#16
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Of course you should use an isolation transformer when you service such a set on the bench.
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#17
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Well, usually Soviet sets had a transformer, but my vintage one is an exception: it haves autotransformer, not transformer, so there is the risk of live chassie; and the thing only works at 127 or 220 V - is not the model that also works at 110 V (I have an 220 V - 110 V transformer at my home). The Romanian "Electronica" Naţional V.S. 43-614 that I intend in the future to get me, haves no transformer, but works at 110 V or 220 V, so I can use the transformer that I have.
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#18
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As Telecolor said, 99% of European sets made before the early 80s, both B/W and color, tube or SS, had a live chassis.
This is not only due to the cost, bulk and weight of a 200 or 300 watt magnetically shielded transformer which was simply too big to fit inside the cramped cabinet of most European tabletop sets. Live chassis was also very popular in Europe due to our 220v line voltage, so you just need a rectifier to get your 280v b+ in the US you have 110v and so you need some kind of voltage doubler if you want to make a live chassis set, that's probably quite complex and also unreliable, also US sets, even tabletops, are A LOT larger than european sets, they almost always have 90 degree CRTs while most larger European sets have shallow 110 degree CRTs 110 degree CRTs also need a horrible amount of power for their deflection and convergence circuits, a typical mid 70s solid state color set (a philips K9) with a 110 degree delta gun CRT slurps about 250 watts. AFAIK the first european sets to use an isolated SM power supply were late 70s color Telefunkens, most other makers followed shortly afterwards, Philips was the last to join the isolated SMPS trend in about 1983 with their system4 chassis. Also during the 80s as the power consumption of the average set dropped under 100 watts and the room inside TV cabinets increased due to smaller chassis, there were quite a few newly designed sets fitted with a power transformer. Mivar, Nordmende and Thomson used a power transformer, Philips instead used an 1:1 isolation transformer to be able to fit AV inputs to some of their older live chassis designs like the K12 and K30-K35 |
#19
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The live chassies sets had another demn problem too: they neded readjusment after every electricty fluctuation... the tv's with transformer where more rezistent to electricty flucatution. So, from this point of wiew the Soviet sets where the best (and the safest!).
Is true that "R.C.A." manufactured live chassie television cameras?! |
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