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Did anyone else try this with a old CRT set?


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Old 10-03-2011, 19:10
Mike_1101
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This relates to a very old set that was scrapped many years ago and would probably be considered highly dangerous today.

My parents bought their first tv in the mid 1950s, made by "Ekco", it was bulky and heavy, but built like a tank and soldiered on for many years into the BBC2 era (a channel it was never designed to receive)

Around 1971 it developed a fault on the CRT that really needed the tube replacing but by this time that would not have made sense. Basically no picture appeared when the set was switched on. Instead the engineer showed them a trick that involved removing the cover over the rear of the tube and gently tapping the glass just in front of the electrical connections to it. Dangerous but it brought the picture back on many occasions, but as the tube heater was already glowing, what had gone wong with it?

A few months later my father found a second hand tv dealer who had a suitable spare tube that had been re-built. It was made by a company called either Goldstar or Goldseal. The old set carried on with the re-built tube until 1976 at which point it failed again and was beyond repair. They also had a colour set by then so it went to the tip.
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Old 10-03-2011, 19:19
Chromatron
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This relates to a very old set that was scrapped many years ago and would probably be considered highly dangerous today.

My parents bought their first tv in the mid 1950s, made by "Ekco", it was bulky and heavy, but built like a tank and soldiered on for many years into the BBC2 era (a channel it was never designed to receive)

Around 1971 it developed a fault on the CRT that really needed the tube replacing but by this time that would not have made sense. Basically no picture appeared when the set was switched on. Instead the engineer showed them a trick that involved removing the cover over the rear of the tube and gently tapping the glass just in front of the electrical connections to it. Dangerous but it brought the picture back on many occasions, but as the tube heater was already glowing, what had gone wong with it?

A few months later my father found a second hand tv dealer who had a suitable spare tube that had been re-built. It was made by a company called either Goldstar or Goldseal. The old set carried on with the re-built tube until 1976 at which point it failed again and was beyond repair. They also had a colour set by then so it went to the tip.
Probably an intermittent heater-cathode short..........
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Old 11-03-2011, 08:30
roddydogs
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BBC 2 was only ever on 625 lines, so how did a 1950s set recieve this? or did you mean it didnt?
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Old 11-03-2011, 08:56
Nigel Goodwin
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As suggested by Chromatron, it was a standard technique for CRT's with heater cathode shorts, often you could temporarily 'cure' it by knocking the short off.
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Old 11-03-2011, 13:55
AidanLunn
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BBC 2 was only ever on 625 lines, so how did a 1950s set recieve this? or did you mean it didnt?
There were dual standard sets out there, which were both 405 and 625 But they were way after the mid-50s.

I do believe a few early cable TV companies downgraded BBC-2 to 405 lines so that their customers could get it and they could deliver it without doing a major upgrade of their cable TV grid.
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Old 11-03-2011, 15:32
Nigel Goodwin
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I do believe a few early cable TV companies downgraded BBC-2 to 405 lines so that their customers could get it and they could deliver it without doing a major upgrade of their cable TV grid.
That sounds unlikely - much more probable (and what we did) was down-convert from UHF to VHF, been 405 or 625 makes no difference to the relay system, just the frequency.

Converting to 405 would have been EXTREMELY expensive, and serve no use.

Because 625 line channels are wider, you didn't use 1, 2, 3 etc. - in fact we used channels A, D and H for three 625 line colour channels, along with channel 4 and channel 8 on 405.
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Old 11-03-2011, 18:47
Mike_1101
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BBC 2 was only ever on 625 lines, so how did a 1950s set recieve this? or did you mean it didnt?
Sorry for any confusion, it was 405 only and we were well aware at the time that there was no way it could receive BBC2.

It did have a very basic FM radio facility though.
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Old 11-03-2011, 19:28
Pemblechook
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Anyone try turning a colour CRT upside down? The colours change.
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Old 11-03-2011, 19:29
Nigel Goodwin
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Anyone try turning a colour CRT upside down? The colours change.
It doesn't if it's not turned on, and it's stone cold.

