Hello all,
Well I've been at it again, building stuff!
This time around I built a CRT booster, based on a booster I used in my shop years ago. It is quite primitive and can be quite brutal, but it works really well on both triode and pentode CRTs.
It had to be built because a GEC telly I recently acquired for restoration had a tube as flat as a pancake, with virtually no emission. I've got to say thanks to Marc for picking up the telly, storing it and checking the CRT for me.... Cheers! ?
Anyway, it works by shoving about 250v across cathode and grid, via a 15W lamp and current meter. The voltage is reversible, which helps with the cleaning process once an initial plasma is produced. I've also put on a "Nuke It!" circuit that rapidly switches the polarity, for added boom!
There's a few pictures below. Circuit diagram to follow.
The inauguration proved to be a success, with my tube going from almost nil emission to pretty good, in about 5 minutes.
Anyway, pictures below....
Inside enclosure.
Component side of PCB (storyboard again!).
Track side of PCB.
PCB wired up and fitted.
Booster attached to CRT .
The Booster of Boing! in action 🙂
As you can see, the CRT got up to 90% of maximum FSD.
That's all for tonight.... Will get a diagram and instructions up in the next few days.
All the best,
Tony
Standards are like toothbrushes. Everybody needs them, but nobody want to use yours!
I like the 'Nuke it' feature! A sense of humour always helps the proceedings! As you say can be a bit brutal but if you have a tube as flat as a witches t*t you have nothing to lose......
Hi all,
I have to say that the "Booster of Boing" certainly surprised me at just how well it brought the GEC's tube back to life. I tested the tube using my Beamec CRT tester and despite allowing the tube to simmer for many many hours it remained as flat as the proverbial bought of wind only managing one or two increments of scale deflection. Tony then got to work with his nuclear attack device Booster and sure enough after a few minutes the tube was showing life. Putting the Beamec back onto the tube for a point of reference showed that it now had a reasonable chance of a picture with a scale deflection of a good half way.
Amazing results from what was a near dead CRT.
Marc
BVWS member
RSGB call sign 2E0VTN
That takes me back... a friend Andy had a similar thing, no case, just a bit of vero board , a G8 mains transformer, a G11 on off switch and a few leads with micro hooks on them... lethal!
He was the "don" of boosting the A51-231X ITT tubes to great effect... He'd hook this thing up, curse, repair it (it always had a wire or two hanging off) ... plug it in, and then turned off the workshop lights... He'd connect the heaters, and the cathode connection, switch it on, and tap the offending grid connection with the end of the hook, whilst watching the neck carefully. Every tap you'd get a flash, until there was a bigger flash. "That's it, don't do it again, or it'll go to nothing" ... and repeat with the other guns... they always came up like new and lasted! The B&K wouldn't touch them for some reason. The Murata thing would go great, and they'd be flat again within the hour....
... thankfully 'elf and safety never caught up with this lethal thing!
Hello all,
So here's the circuit diagram of "Fluffy"
Enjoy!
Standards are like toothbrushes. Everybody needs them, but nobody want to use yours!
That takes me back... a friend Andy had a similar thing, no case, just a bit of vero board , a G8 mains transformer, a G11 on off switch and a few leads with micro hooks on them... lethal!
The original shop booster was made by the owner, Jeff. Basically a small wooden board, an 8v bell transformer, a round dolly type light switch, a HT supply directly connected to the mains via a choc block, half of which was melted!
... thankfully 'elf and safety never caught up with this lethal thing!
Likewise.... They would have lined us up against the wall if they saw the original contraption!
Cheers Doz
Standards are like toothbrushes. Everybody needs them, but nobody want to use yours!
Hi all,
I have to say that the "Booster of Boing" certainly surprised me at just how well it brought the GEC's tube back to life. I tested the tube using my Beamec CRT tester and despite allowing the tube to simmer for many many hours it remained as flat as the proverbial bought of wind only managing one or two increments of scale deflection. Tony then got to work with his
nuclear attack deviceBooster and sure enough after a few minutes the tube was showing life. Putting the Beamec back onto the tube for a point of reference showed that it now had a reasonable chance of a picture with a scale deflection of a good half way.Amazing results from what was a near dead CRT.
Hi Marc,
The Nuke it! button wasn't even operational when I came over to yours ?
It's such a pity that the process wasn't videoed. All those sparks inside the tube and the lamp going bananas.... It never failed to impress the customers. They usually stood well back!
One of the things I remember with the booster I made in the shop was that one had to be careful to disconnect the cathodes after a bop, on certain tubes. What would happen is sometimes the tube would spark internally, which could spell trouble for the set. I had to do this with G11s, because any sparks would usually kill the TDA2600 frame o/p chip. TX10s had a habit of blowing video o/p transistors. The worst ones were the 9000s.... Anything could go in one of those, and the tubes usually didn't improve all that much in any event.
The best practice was to run the TV for about 5 minutes, with cathodes disconnected, maybe with some gentle tapping of the tube neck!
Tube boosting was such an organic thing in our shop ?
Cheers!
Standards are like toothbrushes. Everybody needs them, but nobody want to use yours!
