helping a friend out with his new project. nice looking ctc 25 with a danish modern cabinet. looks like a new crt-25xp22 sylvania.set plays,however,it has sound until the agc and sync tube warms.sound goes and screen is a dark raster.removing the 6ka8 restores sound and there is some video,very x ray like.set has had some work done to it-shabby to say the least!any ideas?i have a nightmare with my frankenset-ctc16xl converted to 25ap22.tuner is out of a later model -spliced wiring,many resistore are soldered over the old ones and lots of "repairs?".so brutal,i want to throw it out.but it is rca.i cant let it go at least until i have exhausted all my energy to get it going!

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all tubes check good and operate properly in another set.agc adjustment does nothing.found a bad resistor in the video circuit and replaced to no avail.no sound or video unless that 6ka8 is out of the socket.

I have seen lots of cases of bad connections/bad solder joints in RCA's along with burned wiring...usually results in power supply voltages getting removed from a stage causing trouble. I'd check all the power supply voltage outputs and then check voltages at the tube sockets....sometimes heat from a tube causes cracking at the socket pins and it can be hard to detect the problem.