Dumont RA113 "Burlingame" restoration
 

A few weeks ago Phil Nelson put me in touch with the owner of this nice Dumont RA113. He and his brother grew up with this set and he really wanted to get it restored to working condition.

Although I've plenty of other projects, I agree to take a break from them and work on it. They pulled up in front of my place with it yesterday afternoon.

I removed the chassis while it was out on the curb to lighten the load but the cabinet was still quite heavy.

The set had been kept inside it's whole life and is in very good condition. The finish looks very similar to my blonde Sentinel so it's probably also made from Korina wood. As best they can remember it is working when retired from service.

There's a ding on both cabinet sides from the door handles whacking into them. Seems they should have used a little bumper like on Zenith portholes.
http://farm4.staticflickr.com/3797/9...b34f7df2_z.jpg http://farm6.staticflickr.com/5522/9...7dfd6a7c_z.jpg http://farm4.staticflickr.com/3743/9...17290f7d_z.jpg

The CRT had been replaced with a Westinghouse 17BP4B back in the late 50s and the set saw very little use afterwards. Even so I was surprised at how quickly it showed emissions well into the good with excellent cutoff and rock solid life test.
http://farm6.staticflickr.com/5522/9...f34d9d48_z.jpg http://farm3.staticflickr.com/2887/9...f35d739d_z.jpg

The tube chart shows a 17AP4. The back does not have a cutout for the CRT but luckily the 17BP4 just fits.
http://farm4.staticflickr.com/3673/9...088ba450_c.jpg

The chassis is rust free and quite clean :)
http://farm8.staticflickr.com/7426/9...047d182b_z.jpg http://farm6.staticflickr.com/5486/9...db52e69b_z.jpg http://farm8.staticflickr.com/7426/9...b2b88ba5_z.jpg

I see a few replaced caps but it's mostly original.
http://farm4.staticflickr.com/3803/9...6bd90905_c.jpg

It also appears that a HV anode lead has been spliced it. Perhaps the original 17AP4 had a different type of HV cap ?
http://farm3.staticflickr.com/2825/9...b6d1dbc1_z.jpg

I love seeing other RA-113's!

This one is a pretty example.

I've had to hold off on the restoration of my mahogany DuMont for now, but will be getting back on it during the winter, when I don't like going outside very much. I had to find a power transformer for mine, but thanks to a great internet friend, it was located, so that major hurdle was overcome.

I look forward to seeing progress on this set as it is brought back to life, :thmbsp:

Hi Bob,

Very nice find! It looks exactly like the one I'm beginning to restore. I, too thought it was a "Burlingame" but I now believe that it is a blond version of the "Revere." Mine is model number RA-113-B4. I'm just in the process of putting together a cap order. (It's the one I picked up in Kenosha last month for $55.) Here are a few photos:
http://i1216.photobucket.com/albums/...ps95b190b3.jpg
http://i1216.photobucket.com/albums/...pseb25fc2b.jpg
http://i1216.photobucket.com/albums/...ps083b149c.jpg

My CRT is the original DuMont 17AP4 which tests good. Should be a fun restore. Good luck!

-Clark

Right you are. I didn't notice the difference in legs when I looked at the models on Phil's website.

It's not my set though - I'm restoring it for someone. I did consider going for the set you got but it's much too big for my place. The sooner I get this done and out of here the better :yes:

I wouldn't have guessed it beforehand, but that cabinet's attractive in blonde.

I think the RA-113 is an interesting & fun set to restore -- enjoy!

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

Very nice sets. I have a much rougher one around here some place I've been working on. Will be fun to watch you guys restore these :)

17AP4 was a metal cone wasn't it ? if so that would explain the splice because you would have to change the anode to fit a 17BP4

mike

The anode connection on the 17AP4 looks the same. Mine has a quick disconnect inline with the anode lead (as does Phil's). It looks like that was removed on that set. You can see one end of it hanging in this photo. And the 17AP4 is an all glass CRT:
http://i1216.photobucket.com/albums/...ps517ab038.jpg

I noticed that the focus control on mine looks pretty bad (green corrosion on the element wire). I haven't tested it, but I preemptively ordered the same replacement Phil used from Surplus Sales of Nebraska since I know these are a common failure point.
http://i1216.photobucket.com/albums/...ps32c7026a.jpg

I hear ya, these suckers are big. I'm not quire sure where I'll put mine yet :scratch2:

I'm very fortunate to be restoring a set that now two masters, Phil and Bob, are blazing the trail!

