The Family DuMont

[Reece]

Different sizes of new cones are cheap. Cut away the old cone leaving about an inch of old cone still attached around circumference of the voice coil, glue in the new one. The ones sold below have foam surrounds which might cause a problem with "bottoming" of the voice coil on loud bass so it might be necessary to devise a way to stiffen the surround a bit.

http://www.electronix.com/advanced_s...r+cone&x=0&y=0

[CaryLee]

Howdy!

Thanks for all the great advice! Especially the stuff about the speaker. The supplier for the replacement cones is great!

Finally started working on the set in earnest. Here's a photo of the cabinet after the cleaning with GOJO, and treatment with Howards "Mahogany" finish restorer and several applications of Howards "Feed n' Wax". I didn't want to do a complete strip and refinish, but it looked pretty ugly and "dried out" before, so I didn't know what I was going to be able to "get away with". Turned out pretty presentable, I think, without losing it's "oldie" charm.

Interesting to me was finding my grandparent's telephone number from the 1950's, starting with the "TR" exchange, written on the cover to the HV section. (As in "TRinity5-2437") Put there to ID the set while in the repair shop, my guess. I remember when I was little my grandmother was on a party line, and the only reason she got a "private" line was because, over the years, everyone else on the party line got private numbers! She was the only one still on the party line for years, getting the cheaper rate, until sometime in the late 1970's the phone company discontinued party lines and started charging her for a private line.

I was worried that the tuner might have a stripped/broken gear, since the knob would turn about a third each way and then bind. I knew to never force it, but we've had kids in the house over the last 20 years, and THEY didn't always know not to force it. Good news was the only reason it was binding was because the string had broken and was stuck in the gear teeth in a couple spots, causing the bind. I'd read about the dreaded "fiber gear", but it looks like the gears in my tuner are all metal.

Everyone around here who's looked at the underside of the chassis has found it pretty intimidating. The biggest recap I've done is on an RCA 99K console radio (1938), and it turned out good. This appears to be about twice that, so if I think of it that way, it's not so scary looking!

[CaryLee]

Mystery Tube! That black metal tube center-left in first photo has all the numbers rubbed off..and the photos in the SAMS showed a small glass tube in that spot..6AH6 video amp tube.

Glad I got the "Production Changes Bulletin" with the old SAMS folder..it shows that tube was changed to a 6AC7 tube on chassis code "R" and later. If anyone needs the production changes bulletin, let me know and I can scan it and sent it to you.

There was a tube in the tuner that I thought was wrong too, and was ready to order the one shown on the parts list, then got to looking at the changes bulletin and saw that the "mixer tube", 6AK5 on the parts list, was changed TWICE during later production runs...first to a 6BC5, and then to a 6BC6...and the 6BC6 is what was in that spot. That's when I figured out that the letters stamped on the back of the chassis are "chassis codes" that coincide with production runs shown on the changes bulletin. Mine is stamped "AM", which coincides with the last change on the list. Seems to denote that my set is from the last production run, and has every single change made..now I'm going to have to look over my capacitor list and see if I ordered any wrong due to production changes! Live and learn!

Second photo is of tuner string squirrel's nest after I "unclogged" it from the gears..looking close, the middle gear on the shaft MIGHT be fiber! Glad it didn't get chewed up!

[old_coot88]

Cary,
I'm truly awed at this project, to be restoring such a rare heirloom handed down within one's own family.
Wonder how many here are old enuff to remember the dreaded fiber timing gear in the Model A Ford engine.

[wa2ise]

Originally Posted by CaryLee

Mystery Tube! That black metal tube center-left in first photo has all the numbers rubbed off..

You can usually find the tube number embossed in the metal part that surrounds the octal plug part of the tube.

[CaryLee]

Originally Posted by wa2ise

You can usually find the tube number embossed in the metal part that surrounds the octal plug part of the tube.

Thanks. I took a look but don't see any number there. It's a JAN military surplus tube, apparently Ken-Rad..Ken is visible, "Rad" is worn off. The only numbers on it are a "V4", and "SC961A", but I haven't found any cross-reference to that number. There is also a barely visible "2" like it's the end of the a number, and cross reference to a 6AC7 is an 1852, so that's a possibility. Visually, it does appear to be the correct 6AC7, and the heater pinouts match, so I'm going to figure that's what it is for now since I don't have any reason to think someone would have put the wrong one there. It's the only metal tube in the TV, and apparently the 6AC7 is only available as a metal tube. I've now seen photos of the embossed number like you mentioned, and this tube definitely doesn't have one.

[CaryLee]

Recapping has begun! No turning back now....

[David Roper]

Originally Posted by CaryLee

apparently the 6AC7 is only available as a metal tube

A vanishingly rare 6AC7GT was produced. There is at least one vendor selling them for a very reasonable price; it's tempting to get one or two for experimentation to see if they are at all suitable for use in TVs.

[ChuckA]

Originally Posted by CaryLee

Thanks. I took a look but don't see any number there. It's a JAN military surplus tube, apparently Ken-Rad..Ken is visible, "Rad" is worn off. The only numbers on it are a "V4", and "SC961A", but I haven't found any cross-reference to that number. There is also a barely visible "2" like it's the end of the a number, and cross reference to a 6AC7 is an 1852, so that's a possibility. Visually, it does appear to be the correct 6AC7, and the heater pinouts match, so I'm going to figure that's what it is for now since I don't have any reason to think someone would have put the wrong one there. It's the only metal tube in the TV, and apparently the 6AC7 is only available as a metal tube. I've now seen photos of the embossed number like you mentioned, and this tube definitely doesn't have one.

Military tube then the number missing is VT-112


Chuck

[CaryLee]

Originally Posted by ChuckA

Military tube then the number missing is VT-112


Chuck

a-HA! Thank you!