The Family DuMont

[CaryLee]

Originally Posted by Kevin Kuehn

Lookin' good. I used to could see up close at a microscopic level back in my 20's, now I need to rely on a couple different strengths of reading glasses that I pick up at the grocery store.

Thanks! It's not as tidy as if I'd restuffed the cans and cardboard tubes, but there's a lot of room under that chassis for a lot of stuff.

I've been wearing specs since I was about 10 or earlier, but I used to be able to focus close up still wearing them. Over the last few years, that ability has just about disappeared. I've always been heavily "near sighted". Now, with my glasses on, I can see clearly from about a foot away to out as far out as I want, but things get blurry close up. I take my glasses off, and I can see crystal clear from about two inches out to about 6 inches out. There's an area between the 6 inch and one foot mark where I can't see ANYTHING clearly, with or without glasses, and that's where bifocals would come in.. call it vanity, but I'm resisting "old people glasses" as long as I possibly can!

[David Roper]

Heh, I hear that. When I finally assented to trifocals I went home from the examination and found a letter in the mail from AARP.

fml

[dieseljeep]

Originally Posted by CaryLee

Thanks! It's not as tidy as if I'd restuffed the cans and cardboard tubes, but there's a lot of room under that chassis for a lot of stuff.

I've been wearing specs since I was about 10 or earlier, but I used to be able to focus close up still wearing them. Over the last few years, that ability has just about disappeared. I've always been heavily "near sighted". Now, with my glasses on, I can see clearly from about a foot away to out as far out as I want, but things get blurry close up. I take my glasses off, and I can see crystal clear from about two inches out to about 6 inches out. There's an area between the 6 inch and one foot mark where I can't see ANYTHING clearly, with or without glasses, and that's where bifocals would come in.. call it vanity, but I'm resisting "old people glasses" as long as I possibly can!

I went with blended tri-focals.
I had the old style lined bi-focals, as safety glasses, years ago. They were nasty for night driving. It's bad enough, that you have to wear glasses. You might as well get glasses you don't mind wearing.

[CaryLee]

Finished up the recap job this eve, replacing the three 10000 volt caps in the HV section.

Reassembled, and powered up..no fire...no smoke..no buzz...no tubes glowing..no nothing....

Totally dead.

Did a bit of tracing of the power circuit through the on/off switch..and wouldn't it be a bummer if the set has been dead since around 1960 due to a bad power switch?

Well..the power switch IS bad. I jumped it and everything lit up on the bench. Still no explosions, no fire, no smoke, etc. But every tube lit up as it should.

Anyone have any luck repairing a power switch? If not, any idea where to get replacements? The switch is a combination on/off switch-volume control and hold control. I can solder in a temporary toggle switch for testing purposes.

I've posted a "Want Ad" with part numbers in the "Classifieds" section.

[dieseljeep]

Originally Posted by CaryLee

Finished up the recap job this eve, replacing the three 10000 volt caps in the HV section.

Reassembled, and powered up..no fire...no smoke..no buzz...no tubes glowing..no nothing....

Totally dead.

Did a bit of tracing of the power circuit through the on/off switch..and wouldn't it be a bummer if the set has been dead since around 1960 due to a bad power switch?

Well..the power switch IS bad. I jumped it and everything lit up on the bench. Still no explosions, no fire, no smoke, etc. But every tube lit up as it should.

Anyone have any luck repairing a power switch? If not, any idea where to get replacements? The switch is a combination on/off switch-volume control and hold control. I can solder in a temporary toggle switch for testing purposes.

I've posted a "Want Ad" with part numbers in the "Classifieds" section.

First, you have to determine what make of control it is. CTS, seems to be the most common. It could be Mallory, Clarostat, IRC or another East coast manufacturer.
Then, take the control all apart and transplant a known good switch.
One of the posters on this forum, could make up a control. IIRC, you sent them the defective control and they would repair or duplicate it.

[CaryLee]

Originally Posted by dieseljeep

First, you have to determine what make of control it is. CTS, seems to be the most common. It could be Mallory, Clarostat, IRC or another East coast manufacturer.
Then, take the control all apart and transplant a known good switch.
One of the posters on this forum, could make up a control. IIRC, you sent them the defective control and they would repair or duplicate it.

The one that is in there is marked "Centralab". I don't have any spares of any kind, so I'm going to have to locate a complete replacement. I would guess that an IRC switch won't fit on a Centralab control?

[dieseljeep]

Originally Posted by CaryLee

The one that is in there is marked "Centralab". I don't have any spares of any kind, so I'm going to have to locate a complete replacement. I would guess that an IRC switch won't fit on a Centralab control?

How could I forget "Centralab". They were on the Northeast side of Milwaukee.
I don't even think a CRL replacement switch would work. OEM and replacement parts, even from the same manufacturer, didn't interchange.
I'm only going by memory, as it's been ages.

[CaryLee]

Originally Posted by dieseljeep

How could I forget "Centralab". They were on the Northeast side of Milwaukee.
I don't even think a CRL replacement switch would work. OEM and replacement parts, even from the same manufacturer, didn't interchange.
I'm only going by memory, as it's been ages.

The SAMS photofact lists a "Concentrikit" by IRC, and lists a bunch of individual part numbers for individual components of the switch. Amazing how folks used to be able to repair stuff on that level!

