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Smelly Tellies



 
 
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  #11  
Old January 22nd 17, 09:14 AM posted to uk.tech.digital-tv
Indy Jess John
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Posts: 1,046
Default Smelly Tellies

On 22/01/2017 02:14, Graham. wrote:
On Sat, 21 Jan 2017 20:39:50 -0000, "Brian Gaff"
wrote:

Well yes, and the Decca colour sets had a unique smell from their
convergence pcbs when new as I recall.

And who can forget that smell of ozoone when the room was full of
condensation and you switched on the tv. Photocopiers and laser printers are
the only things that smell like that unless you have one of those once
trendy ionisers.


Brian


Trendy? Grandpa had an ioniser in the 1950s. A big Bakelite thing with
a lethal transformer inside.



I bought one of those at a car boot sale, many years ago.
It was a step-up transformer - mains in, and a rectified 24,000 volts on
the output side.

I wrecked one voltmeter trying to measure that, and eventually made a
resistor bridge so that I could measure a known part of the voltage
within the scale of my replacement meter and then multiply it up.

I decided it was too dangerous to use, and put it in the attic because
it will eventually become an antique, worth more than the 2 I paid for it.

Jim

  #12  
Old January 22nd 17, 05:52 PM posted to uk.tech.digital-tv
Benderthe.evilrobot
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Posts: 148
Default Smelly Tellies


"Graham." wrote in message
...
On Sat, 21 Jan 2017 20:39:50 -0000, "Brian Gaff"
wrote:

Well yes, and the Decca colour sets had a unique smell from their
convergence pcbs when new as I recall.

And who can forget that smell of ozoone when the room was full of
condensation and you switched on the tv. Photocopiers and laser printers
are
the only things that smeel like that unless you have one of those once
trendy ionisers.


Brian


Trendy? Grandpa had an ioniser in the 1950s. A big Bakelite thing with
a lethal transformer inside.


Early TVs had a mains EHT transformer - it took them a while to figure out
how to generate EHT from the flyback pulses, it pretty much happened by
accident while they were trying to improve efficiency in the horizontal scan
section.

EHT for those early B&W sets was usually between 6 & 12kV - enough current
from the secondary for instant death.

A microwave oven transformer shoves 2kV into the voltage doubler - I think
they're good for about 1/2A.

  #13  
Old January 23rd 17, 09:00 PM posted to uk.tech.digital-tv
Graham.[_12_]
external usenet poster
 
Posts: 381
Default Smelly Tellies

On Sun, 22 Jan 2017 18:52:59 -0000, "Benderthe.evilrobot"
wrote:


"Graham." wrote in message
.. .
On Sat, 21 Jan 2017 20:39:50 -0000, "Brian Gaff"
wrote:

Well yes, and the Decca colour sets had a unique smell from their
convergence pcbs when new as I recall.

And who can forget that smell of ozoone when the room was full of
condensation and you switched on the tv. Photocopiers and laser printers
are
the only things that smeel like that unless you have one of those once
trendy ionisers.


Brian


Trendy? Grandpa had an ioniser in the 1950s. A big Bakelite thing with
a lethal transformer inside.


Early TVs had a mains EHT transformer - it took them a while to figure out
how to generate EHT from the flyback pulses, it pretty much happened by
accident while they were trying to improve efficiency in the horizontal scan
section.

EHT for those early B&W sets was usually between 6 & 12kV - enough current
from the secondary for instant death.

A microwave oven transformer shoves 2kV into the voltage doubler - I think
they're good for about 1/2A.


Throughout the '70s and 80's my day job was mending tellys. I never
got to work on one with mains derived EHT, they were genrally speaking
pre-war. I also had a job that included fixing a lot of microwave
ovens.

I recently restored a 1949 vintage TV set for fun, it has a mains
energised loudspeaker magnet and a round CRT but a fairly conventional
flyback EHT system.




--

Graham.

%Profound_observation%
  #14  
Old January 23rd 17, 09:21 PM posted to uk.tech.digital-tv
Benderthe.evilrobot
external usenet poster
 
Posts: 148
Default Smelly Tellies


"Graham." wrote in message
...
On Sun, 22 Jan 2017 18:52:59 -0000, "Benderthe.evilrobot"
wrote:


"Graham." wrote in message
. ..
On Sat, 21 Jan 2017 20:39:50 -0000, "Brian Gaff"
wrote:

Well yes, and the Decca colour sets had a unique smell from their
convergence pcbs when new as I recall.

And who can forget that smell of ozoone when the room was full of
condensation and you switched on the tv. Photocopiers and laser printers
are
the only things that smeel like that unless you have one of those once
trendy ionisers.


Brian

Trendy? Grandpa had an ioniser in the 1950s. A big Bakelite thing with
a lethal transformer inside.


Early TVs had a mains EHT transformer - it took them a while to figure out
how to generate EHT from the flyback pulses, it pretty much happened by
accident while they were trying to improve efficiency in the horizontal
scan
section.

EHT for those early B&W sets was usually between 6 & 12kV - enough current
from the secondary for instant death.

A microwave oven transformer shoves 2kV into the voltage doubler - I think
they're good for about 1/2A.


Throughout the '70s and 80's my day job was mending tellys. I never
got to work on one with mains derived EHT, they were genrally speaking
pre-war. I also had a job that included fixing a lot of microwave
ovens.

I recently restored a 1949 vintage TV set for fun, it has a mains
energised loudspeaker magnet and a round CRT but a fairly conventional
flyback EHT system.


The only vintage telly I ever tackled was more recent than that - every
fault I fixed was rapidly followed by a new unrelated fault.

Not an experiment I was keen to repeat........................

Flyback recovery continued to evolve right from day one - But I'd have to
say the development of fast enough semiconductors was the biggest
evolutionary step.

In my early days - I tried replacing a CTV damper diode with a string of
regular silicon type, and watched in amazement as it went limp and floppy as
all the solder joints melted.

 




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