The Family DuMont

[CaryLee]

Originally Posted by earlyfilm

Cary, if it were me, I'd also purchase one of the $1.25 10 watt 200 ohm resistors that Nebr Surplus has and add it on to one end of the pot. Yes, I know the new pot is within 20% of the original, but that pot and the focus coil are in a divider network in your power supply. I suspect that with both the new pot and that resistor in place your B+ supply voltages will be better behaved, and this could possibly improve your weak reception.

Jas

Thank you for the suggestion. I went ahead and ordered two rheostats and two resistors so I'd have a spare set. Does it matter which side of the pot I put the resistor on?

According to the tracking number, the package from Surplus Sales is on schedule to arrive tomorrow. I'm looking forward to install!

[earlyfilm]

Originally Posted by CaryLee

Does it matter which side of the pot I put the resistor on?

Whichever side puts the best focus nearest to the center of the pot.

With the non-open pot in the bleader circuit, it will shift some of the various "B" voltages and you may have to tweak some of the adjustments, including the ion trap.

J.

[CaryLee]

Originally Posted by earlyfilm

Whichever side puts the best focus nearest to the center of the pot.

With the non-open pot in the bleader circuit, it will shift some of the various "B" voltages and you may have to tweak some of the adjustments, including the ion trap.

J.

Well, I had a 50/50 chance of getting the extra 200 ohm resistor on the "right" side of the focus pot...and I got it wrong. Best focus is now with adjustment turned all the way to the left. Pulled chassis to move 200 ohm resistor to other side of pot.

I did get a MUCH better picture, though. Eye Tube still very dim. Think it's a bad tube, since I could see faint action looking directly at tube.

As far as the picture goes, a lot of "ghosting", and the top of the screen bends right..I think...I've been looking at the screen in a mirror as I make adjustments out back.

Gonna move resistor and try again. Don't think it's going to change picture quality much, if at all. l

[M3-SRT8]

As far as the Dumont tuning tube is concerned, you will notice that there is a resistor installed at the back of the socket. These are frequently bad, and need replacing.

[CaryLee]

Originally Posted by M3-SRT8

As far as the Dumont tuning tube is concerned, you will notice that there is a resistor installed at the back of the socket. These are frequently bad, and need replacing.

Thanks!

[CaryLee]

Got the new focus control yesterday, and like Phil said earlier, the shaft is a tad longer, and needs the flat filed into it. A little work with the Dremel tool and it was ready to go.

These controls from Surplus Sales of Nebraska were packaged in 1960! Talk about NOS! I almost hated to open up something that was sealed in it's package when Dwight Eisenhower was President.

[CaryLee]

In the interim I had also cut new glass for the dial window to replace the broken one.

I've read references to both plastic and glass being used for the dial window. It looks like mine had some extra "fingers" soldered on to hold thicker glass than what was originally in it. Don't know the history of that modification, but apparently it was for standard 1/8 inch window glass, because that is what fit.

Does anyone know if the brass trim around the dial window is solid brass? It's not magnetic, so I think it is. There's a bit of pitting on the bottom near the tuner knob..probably from fingers touching it. I'm wondering how much polishing it can take. I don't want to polish brass plating off if that's all there is.