Quote:
Originally posted by gonzothegreat
Well, the filaments in the rest of the set light up so unless there are two filament circuits, that's OK. That leaves the B+ circuit. I'll take a look at what tubes it uses. I know I have a tube tester around here. There is also an old black paper covered cap that might be suspect.
Thanks for the component ID! Now where can I get a replacement or two since I'll probably blow one or two before it gets better?
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You might try Radio Shack--they might have a few fusible resistors left in their inventory (although they are very scarce these days, as today's TVs don't use them). Failing that, I'd ask around at TV repair shops that have been in business awhile (long enough to have serviced tube-type TVs); they may have a few of these beasts lying around.
Since I responded to your post, I've been thinking about the HV problem in your RCA New Vista TV and have come up with some suggestions. You mentioned a "capped" tube in the HV cage near the flyback. In a black-and-white set this is the HV rectifier (and the only tube, period, in the cage); the cap is the plate connection, IIRC. If this is a color set, you will have two tubes in the HV cage with caps on them; one is the HV rectifier, as before, while the other will be the HV regulator (6BK4; the HV rectifier is usually a 3A3, though a couple other types were used by different manufacturers). If you have no HV, one or both of these tubes may be defective (or dead altogether); a dead HV rectifier always kills the raster, as will defective horizontal oscillator, output or damper tubes or defective components in these circuits. If the flyback is running excessively warm, or so hot the wax is melting, it might be defective (shorted).
Keep in mind that if the horizontal oscillator is far off frequency, it can kill the raster as well. However, be careful: In tube-type TVs with power transformers, it is possible to burn out the transformer if the horizontal oscillator is running too slow or not at all. The reason is that the horizontal output stage's plate current is regulated by grid-leak bias, obtained from the horizontal oscillator circuit. If there is no bias on the control grid, the current rises to the point where it overloads the power transformer. If the power supply is not fused, the transformer will go up in smoke from the heavy current overload. This is why it is never advisable to operate a TV set, black-and-white or color, with the horizontal-oscillator tube out of the circuit, or if the tube or circuit is defective.
Again, I hope this information helps. The RCA New Vista sets, which used 6CW4/6DS4 Nuvistor (aka acorn) tubes as RF amplifiers, were very good ones with excellent pictures, and seemed to be built well; I remember seeing a few such sets when I was in grade school in the 1960s. Our school had a fleet of these, operating from a master antenna system, and they all had great pictures on the PBS (then called NET for Natl. Educational TV) channel in Cleveland.
Good luck and very kind regards,