This was a technical history study subject of mine, it wasn't to do with the TV sets themselves per se, it was a study on the effects of asymmetric loading of the power grid, but it did throw up some interesting historical development details on the TV sets themselves.
Not all the UK TV production was transformerless, there were notable exceptions. (Example: 1957 PYE PTV, which were based on a studio monitor, apparently excellent sets, it needed good isolation as it had a metal cabinet!)
Early, just pre and post 2nd world war CRT sets had transformers as it was the prevailing design choice at the time and often had mains derived CRT final anode HT... absolutely lethal.
Later solid state colour sets nearly all had some form of switching supplies/phase angle thyristor regulation or similar, often non isolating. Exceptions were a few quirky hybrid sets that were very power consumptive, notable was the 1960s Philips G6 chassis, that in 22 and 26" screen varieties consumed 400W: they also used shunt stabilisation of the EHT which was a radiation hazard to any foolhardy engineers that ran them without the sweep/line stage screening box in place.
The late fifties to early seventies monochrome sets did mostly use transformerless techniques and achieved the necessary dropping of power for the tube/valve heaters with series resistive droppers in combination with series diodes to limit dissipation.
A few sets even used lossless capacitive droppers for the heater chains.
A whole range of tubes/valves were produced in Europe specifically for use in these sets and were designated 'P' range by the European manufacturers, these had heaters that were for use in 300mA series strings, had suitably increased heater cathode insulation, and were characterised for the relatively low plate/anode voltages provided by the ½ wave mains rectification.
The reasons the system was adopted was purely cost, it being very much cheaper to make ceramic resistive droppers than transformers, they were no where near as expensive as transformers to produce, and factors lighter, though that was coincidental considering the weight of the glass CRT. Virtually none of these sets would run on DC mains, (diode droppers don't work on DC, the tube/valve heaters would be overrun for starters).
I fail to understand why transformers were so expensive in the UK, with their then large Electronics industry.
The weight issue is a "red herring" as the power transformer for a normal 23" Australian TV set can be held in one hand.
OK, you know you are holding something, but it isn't a significant contributor to the overall weight of the set.
Not all of the sets sold in Aus were transformer PS types, notably European designed imports often weren't. I don't think there was ever any regulation introduced that they should be isolated supplies, it was just a sensible risk adversity on the part of Australian manufacturers, perhaps only of benefit to service techs.
Of course, in operation in customers homes, the extra safety of a transformer PS set was then arguably not applicable.
I was in the Electronics workforce from mid 1959, & although I never worked as a TV Serviceman on domestic BW TVs, saw enough of them to have a fairly wide experience of what circuitry was used, & as I said above, the only transformerless TVs I saw were the old Admiral portables.
I have no memory during that time of
any "European designed" imports on the market.
The unique Australian TV channel structure would have discouraged any European maker from selling sets in this country, at that time the UK were making 405 line sets which were totally non-compatible, & if they made a 625 line set would be more likely to try to sell it in Europe.
One exception was Ekco, who unsuccessfully linked up with Oz firm AEI to build & sell both TVs & AM Broadcasts Radios in the Australian market,during that brief foray adopting the local standard transformer-type architecture in both cases.
There were a few "private imports" which Techs took it upon themselves to modify, but it wasn't a viable proposition in most cases.
As to safety, transformer type TVs did not require the expensive & complex insulation measures needed with "hot chassis" sets, so were safer for both the user & Serviceman.
In the case of a resistive dropper if it is overloaded it will just go open circuit, a lot of sets in-fact had droppers that had fuseable spring links. Almost any old TV tech., will tell you that replacement dropper resistors were the bread and butter of their living.
Transformers when overloaded can of course catch fire, particularly the ones fitted in veteran sets, where the windings were often potted in wax or bitumen.
Wax or bitumen potting was not used in Australia, & about the worst you could expect from a failed transformer was a lot of smoke & some stink.
The HV secondaries were the usual culprits in a cooked transformer, rather than the primary.
Transformers commonly lasted decades.
My personal choice would perhaps be the transformer set being the safest overall but I don't think such a study was ever done, in service reliability being a completely separate matter entirely.
Regards,
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