The reason it changes is because you're rotating it through the earths magnetic field, and it deforms the showdowmask.

Just like moving a magnet near it.
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Old 11-03-2011, 20:10
Mike_1101
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It doesn't if it's not turned on, and it's stone cold.

The reason it changes is because you're rotating it through the earths magnetic field, and it deforms the showdowmask.

Just like moving a magnet near it.
I remember hearing about something called "de-gaussing", did it make much of an improvement?

I never saw it being done though.
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Old 11-03-2011, 20:23
AidanLunn
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I remember hearing about something called "de-gaussing", did it make much of an improvement?

I never saw it being done though.
I did the turning upside down experiment with a late 90s Toshiba portable.

The colours did change but they returned to their normal colours when I tuned it upright again. i believe this is because the Eath's magnetic force is strong enough to bend the shadowmask inside, but when you turn it back upright, the magnetic force of the Earth bends it back into its correct shape, with probably a very minor difference between "before" and "after", but a difference so small it's not likely to be noticed.

There are several ways of de-gaussing TVs, a few examples include using de-gaussing wands (my de-gaussing tool), a de-gaussing ring (reserved, I believe for situations where a degaussing wand would be too weak to de-gauss a magnetized tube), and even putting CRT TVs face to face, and switching one on to degauss the other (which is off).

The charge put through the thermistor ring around the face of the tube to discharge any magnetic forces from that TVs shadowmask is also strong enough to do what is considered to be a good enough job on a TV placed directly face to face with the degaussing TV.
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Old 11-03-2011, 21:39
Pemblechook
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It is the vertical component which sends the electron beam sideways due to magnetising of the shadow mask (whatever it is caleed in a PIL tube). The phosphors are side by side in a PIL tube. A magenetic field deflects a current at right angles to it. It must be the vertical component as the colours dont change when the set is orientated to face N or S or whatever.
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Old 12-03-2011, 00:02
AidanLunn
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It is the vertical component which sends the electron beam sideways due to magnetising of the shadow mask (whatever it is caleed in a PIL tube). The phosphors are side by side in a PIL tube. A magnetic field deflects a current at right angles to it. It must be the vertical component as the colours dont change when the set is orientated to face N or S or whatever.
You mean the line output or the scan coils?

My Toshiba did change its colours when I placed it on its back as well, screen facing up.
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Old 12-03-2011, 00:10
Pemblechook
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Eh?

Maybe I should have put 'Earth's magnetic field'.

The aperture grille in fact. Which having a vertical structure can only be magnetised vertically.
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Old 12-03-2011, 09:08
Nigel Goodwin
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I remember hearing about something called "de-gaussing", did it make much of an improvement?

I never saw it being done though.
I've done it thousands of times, and of course it compeltely cures the purity errors caused by the magnetised shadowmask.

It's why rotating a cold TV while turned off has no effect, as TV's deguass automatically at power on (it's what makes the 'thump' at switch on).
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Old 12-03-2011, 09:47
Mike_1101
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Just out of interest, did many people ask for replacement CRTs in old sets? The reason my father did this was that he did not like many of the programmes my mother liked and wanted a second set and that was in the days when there were only 3 channels.

I suppose there must have been enough demand if there were companies selling re-conditioned tubes.
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Old 12-03-2011, 11:09
Nigel Goodwin
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Just out of interest, did many people ask for replacement CRTs in old sets?.
We used to fit relatively small numbers of CRT's, and even keep common tubes in stock - most were either for rental sets, sets on insurance, or for refurbishing sets for resale.

Only very small numbers were ever done as chargeable jobs.

I did once fit a CRT in a customers house, as a 'private job', it was a 17 ich Ferguson 8000 - delta tube, full purity and convergence setup required

It takes you back!!
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Old 12-03-2011, 21:19
Superwomble
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Just out of interest, did many people ask for replacement CRTs in old sets? The reason my father did this was that he did not like many of the programmes my mother liked and wanted a second set and that was in the days when there were only 3 channels.