I might try taking the switch apart and seeing if I can shoot some contact cleaner in there. It still "clicks" as if it's turning one and off...but apparently no internal contact. Don't have anything to lose since it doesn't work now.

[Kevin Kuehn]

I've found switches where the contacts are stuck open simply from setting too long and hardened grease. Sometimes a squirt of tuner cleaner/lube into the switch and cycling several times will free things up. One the other hand the contacts may be badly burned, in which case you'll need a replacement switch.

Edit - just seen you're already on the right track in you last post.

[CaryLee]

O.K., no luck trying to get the on/off switch to work, so I soldered in a jumper and am working the set off a switched power strip.

I remember saying early on that if I didn't get a TV out of this DuMont, at least I'd have a heck of a big old mono FM radio...and that's what I've got so far!

I'm wondering though, since I've never seen this set do anything (including play FM radio, so I have made progress), exactly how is it supposed to act?

It has a three-position switch which switches from FM to TELEVISION to PHONO.

I'm getting FM radio on both the FM and TELEVISION settings, and when I switch to PHONO, the sound kicks off. On PHONO, I can plug in a phono cord and get a buzz if I touch the center conductor on the other end of the phono cord, so that seems to be working (I must have SOMETHING around here I can plug into that jack! Man, has technology changed! Curse you Optical Audio and HDMI!). On all settings, the heater filament in the picture tube glows. At no time, on any setting, does it sound like the picture tube is firing up..no static electricity sound, etc. No noise from the HV section.

I get a VERY dim eye tube, barely see it, but there is some action there while tuning through FM if I look close enough. Could be a wore out eye tube.

It appears I have a balky FOCUS control. When I turn that control, there is a "dead" spot in the middle where the sound drops out, but it picks up at either end, far left or far right. What the FOCUS has to do with that I have no idea at present.

My first though is that the FM/TELEVISION/PHONO switch isn't working correctly. Should I be getting FM sound on either TV or FM settings? Should the picture tube heater be lit at all times, on all settings? I would assume that switching to FM, the picture tube should shut off, but is that handled through the HV section alone?

Thank you for any thoughts/advice.

[earlyfilm]

Cary, I believe you said this is your first TV, correct?

I also understand that you have neither substitute tubes, nor a tube checker, correct?

Next step is to dim your lights and verify that the plates on the 5U4 rectifier, the 6BG6 Horizontal Output, and the 6W4 Damper are not getting pink as this indicates something is badly wrong.

If any plates are glowing, turn the set off immediately.

Since you have not replaced any resistors, I assume that a resistance check will not be productive at the moment.

I cannot call the Sam's part numbers as the only schematic of the RA-112 is the Riders one at ETF which uses the factory numbers.

http://www.earlytelevision.org/tv_sc..._diagrams.html

However, I'm going to suggest that you measure all the resistance reading listed in Sam's from tube sockets, with the set unplugged. This will give practice for the next step and it might spot a pre-existing problem.

Make a Xerox of the two pages of Sam's and write down the resistance, at each point and color marking the ones that are off by more than 20%.

If no tube plates were getting too hot, your next step is to check the voltages that are shown in Sam's voltage chart.

Follow the same procedure of writing them down, again marking those 20% off in a different color.

James

[bandersen]

Yes, you will get FM reception in both FM and TV positions and the CRT filament is lit at all times.
The only thing that happens in FM mode is that the CRT brightness is cut off. All the TV circuits are still running including the high voltage.
So you really are wearing out the TV tubes and CRT while just listening to the radio.

[earlyfilm]

Originally Posted by CaryLee

It appears I have a balky FOCUS control. When I turn that control, there is a "dead" spot in the middle where the sound drops out, but it picks up at either end, far left or far right. What the FOCUS has to do with that I have no idea at present.

Check your schematic. Your B+ is fed through your wiper on the focus pot. I assume that is a wire wound. You might see if it is open in the center as that could be causing part of your problems.

Originally Posted by CaryLee

. . . . . (I must have SOMETHING around here I can plug into that jack! Man, has technology changed! Curse you Optical Audio and HDMI!).

I would be cautious about plugging in anything that uses transistors or chips into the record player jack, because this set has a semi-hot chassis though a 100 K resistor. Not enough to current there to hurt a person, but it might be terminal to a transistor circuit that was not buffered against a little AC.

James

[dieseljeep]

Originally Posted by bandersen

Yes, you will get FM reception in both FM and TV positions and the CRT filament is lit at all times.
The only thing that happens in FM mode is that the CRT brightness is cut off. All the TV circuits are still running including the high voltage.
So you really are wearing out the TV tubes and CRT while just listening to the radio.

I have a 15" RA103 or 104. It has the regular Dumont chassis, with the inputuner and FM radio. It also has a record changer and a AM radio chassis.
The strange part is the phono audio goes through the TV chassis. The radio is only used for AM radio reception. It's a six tube job, with a tuned RF stage.
Both chassis have a SE 6V6, output stage. The selector switch on the radio, cuts off the power to the TV chassis and switches the speaker to the radio chassis, when it's being used for AM reception.
I, personally, would have used the radio chassis for record reproduction.

[CaryLee]

Hey guys! Lookee what I found!