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In my ill gotten youth working in a TV shop, I had charge of disposing of the old sets and CRT's...
I would take them out the back and lop the guns of the CRT's off with a hammer.--Not safe, but strangely satisfying--for a teenager!
Thinking back, wish I had saved some of the more rare CRT's and sets now.....
I used to dissect the various guns from the tubes, and noticed the Sony types always had Really Tiny cathodes. --Ive seen bigger pinheads!
They are/were only around 1-1.5mm in diameter, while the other sets delta gun tubes like A56-120X, (A development of Mullard under-licence from RCA--guess there is a 560xxx22 equivalent over in USA), and Mono tubes had much more robust looking cathodes--About 2.5mm diameter for most of them, and looked 'solid' in comparison, to the feeble tiny Sony CRT parts.
Always reckoned that this was the cause of the 'unboostability' we found in UK using the old 'Bulb-Bopper'--Even the B-K wouldn't do them--Always ended in disaster.
(A 15W pygmy bulb wired in series with cathode, grid and 240V mains. It also had some switches and a 6.5V-8V transformer)
The tiny Sony cathodes were literally torn apart by the heavy arcing and currents the 15W bulb allowed to pass--Lit this is around 60mA, More with a cold bulb. No wonder all the sparking occured!
I'm guessing the same old process of slow ageing over the years must be causing the sony tubes to go low, just like them all, no different really apart from the size, so tried the above as an alternative--Nothing to lose on a stuffed CRT!
I notice probably every CRT booster has an increase heater option while boosting, maybe with some very low CRT's this is essential to get things started...
Just go in small stages till you get some current flowing and make sure there's no arcing going on!
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