-Clark

Those are some very nice blondes! Usually the finish is all beat to heck on the blonde stuff.

I think it's because they used an actual light hardwoord rather than "limed oak" type finish.

I finally have the chassis up on the workbench. First I'm going to pull the 5U4 rectifier and power it up to make sure the power transformer is OK.
http://farm8.staticflickr.com/7444/1...c7739705_c.jpg

http://farm3.staticflickr.com/2891/1...139e457b_c.jpg

Do you guys think this ASC 1,000 pF, 10kV cap is a suitable replacement for the original 500p HV caps ?
http://farm6.staticflickr.com/5535/1...c6286de1_c.jpg

it might work , I used 470pf caps from moyer that were 10kv or 15kv that are round in similar applications and they worked.

mike

When most rebuilders got a 17AP4 dud, they would rebuild it as a 17BP4 or, if they could aluminize, as a 17BP4B, since as these newer types were more marketable and used the same bulb.

Since the maximum external coating capacitor on a 17AP4 was 500 µµF greater than on the replacement 17BP4, you are still within factory specs on the HV to ground capacity in the CRT circuit. This is the capacitor that you sometimes hear warnings not to increase due to the potential shock hazard.

Increasing the other two 500 µµF 10KV capacitors to 1000 µµF would allow the second HV rectifier to operate more efficiently, but the tiny HV increase and extra loading on the HV output tube and Flyback should be minimal.

I'm impressed by how beautiful the insides of that set is!

Jas.

Thanks for the info. I'm also considering using some ceramic HV caps as they are a lot less expensive.

The power transformer is good and the tuning eye is showing signs of life :)
I get some HV with the old caps still installed, but it's definitely less than it should be. I expect new caps will take care of that.
http://farm4.staticflickr.com/3703/1...42924ef3_c.jpg

Making steady progress with the recap. Those old caps are very sticky and gooey :yuck:
http://farm8.staticflickr.com/7323/1...b6bb817e_c.jpg

The caps in mine were all gooey, too. I had to use Boraxo to get the gunk off my fingers :sigh:

Looking good, Bob. I'm curious to see how the ceramic caps work in the HV doubler.

-Clark

Thanks. The ceramic caps and a few others parts I needed arrive tomorrow. With a bit of luck I'll try firing it up later that night or on Saturday.

Crap! I just missed the Fedex guy and he left a tag saying another attempt would be made on Monday :( I've been using Fedex for years they've always left the package somewhere on the property if no one answered the door.

Bummer. Maybe it's a new driver. Here in Madison, they give you the option of picking up the package after 5:00 PM on the day of the attempted delivery. I live only 4 miles from their depot, so I have done that on occasion. But in Chicago, it's probably way out in the burbs somewhere.

I finally took a closer look at the tag and realized the depot was only a couple miles away and open to 9:30pm on a Friday night so I got my parts after all :)

Here are the 500pF, 15kV ceramic caps I'm going to try.
http://farm8.staticflickr.com/7316/1...16b7399c_c.jpg

Cool. I have a feeling they'll work just fine in this application.

Are those the Vishay Cera-Mite 615R Series? If so their data sheet lists them for TV and Monitor applications. Nice to know someone is still looking out for us. :thmbsp:

East Paterson changed their name to Elmwood Park a few years ago. That town is about 10 miles from my mom's.
http://farm4.staticflickr.com/3673/9...088ba450_c.jpg
Paterson NJ is a real dive, so this town didn't want that association anymore...:thumbsdn:

They sure are :yes:

I'm not sure what to do about this resistor. It's R268 and is in series with the 6BG6 HOT grid. The schematic and parts list show 100 ohms but this is a 47 and appears to be original. When I measure it, I get 98 ohms.

It seems to me that if it really is twice what it should be, it could reduce the 6BG6 drive and flyback output. Should I leave it alone since it's close to the 100 specified in the service info, or replace it with a new 47 ?

http://farm6.staticflickr.com/5474/1...c8115098_c.jpg

My chassis has a 100 ohm in there(looks original), so apparently yours should be fine. Sams schematic shows a 47 ohm(with see note). Note 6 on parts list says some models use 100 ohm. :) I think it's purpose is to damp out parasitic oscillations, so it's probably not super critical on value. You see those used on audio outputs too.

