Tube brighteners.

[Graham G3ZVT]

Split from this thread:-

https://www.vintage-radio.net/forum/...d.php?t=162082

Originally Posted by usradcoll1

It's been ages since I used one. In a few sets the HV rectifier punctured through the insulation, as stated before. I told the customer that it was the cheaper way to go. I carried a few of them with me. both kinds.
Dave, USradcoll 1. I quit servicing 30 years ago, except my own equipment.

I find it fascinating to learn about the differences in what passes for normal on each side of the pond.

For example watching shango066's channel on Youtube it's surprising how many "brighteners" were deployed. The concept was not unknown here, although we just called them CRT heater (filament) isolation transformers to the best of my recollection, and you could work out your full career without ever encountering one.

When they were used, it was more to do with eliminating severe hum due to heater/cathode leakage, than overrunning the heaters. I wonder if others agree with my assessment?

[joebog1]

Brighteners in Australia were used when the cathode had died sufficiently that the screen was quite dim. When we fitted a brightener ( that's what we called them) we advised the customer to start saving for a new tube, a regunned tube or a new TV. The "real slick" brighteners had taps that could be upped as the emission got lower and lower. We didn't have "heater cathode" shorts!!! We had a piece of figure 8 flex soldered to the heater and cathode pin of a spare tube socket. we started the set and connected one lead to chassis and the other lead was tapped a few times onto the topcap of the 6CM5 or 6DQ6 booster valve. Watching carefully we did this untill the sparkler effect stopped inside the tube. Thereafter there were no shorts. . DONT laugh!!! this was highly effective.

Joe

[Argus25]

Originally Posted by rambo1152

For example watching shango066's channel on Youtube it's surprising how many "brighteners" were deployed.

Brighteners were very popular in the USA and most TV service people had boxes of them. All of the ones I have cut open for inspection contained an autotransformer, they were never about isolating the heater, just over-running it to get higher electron emission from the failing cathode, and trying to put off the inevitable tube re-gun or replacement.Most American sets used 6.3V heater supply from the transformer.

It was possible to make a very compact "brightener" transformer for the task aided by:

1) Autotransformer design
2) High permeability core
3) 60 Hz operating frequency.

So they could just fit in a small extension base on the CRT that was roughly about the same diameter and not too long.

Possibly why these might have been less common in the UK, many of the sets were AC/DC series heater chain types, making it more awkward.

[lesmw0sec]

Two methods here - one is the transformer to boost the heater voltage, giving a bit more emission from the cathode, the other which Joebog1 lists, is zapping the cathode surface with a high voltage in order to break up the cathode coating and (hopefully) get a bit more emission that way. I've used both methods many years ago with varying degrees of success, but the high voltage zap was of course cheaper and a lot more fun!

[Andrew B]

I have never seen one of the brightners, too young at 61, but when colour tubes started to fade we had a device the powered up the heaters +10% and then pulsed G1 and each of the RGB cathodes in turn. I think it applied +120V DC to G1 for a very short time, stripping off tired cathode material, seemed to work for a decent time afterwards.

[AC/HL]

There used to be adverts in Television for a device, "Cathodray", or similar from memory. It fitted inline with the tube socket. Presumably just an autotransformer.

[ms660]

Boosting or blasting the CRT on a full time use telly was a bit like rearranging the deck chairs on the Titanic.

Lawrence.

[G6Tanuki]

A CRT heater-booster would often be enough to get another year's life out of a weak tube; remember that back in the 50s and 60s a new tube (or a new telly) would have been a significant cash-cost to your average viewer.

Wasn't a tube-booster one of Clive Sinclair's first products?

EDIT: Photo attached, from July 1961 Practical Wireless. Is this _the_ Clive Sinclair or someone else called Sinclair?

[Reelman]

When we were married in 1981 all we could afford was an old Philips B/W TV because it was free. It had a very dim picture so I used my old H&M train transformer to run the tube heaters rather bright for a few seconds and that did the trick, disconnected from the heater chain of course. I successfully repeated the procedure once more before we bought a second hand colour set. When we did I put the old Philips in the loft and to my shame left it there when we moved along with a KB and another. 32 years on I often think about going back to our old house in Coventry and asking if I could reclaim them........

I’ve certainly got one of the RS tube boost transformers with the percentage taps hidden away, it came from my father-in-law’s radio and TV shop.

Peter

[MotorBikeLes]

I never used one myself, but I came across more than one on Finlandia colour sets. I forget which make of CRT they had, but it was a common retro fix I believe. It MAY have been because the stock heater supply was low rather than the tube itself. These were simple mains transformers with 6.3V and + 20% as I recall.
Les.

[short wave]

If memory serves me " R - S" used to do them

[ionburn]

Wasn't it the case that late model tubes were not very successfully boosted due to the limited cathode material?

[G6Tanuki]

Yes, RS used to do the heater transformers with the normal 6.3V and an additional tap that gave 6.3 +20% as a boost. These were surprisingly cheap and I found them ideal for powering small '9V' DC power-supplies, the boosted 6.3V, when bridge-rectified using silicon diodes (OA202 etc) gave about 10V on-load, great for feeding stuff that normally devoured PP9 batteries.

[TowerRadio]

I have a RS 4 volt CRT booster transformer,I can certainly remember my father getting a bit more life out of a Bush TV tube with one of these boosters,possibly made by Elstone. Les

[Nuvistor]

A little more information on the Sinclair booster.

[Welsh Anorak]

That unit (post #8) looks interesting, especially as it doesn't have any power supply! I suspect it's used to lift the heaters from chassis to 'cure' a H/K leak. Can't see how it could increase the heater voltage._Edit: crossed with the above post, which says it boosts the heater voltage. I wonder how?

The Thorn 3000 series TVs had an extra 20% tap on the mains transformer. I don't think this was supposed to be used for increasing the CRT's heater voltage but it did work.

Of course the transformer was the proper way to do it. More common was the extra dropper resistor (or worse) hung onto the CRT's heater pin.

[G6Tanuki]

I suspect that the cylindrical body-part of the Sinclair booster contained an autotransformer.

[Argus25]

Originally Posted by Welsh Anorak

Can't see how it could increase the heater voltage._Edit: crossed with the above post, which says it boosts the heater voltage. I wonder how?

I explained in post #3 that these brightener units contain autotransformers, it is no mystery how they work. You will note though they won't work for sets that are powered from DC, that scenario practically never happened in the USA where the brighteners were super popular and part of every TV serviceman's kit.

[Craig Sawyers]

Originally Posted by G6Tanuki

A CRT heater-booster would often be enough to get another year's life out of a weak tube; remember that back in the 50s and 60s a new tube (or a new telly) would have been a significant cash-cost to your average viewer.

Wasn't a tube-booster one of Clive Sinclair's first products?

EDIT: Photo attached, from July 1961 Practical Wireless. Is this _the_ Clive Sinclair or someone else called Sinclair?

Uncle Clive would have been 21 in 1961, so it is unlikely (but not impossible) to be one of his products. Although his father had a machine tools business in London, so the booster could have been one of his products,

Craig

[Argus25]

Originally Posted by Craig Sawyers

Uncle Clive would have been 21 in 1961, so it is unlikely (but not impossible) to be one of his products.

Craig

Not unlikely at all, the autotransformer booster at this point in history was 10 year old American technology and if he was well traveled "Uncle Clive" would have seen these on trips to America along with many other TV and Audio innovations. In those days it took about 10 years for new tech to get from the USA to the UK and about 15 to 20 years to get to the Antipodes.