Console stereos: 1958-84

[rinso]

After I replaced the capacitors and installed a polarized plug, I had no hum at all. The wiring in my 9301s did not take the center tap of the balance pot to ground, for some reason. Anyway, I have zero hum and I even used a scope to verify.

 

[phillymatt53]

After I replaced the capacitors and installed a polarized plug, I had no hum at all. The wiring in my 9301s did not take the center tap of the balance pot to ground, for some reason. Anyway, I have zero hum and I even used a scope to verify.

You've got me a bit confused there, I assume you are talking about the HUM balance pot.
You say that the balance pot wiper doesn't go to ground - THAT would be of course EITHER the HUM balance, AND the input level balance.

Regardless of whether there's hum or not, this is my answer....
The HUM balance pot wiper DOES go to a 100 ohm cathode bias resistor which IS grounded, and as I mentioned, keeps those cathodes and the filaments NEAR ground potential, which is what Magnavox did on purpose.
The reasoning, if you can understand it is - it's to prevent the input and output tubes from any "flashover" or arcing issues inside the tubes from happening, along with raising the filaments above ground potential for the 6EU7's.
A lot of people (mainly amateurs/hobbyists/internet guru's) don't fully understand this type of design or why it is a necessary thing to do with tube amplification.
Magnavox didn't just put it in there for looks.

 

[rinso]

You've got me a bit confused there, I assume you are talking about the HUM balance pot.
You say that the balance pot wiper doesn't go to ground - THAT would be of course EITHER the HUM balance, AND the input level balance.

Regardless of whether there's hum or not, this is my answer....
The HUM balance pot wiper DOES go to a 100 ohm cathode bias resistor which IS grounded, and as I mentioned, keeps those cathodes and the filaments NEAR ground potential, which is what Magnavox did on purpose.
The reasoning, if you can understand it is - it's to prevent the input and output tubes from any "flashover" or arcing issues inside the tubes from happening, along with raising the filaments above ground potential for the 6EU7's.
A lot of people (mainly amateurs/hobbyists/internet guru's) don't fully understand this type of design or why it is a necessary thing to do with tube amplification.
Magnavox didn't just put it in there for looks.

I assure you I am not an amateur, but my background is in mobile communications, so I do assume you are correct. But, I love fiddling around with stuff just to see what would happen. Now if I could only find a blank chassis or a place near me that does sandblasting, I would remove all the parts and rebuild, I'd also replace all the passive components I could. Since both my 9301's came from less than clean environments, (barn and landfill) I'd like to get them all spiffed up like I've seen others do.