During my 21CT55 restoration I found that SAMs showed the production changes of later sets than the RCA schematic showed, so the 100 ohm may have been a production change in later sets. I guess you need to decide if you want to restore it to original condition or incorporate the production changes. Is that 47 ohm resistor discolored, like it has been getting way too hot? That would explain why it measures high. If so, I would replace it with another 47 ohm resistor of higher wattage.

Dave

No, it's not discolored - just dirty. I guess I'll leave it alone and see how it plays.

Here's another head scratcher. This section of the candohm resistor R282 B measures about 5300 but the schematic shows 2140. I've seen plenty of candohms go open but not drift in value that much.

Perhaps it's another production change ? What does the Sams show ?
http://farm3.staticflickr.com/2824/1...d55ee1bb_c.jpg

Sams says 2140. You're measuring out of circuit?

Nuts, I guess I'll have to bypass it. Yes, I measured it out of circuit.

Scratch that - I didn't fully take it out of the circuit after all. Now I get 322K so it's probably corroded or partially burned out inside. There's no wattage specified in Riders but I suppose 25W should be good enough.

Sams lists each section at 10 watts.

Thanks. I figure I should replace both sections while I'm at it. I think 1500 and 2200 should be close enough to the original 1480 and 2140.

I managed to get the yoke and FC off so I can try it out on the workbench with a test CRT. There's clearly a weld where it was rebuilt and the yoke was reluctant to slide over that portion of the neck. Some slow careful rotating back and forth did the trick.
http://farm4.staticflickr.com/3724/1...b5a1d88c_c.jpg

Good, I'm glad you were able to get the yoke off. I'm not going to mess with mine until the 17AP4 gets tired, which will probably be years from now.

BTW, that 25K resistor in the horizontal output was toast on mine, too. I also initially mistook it for a paper cap.

Looking forward to seeing you fire it up on the bench with a test CRT!

-Clark

I would change the resistor! It already changed value and will progressively get worse.
I see some Allen-Bradley five percent resistors used. :scratch2:

OK, I'll put a good 47 in there. Are you referring to the 5% resistors in the upper-right ? I guess Dumont used better quality parts than their competitors. I'm finding very few that need replacing :)

Some of the Admirals, of the time were using German and Japanese resistors, connected in parallel and series, to get the proper values needed.
The German resistors had the flat leads.
I read somewhere that there was a parts shortage during the Korean war. :scratch2:

I've worked on a couple early 50s Admirals with resistors like that.

I took a closer look at the anode lead and discovered two splices with a piece of line cord between and the rubber cap is falling apart! That's all going to be replaced :yes:
http://farm8.staticflickr.com/7434/1...07355634_c.jpg

Whooah! And 3M Gasket cement used in place of Corona Dope!

Back in the day, before air-conditioning, we used to see a lot of this from shade tree mechanics who tried to stop arcing on the anode connector due to high humidity. Usually, it took a razor blade to scrape off the mess and doing that destroyed the connector in the process.

Jas.

I dove inside the HV box last night and found more evidence of old repairs.

All three HV caps had been replaced. They used "pigtails" with pointy leads sticking out rather than plunging the ends into the solder cups. Not the proper way to dress HV connections :no:
http://farm4.staticflickr.com/3716/1...a520f164_c.jpg

One of the 2.2 ohm filament resistors had cracked so I replaced them both.
http://farm8.staticflickr.com/7454/1...ed59e67a_c.jpg

More evidence of past HV troubles.
I think this Micamold cap is 0.001 mfd @ 500v and the white dot indicates it's really paper inside so I'm going to replace it.
http://farm4.staticflickr.com/3666/1...ef1c655c_c.jpg

Oops, I didn't replace that cap in mine, I thought it was a silver mica. I'll make a note to replace it the next time I pull the chassis.

I also chose not to pigtail the HV caps. Getting the solder to pool just right in the cups was a bit of challenge, though. I found it best to orient the chassis so that the solder cup I was working on was horizontal, otherwise gravity causes too much of the solder to spill out.

Looks like you're getting close to the first power-up.

There's still a chance it is. I'm going to test and dissect it to see what's really in there.

I flipped the chassis upside down to get the first one to pool properly.