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Replaced the last few off-spec resistors, including a 6.8 meg (R171 from the AGC line to +225V) that was completely open. Made a MAJOR difference. I think the video portion of the set is good to go at this point. The point about reduced performance vs the 630TS is a good one.
Pictures look great now, and with careful adjustment of height, centering, and linearity pots, I can get a nice, reasonably circular test pattern. Contrast range much improved now, and it makes a really nice picture. Will try with the 10BP4 this weekend. to see how it looks with the real tube in it.
Sound still WAY out of tuning range. Can barely start to hear it at one extreme of the fine tuning adjustment. I assume this is a simple oscillator slug adjustment? Not too familiar with split IF strips like this set has.
Am considering the addition of direct AV inputs so I can easily run this thing without need for a modulator. RCA described this for the 630TS chassis in an article in "Broadcast News", and the relevant circuitry looks pretty similar to the 721 chassis. Anyone done this and have any suggestions?
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