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#18
07-10-2009, 07:56 AM
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Lot of questions in there! Let me try to answer:
Replacing caps piece meal was my first thought, but I got some advice in the forum to go ahead and recap the whole thing. Its neither here nor there -- The set showed no signs of life before recapping, even though the electrolytics weren't totally shot. 1) No Reverse Polarity electrolytics 2)Yes, it seems unlikely there is a short on B+ with 475V. In fact w/ 355V center tap on the 5u4, the peak open circuit voltage is only 500ish. So there's very little drop going on. Im not sure what went in the 5u4, i'll check tonight. 3)The CRT base connector on this set has 2 pins which do nothing but connect the filter choke to the rectifier when the connector is inserted. Ie. if you do nothing, the power supply is completely disconnected downstream of the rectifier. 4)Tube TV -- I'm a little confused -- the 5V winding for the 5u4 filament IS the b+ winding. Maybe I mis-interpreted what you're asking. In any case, with everything else disconnected, all the transformer windigns show isolation. 5)I'll try to bring the set up w/ a pair of diodes and a variac. However, since the diodes will drop much less voltage than the 5u4, i'll have to keep the line voltage low. This will also lower the 6.3V filament taps. Need I be concerned? Solid state switch mode power supplies are my main game, so I'm still getting used to the tube side of things... I'll poke around some this weekend and see what I can see. Alex 
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