Freeview blowing crt sets ?

Stefan wrote:
I have a Sony crt about 15 years old

They don't last forever you know.

(My VEGA 32" Widescreen CRT only lasted 12 years 1999-2007 - R.I.P)

On Wed, 15 Apr 2009 11:30:20 +0100, jon.in.durham wrote:

(My VEGA 32" Widescreen CRT only lasted 12 years 1999-2007 - R.I.P)

Something does not compute.

"jon.in.durham" wrote in message
...
Stefan wrote:
I have a Sony crt about 15 years old

They don't last forever you know.

(My VEGA 32" Widescreen CRT only lasted 12 years 1999-2007 - R.I.P)



My Sony was not quite new when bought it ex rental - it lasted from ~1982 -
1997.

It was fine until just before the end when I stupidly watered a vase of
flowers on top of it and spilled some down the inside. It took days to dry
it out, but it did work again, while I completed purchase of a replacement
Philips. This is still going with an excellent picture, although I am
thinking seriously about a new 1080 HD set.

charles wrote:
In article ,
Bill wrote:
In message , charles
writes
I am aware that some sets used to go into audio mute when there was an
excessive amount of hf on the sound. This gave rise to what was known
as 'The Angela Ripon Effect' where these sets muted when she started to
talk. She had excessive high frequencies in her voice and the line to
Crystal Palce was good to 23kHz. Could this be something similar?

A TV that blows up when it sees Angela Rippon?

no, the sound muted when it heard her.


Now that would be a useful feature, especially if
there was a selectable menu e.g. David Cameron, Gordon
Ramsay, (add your own annoying celebrity)

....snip...

I've had a old Sony "die" from dry joints. A local repair shop fixed it for
about 50quid.

Paul DS.

On 16 Apr, 12:35, Jim wrote:
charles wrote:
In article ,
* *Bill wrote:
In message , charles
writes
I am aware that some sets used to go into audio mute when there was an
excessive amount of hf on the sound. *This gave rise to what was known
as 'The Angela Ripon Effect' where these sets muted when she started to
talk. She had excessive high frequencies in her voice and the line to
Crystal Palce was good to 23kHz. *Could this be something similar?

A TV that blows up when it sees Angela Rippon?

no, the sound muted when it heard her.

Now that would be a useful feature, especially if
there was a selectable menu e.g. David Cameron, Gordon
Ramsay, (add your own annoying celebrity)

David Cameron's a celebrity?
Cheesus. When did *that* happen?

Mike wrote:
On 16 Apr, 12:35, Jim wrote:
charles wrote:
In article ,
Bill wrote:
In message , charles
writes
I am aware that some sets used to go into audio mute when there was an
excessive amount of hf on the sound. This gave rise to what was known
as 'The Angela Ripon Effect' where these sets muted when she started to
talk. She had excessive high frequencies in her voice and the line to
Crystal Palce was good to 23kHz. Could this be something similar?
A TV that blows up when it sees Angela Rippon?
no, the sound muted when it heard her.
Now that would be a useful feature, especially if
there was a selectable menu e.g. David Cameron, Gordon
Ramsay, (add your own annoying celebrity)

David Cameron's a celebrity?
Cheesus. When did *that* happen?

That would be for future-proofing. He'll have to do
something after his party dump him. A natural for
day-time TV.

In article , Stefan
writes
I have a Sony crt about 15 years old which conked out whilst watching
freeview. Internal fuse o.k., but no on light comes on - dead.
Connected a Sharp 21"crt set - worked fine on analogue. Switch on freeview
and after a minute or so the set turns itself off ! sometimes to standby,
sometimes completely off !
Switch back on and with freeview turns itself off again.
Sat back and thought a moment. Wondered if freeview causes excessively high
voltages/current to tube. I reduced the contrast slightly and now it works
fine !
Could the freeview have blown the original Sony set ? If so how many crt
sets around are being blown by freeview boxes ?
Of course I could buy a new set, but cannot live with the poor quality of
lcd or plasma and crt sets now are scarce. Waiting to see if oled any
better.

Any thoughts on this strange phenomena from engineering types ?


How are you feeding the signal from the Freeview box to the TV. I have
one set (about 15years old) which appears to have an input impedance
much higher than 75ohm on its external video input. This set doesn't
have a Scart input, so I use the composite output from the Freeview box
to connect to the TV. This results in a very bright image from the
Freeview box (or anything connected to that input, such as DVDs or VCRs)
with a lot of saturated whites. After running like this for a few
minutes, the TV would shut-down.

The "solution" was to wire a 100ohm resistor across the input to achieve
the right input impedance. Now the image on Freeview is the same
brightness and contrast as the analogue signals and the set runs
indefinitely without shutting down. It was successive approximation to
get the right resistor value. My first impression was that the input
wasn't terminated at all, but a 75ohm resistor made the image too dark,
so I then tried 150ohm, before finally settling on 100ohm.

On a CRT set too high a video level will result in excessive currents
internally. There should be limiting circuits to prevent this and the
Sharp, like my old Solara, simply switches off when it senses it is
overheating due to excessive currents. If the Sony had no such
protection or was faulty then it could burn out some internal
components.

So the answer to your question is: yes, it is possible for the video
signal from a Freeview box to damage a TV, but only if there are one or
more latent faults with the TV to begin with.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)

In article
.co.uk.invalid,
Alan Pemberton wrote:
I have a Fergie portable that has a high-impedance video input.

I have a Pace Ondodgibox that feeds out distorted syncs unless
terminated in 75R.

I have a Fergie portable that uses the detection of valid sync pulses to
switch from rf to video input.

I have a Fergie portable that does not work with a Pace Ondodgibox.

I've also got a weird Fergie portable. Bought from Thames TV - they bought
them for IIRC one of the Olympics as cheap monitors and disposed of them
afterwards. RGB input on a DIN. TTL levels. Must be about 20 years old.
Still works as well as ever. Which isn't saying much.

--
*I love cats...they taste just like chicken.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Dave Plowman (News) wrote:
In article
.co.uk.invalid,
Alan Pemberton wrote:
I have a Fergie portable that has a high-impedance video input.

I have a Pace Ondodgibox that feeds out distorted syncs unless
terminated in 75R.

I have a Fergie portable that uses the detection of valid sync pulses to
switch from rf to video input.

I have a Fergie portable that does not work with a Pace Ondodgibox.

I've also got a weird Fergie portable. Bought from Thames TV - they bought
them for IIRC one of the Olympics as cheap monitors and disposed of them
afterwards. RGB input on a DIN. TTL levels. Must be about 20 years old.
Still works as well as ever. Which isn't saying much.

I had a similar one. Someone at BBC Dover Transmitter Team base sold kits
to do this. Other people may have done something similar. ISTR that the
set had the necessary switching chip to handle teletext and the unused
input was used for the TTL input.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11