Quote:
Originally Posted by Kevin Kuehn
Also, leaving the 1 meg carbon comp resistor going to the CRT anode button original is asking for trouble. Only after you change it will you know if it's contributing to your voltage sag.
Tuner voltage issue - Looking at Sams schematic the tuner gets it's b+ from the voltage derived on the cathode(pin 8) of the 6V6 audio output tube(V12). A starting point would be to measure V12 pin 8 relative to ground, then R13 feeds that voltage to the tuners RF amp, mixer, and oscillator. So verify that you have the same voltage on one side of R13 as you do on pin 8 of V12. Next measure on the opposite side of R13 and see how much lower the b+ is at that point. Then from that point forward, R10 splits off b+ to the mixer tube( one half of V2) and R12 feeds b+ to the oscillator(the other half of V2). So measuring on both sides of those 3 resistors(all referenced to ground) should give some indication of where you're dropping too much b+ to the tuner.
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I just noticed R13 is under the main chassis(near the tuner), but R10 and R12 are inside the tuner, so would require removing the tuner cover to measure. If you get lucky, and actually the most likely is the problem will show up right around R13. According to your earlier voltage measurements there's not much drop in voltage between the 6AK5 and 6J6.
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I just measured the Voltage from Pin 8 of the 6V6 in reference to Chassis Ground and I got 158.4 VDC and then on the input side of R13 I got 158.4 VDC as well, and then on the output side of R13 I got 154.4 VDC so only a 4 VDC drop between Pin 8 of the 6V6 tube and R13's output side.
I already have the cover removed on the tuner so I just need to figure out which resistors in the tuner are R10 and R12, so I can measure them.