The Family DuMont

[holmesuser01]

I'm having to crawl with the capacitor replacements on my RA-113 with the rectangular screen. BUT, every time I replace a few, I've noticed changes on the screen, and the sound.

I love all the room there is under the chassis on a DuMont.

[CaryLee]

Originally Posted by holmesuser01

I'm having to crawl with the capacitor replacements on my RA-113 with the rectangular screen. BUT, every time I replace a few, I've noticed changes on the screen, and the sound.

I love all the room there is under the chassis on a DuMont.

Happy to hear it's going well for you. That bolsters my confidence! The replacements for my missing tubes are starting to arrive. Got my capacitor order in today with "Just Radios", including the three 470pf 15kv caps that seem to be only available from him. I kicked around using high voltage ceramics, but figured ordering all my caps at once from Just Radios was a pretty good deal, including getting the HV caps that are guaranteed to work well. Also ordered the micas for the Horizontal output circuit, since it seems they are troublesome.

I was just joking with my wife that even if it turns out my picture tube is toast we should end up with a big ole' decent FM monaural radio!

[CaryLee]

Ordered my caps from JustRadios in Canada. I know they get pretty good reviews, but I'm not sure about dealing with Canada Mail. Just found out if I want a tracking number, it costs an extra $10, so after dealing with JustRadio's Microsoft EXCEL ordering system yesterday for quite a while yesterday before I got a file they could read, I just found out they pulled my order from shipping today waiting to see if I wanted to pay the extra $10 or not. I guess I got spoiled by Antique Electronic Supply's ordering system, which is pretty easy to deal with, and of course, tracking is free. Man, I REALLY wish we still had a LOCAL electronic supply store!

[ggregg]

I've ordered from Just Radios a few times and it's always been no problem. The problem with shipping doesn't really seem to lie with Canada Post but rather the US Customs service. Which is why the delay. Or so I've been told.

[David Roper]

John Folsom has a restored 30" Crosley.

[CaryLee]

Originally Posted by ggregg

I've ordered from Just Radios a few times and it's always been no problem. The problem with shipping doesn't really seem to lie with Canada Post but rather the US Customs service. Which is why the delay. Or so I've been told.

Good to hear. I haven't ordered anything out of Canada in recent memory. I usually skip Canadian EBAY auctions because shipping is so high.

I agree many problems seem to be on the United States side. I have a tube for a 1945 Minerva radio floating around out there somewhere. Shipped before Christmas from Pennsylvania, and last tracked leaving Lehigh Valley, PA Dec. 26th..and it disappeared from radar after that.

A tube for my DuMont project wasn't shipped until the 27th out of Wisconsin, and I got it yesterday.

Most of the problems we've had with mail lately were because of our local carrier, and a tracking number is nice, because it keeps them on their toes, particularly when they mark an item as "delivered", and it's not in my mailbox!

[CaryLee]

Still waiting for my capacitors to show up in the mail, but we've got the DuMont in the house and I noticed the speaker is going to need a "re-cone". I've never done that before. I've done a little searching on the internet and found companies that will do the recone, and that's definitely an option, but does anyone know of a good supplier for a recone kit or parts to do it? It's a Jensen P10 speaker.

Found some added info: The SAMS says a Quam 10A4A speaker is a factory speaker as well. I wouldn't be opposed to replacing the whole speaker if I knew a good equivalent substitute.

Thanks!

[Phil Nelson]

Does the speaker really need reconing, or does it just have a few holes or rips?

I have successfully patched speakers using tea bag paper and flexible glue. You can buy a special "service cement" made by GC but many people report success using flexible glue from a craft store. Some people even use coffee filter paper. Your TV's audio section is not a high-fidelity system; a patched speaker will sound just like the original.

Tea bag paper is so light that it will blend in pretty well with the speaker material. If that doesn't satisfy you, you could darken it with a magic marker but I would not paint the cone.

Just an idea . . .

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Phototone]

People lament the demise of local parts stores for small electronic parts, but I gotta tell you in general the local stores charged multiple times higher for the same capacitors and resistors you can get mail order, or internet order. We still have ONE local parts store that inventories capacitors and resistors (not Radio Shack), and their prices are high enough that I use them for emergencies only. And, they are a wholesale store.

[CaryLee]

Originally Posted by Phil Nelson

Does the speaker really need reconing, or does it just have a few holes or rips?

I have successfully patched speakers using tea bag paper and flexible glue. You can buy a special "service cement" made by GC but many people report success using flexible glue from a craft store. Some people even use coffee filter paper. Your TV's audio section is not a high-fidelity system; a patched speaker will sound just like the original.

Tea bag paper is so light that it will blend in pretty well with the speaker material. If that doesn't satisfy you, you could darken it with a magic marker but I would not paint the cone.

Just an idea . . .

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Howdy Phil!

Thanks for the idea on fixing the cone. I might be able to give the repairs a try, but I have a feeling it's toast. It's pretty crumbly. I noticed the speaker cloth on the front of the set bulging slightly and it's because there's chunks of speaker cone or foam resting in the bottom of the cone, against the cloth. Pressing lightly against he cloth, it's pretty "crunchy" sounding, and there are at least three places where the cone is cracked through right now. I'll have to pull the speaker to take a closer look. I might be able to get enough of a repair done that it will put out some kind of sound at least, when I get to that stage in the operation. There is certainly no hurry on the speaker, just want to line up a repair or replacement ahead of time while I'm stalled waiting for parts.

Thanks again!

[Electronic M]

If there is a foam ring that is supposed to bind the outer edge of the cone to the frame then I believe there are re-foam kits available.

EDIT: If it is truly toast measure the resistance of the voice coil and buy a speaker that has the same mounting dimensions and voice coil resistance if it is a PM type...If it is a field coil type then it gets more complicated.

[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.