1950s or '60s vintage Zenith TVs, Need some info

[vortalexfan]

Originally Posted by Kevin Kuehn

Most DMM have an input resistance of at least 1meg, so using your DMM would not significantly change the voltage reading from what Sams got using a VTVM. There are however notes on the Sams schematic stating the control settings they used when making measurements. That's because some voltages can vary with different control settings.

Your 5AQ5 680 ohm cathode resistor is not out far enough to cause a serious bias issue. But you do need a known good tube in there to move forward. I would think your 6AQ5 would work, if it is in fact a good one.

What perplexes me is how you seem to enjoy back paddling. Last we heard you said the funky negative voltages went away when you temporarily removed C50(.01uf). It was suggested that you remove that cap to correct the negative voltage situation. Have you done so, or replaced it with a know good cap? And if so what was the outcome? Now you're right back to wondering willy-nilly without a clue or sense of direction. I'm trying to provide you a sense of guidance, but like they say you can lead a horse to water, but..

Well my comments are due to the fact that it seems that my comments have upset certain folks on here and because of that I was trying to take their feelings into account (read notimetolose on post #239) and because of that I didn't want to have to read through anymore rant posts from people who were upset at how I was going about troubleshooting this TV (notimetolose's exact words were that I was making no sense and that I was being a smartass and that I have no idea what I'm doing when it comes to using test equipment which is not true.)

So that's why I'm trying to be more careful with my comments.

Anyways the reason why I went down the cathode bias resistor route was because you kept on referring to the fact that the Audio Output tube in this TV is Cathode-Biased (Self-Biasing) and so I was trying to look into that aspect of the circuit as to why my audio circuit wasn't working right and the voltages were not right.

So yet again it seems that I misread the situation when it came to reading your comments and what you were suggesting that I look into.

I was noticing that you like to throw out subtle clues in your posts when it comes to helping people troubleshoot circuit issues (sort of a way of telling a person what the issue is without actually telling them what it is outright so that they can figure it out on their own.)
I first noticed that when you were helping me with that Meck TV when I was having the issues with the dead short in the B+ circuit in that TV, you told me in a subtle manner to double check the polarity of the filter caps for the B+ circuitry (the big ones that were installed under the chassis originally that had the electrical tape around them) and at first when I looked at how they were installed they seemed correct in how they were installed but then one of the caps vented on me and then I looked at it again and I realized that I had the caps installed positive to positive and negative when it needed to be positive to negative in that situation and when I installed it correctly it was fine, but I wouldn't of figured it out without those subtle hints.