an open)?
Phil Allison
"David Nebenzahl"
Phil Allison
>
>> ** Shame about the third and most likely scenario - one that makes the
>> primary R go way high.
>>
>> Think " vertigris " .....
>
> You mean *verdigris*.
>
> So that could happen if the insulation got nicked and moisture gets in,
> corroding the wire. How does that work? Narrow the wire and increase the
> resistance (eventually causing an open)?
** Can happen any number of ways including at the termination points of the
enamelled wire where it is soldered to a flying lead. Solder flux is then
the trigger and moisture from the air can get to it.
The high resistance is because for some small distance, conduction is via
the verdigris.
.... Phil