I suppose there must have been enough demand if there were companies selling re-conditioned tubes.
I think the high cost of TV's until the mid 60s made it viable to replace a tube instead of a TV, that is until foreign imports began to arrive in the late 60s, which began to bring down the price.

When colour arrived the design and complexity of a set made replacing tubes much less attractive, and the pace of improvements and reliability meant that by the time a set had done it's five year average life, the new sets were much better than the old ones so people preferred to replace the whole TV than refurbish the old one.
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Old 12-03-2011, 21:48
ney
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Our first TV as a was a Colour TV in the early 70s after mum and dad got married and moved into the house we are still in the now. A year or two before I was born and was a rented tv from the old Radio Rentals shops and was £10 a week. It had an old style light brown cabanet with a sliding door and every 14 to 18months something would go wrong with it and we had to phone the guy to come out and fix it.
Got rid of that in 1982 when we upgraded to a Decacolour tv with 8 channel tuner out of Comet and this was the first time we had a tv with a remote control. TV cost just over £170 at the time and that was a 20inch CRT. Dad did once take of the back of that tv and gave it a hoover and it seemed to work again after that.
Had that tv just unde 9 years before it started to play up and by then we needed a tv that had a scart at the back witch this tv had not. So in the late 80s we upgraded tv again.
Most TVs we have had have been 5 or 6 years old before we have replaced then apart from our frist tv.
Never had a teletext tv or a vcr untill the mid to late 80s.

Darren
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Old 13-03-2011, 09:24
janet owen
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Sorry for any confusion, it was 405 only and we were well aware at the time that there was no way it could receive BBC2.

It did have a very basic FM radio facility though.
Did you have the box attached to get ITV. we had an echo
in the late 50s then bought the box to get Granada ,as the set only had one tuner for home moss

If I recall my old man used to take off the front glass to clean the tube which got filthy, it was a 12 inch model.

JO
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Old 13-03-2011, 09:28
janet owen
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Our first TV as a was a Colour TV in the early 70s after mum and dad got married and moved into the house we are still in the now. A year or two before I was born and was a rented tv from the old Radio Rentals shops and was £10 a week. It had an old style light brown cabanet with a sliding door and every 14 to 18months something would go wrong with it and we had to phone the guy to come out and fix it.
Got rid of that in 1982 when we upgraded to a Decacolour tv with 8 channel tuner out of Comet and this was the first time we had a tv with a remote control. TV cost just over £170 at the time and that was a 20inch CRT. Dad did once take of the back of that tv and gave it a hoover and it seemed to work again after that.
Had that tv just unde 9 years before it started to play up and by then we needed a tv that had a scart at the back witch this tv had not. So in the late 80s we upgraded tv again.
Most TVs we have had have been 5 or 6 years old before we have replaced then apart from our frist tv.
Never had a teletext tv or a vcr untill the mid to late 80s.

Darren
£10 a week? rental, that's a lot.#

JO
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Old 13-03-2011, 10:37
Stewie_C
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Just out of interest, did many people ask for replacement CRTs in old sets? The reason my father did this was that he did not like many of the programmes my mother liked and wanted a second set and that was in the days when there were only 3 channels.

I suppose there must have been enough demand if there were companies selling re-conditioned tubes.
Don't remember ever doing any chargeable ones, but I was forever changing tubes in Decca Bradfords. We had loads on rental and maintainance contracts and way back then people were a lot keener to have stuff fixed because of the cost of buying new, or upping the cost of the rental.
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Old 13-03-2011, 11:44
neo_wales
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£10 a week? rental, that's a lot.#

JO
I was thinking that, £1 yes, £10 a week no.
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Old 15-03-2011, 19:43
ianradioian
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My Mum rented a colour set in 1976 , it was secondhand rentals, dual standard 19", I think it was £7 a month, a not inconsiderable sum then. I used to put it onto vhf from uhf sometimes ( with a thump sound and loss of picture) and listen to the line whistle!
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Old 16-03-2011, 01:02
jos
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I was thinking that, £1 yes, £10 a week no.
We had a rented B&W when we got married 1962 it was 5/- a week. (Five shillings)
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