A Lemon set?

[Don Lindsly]

The yoke should be snug against the CRT in a B&W set.

[Einar72]

I don't wanna go too far out on a limb having not seen the schematic, but there may not be enough performance engineered into the poor old thing to not have some buzz. I think it was Zenith that had a pot somewhere in their design called a "buzz control". The usual cause of buzz on white-intensive video (like text) is the strong white-level signal "spilling over" into the sound circuit. I wouldn't expect the poor little Muntz's AGC circuit to handle the overmodulated video signal from a modern VCR/DVD/Cable Box/NTSC Converter modulator, try an attenuator on the antenna input, since there's no more need to have weak-signal capability...

[radio nut]

Originally Posted by miniman82

Audio buzz can be cured with an alignment or a slight tweak to a coil or two in the IF strip, but you really have to be familiar with the set to go poking around without a scope. If slightly adjusting fine tuning cures the buzz but jacks up the picture, you need an alignment.

This set does not have a fine tuning adjustment........high end ! Huh?

[AdamAnt316]

Originally Posted by radio nut

This set does not have a fine tuning adjustment........high end ! Huh?

Oh, it was "high end", all right. Madman Muntz was legendary for getting rid of 'superfluous' features such as fine tuning and AFC in the sets he sold, stripping them down to their absolute bare essentials. It is said that he carried a pair of insulated wire cutters with him, and would start snipping components out of a running TV until it stopped working, then have his engineers put the last snipped part back in. They don't call it "Muntzing" for nothing.
-Adam

[dieseljeep]

Originally Posted by Einar72

I don't wanna go too far out on a limb having not seen the schematic, but there may not be enough performance engineered into the poor old thing to not have some buzz. I think it was Zenith that had a pot somewhere in their design called a "buzz control". The usual cause of buzz on white-intensive video (like text) is the strong white-level signal "spilling over" into the sound circuit. I wouldn't expect the poor little Muntz's AGC circuit to handle the overmodulated video signal from a modern VCR/DVD/Cable Box/NTSC Converter modulator, try an attenuator on the antenna input, since there's no more need to have weak-signal capability...

Zenith sets had a buzz control because of the type of audio detector circuit they used.
You're right regarding, attenuating the signal. Muntz didn't use much of a AGC circuit. They seemed to run the IF and RF "wide open".
You also had to try several different 12AT7's and 6BL7's to get those circuits to work properly.

[radio nut]

What does having the volume all the way up have to do with the sound buzz disappearing?

[radio nut]

Well, got curious and checked voltages on the 6t8 audio detector tube...
pins 1-2 -3 should be minus.5 minus 1.8 and minus .5 respectively.....they check 20 volts pos. at least on those pins with a digital volt meter. with analog the needle moves off the scale to the left even with the neg lead or pos lead to ground......
now I am confused...

[Don Lindsly]

The reference voltages were likely taken without an antenna. The voltages you are seeing are normal.

[radio nut]

Well I took the diagram to an expert because something just did not look right but I could not put my finger on it.

He looked at it and said the ratio detector tube is isolated from voltage and should be signal only. He stated that the ratio detector transformer was probably shorted.
I called Moyer's.,....got a new one.....put it in and sure enough it works and there is only Macrovision buzz that goes in and out in conjunction with the lines on the screen that likewise come and go.
I can't wait to try a tape/disc that is not encoded with Macrovision!
I tore the old transformer apart and there was a dark brown spot on the side where it looked to be arcing.