View Full Version : Dumont Ra-112 19"

01-13-2017, 10:50 AM
I just got a Dumont RA-112 last night and I've begun working on the frozen tuner. The little bolt on tuning shaft with gears is oiled and works very smoothly. The tuner utself is very tight and will only move and inch in each direction. I've tried oiling the front of the shaft by the gears with very little improvement. What am I missing here?

01-13-2017, 11:18 AM
Have you opened up the inductuner and flushed out the old, dried grease and relubed ?

Lots of good info and photos on Phil's site:

01-13-2017, 12:31 PM
I cleaned off excess old lube and added small amounts of oil to each joint. I used q-tips with contact cleaner on the coils and they're shiny.

01-13-2017, 02:24 PM
Keep cleaning and oiling. Pay attention to the gears and shafts.

Careful of oil dripping into circuitry below.:smoke:

01-13-2017, 03:31 PM
I've been cleaning and oiling it. I can now turn it it from one end to the other, but it's still stffl enough that it will round out the knob. Thank god the knob is more nylon and not Bakelite. I guess I'll just keep at it....

01-13-2017, 03:46 PM
I suggest carefully spraying with electrical parts degreaser down in to the grease and bearings to flush out all the last traces of old grease.

01-13-2017, 05:35 PM
Thanks guys. After much cleaning,lubricating the tuner and working it back and forth, it's finally working smoothly. Now I've got to see if I can remember how to restring the dial...

01-13-2017, 05:41 PM
Forgot to show pictures of my set..

01-14-2017, 08:57 PM
I've finally got the dial restrung and all back together. Now to put together a parts order and begin cleaning and testing tubes.

Phil Nelson
01-15-2017, 12:06 AM
Good work! Petrified grease seems to be almost universal in those continuous tuners.

Phil Nelson
Phil's Old Radios

01-15-2017, 03:26 PM
I ordered the 470pf 15K capacitors in the hv section. I also pulled out the 19AP4 and cleaned the face and neck area. I also cleaned the cabinet glass and dial plastic. This set had layers of dust and cobwebs between the crt face and glass. I tested all of the tubes and replaced one bad 5U4 and someone put a 6CD6 in place of the required 6BG6 horizontal output tube. I'm in the process of cleaning the hv section and ordering the other caps.

01-16-2017, 11:48 AM
Love these old DuMonts.

The RA-112 was one of the last good ones.:smoke:

01-16-2017, 01:53 PM
Awesome! Glad to see you got it. Is there any life in the CRT?

01-16-2017, 02:24 PM

The crt tests very good and is a RCA Silverama. It's a rebuild for sure, as I can feel and see the neck weld. This is one of the few metal coned crts that I've tested that actually tests great. Usually they test bad, but have enough life in them to be watchable. Thanks for the heads up on this one btw!

01-21-2017, 11:06 AM
My caps came in for the hv cage area so I finished cleaning and installing new parts in this area. Now I'm waiting on the rest of the capacitors to come in and get a new 6AL7 tuning eye from a fellow collector.

01-21-2017, 08:49 PM
Nice work.

Dammit. I want another DuMont.:smoke:

01-25-2017, 09:01 AM
After replacing all of the paper capacitors and most of the electrolytics, I was eager to see if I was going to get a raster. I hooked up my HD converter and slowly brought the set up on a variac. I received a nice bright raster, video and sound! I still need to replace a few electrolytics, adjust the yoke and replace the tuning eye. Success so far, seeing that big 19" crt light up!

01-25-2017, 10:05 PM
Ok, this set is officially recapped and looking great. Very sharp video, now I just have to align the audio so it's strong when the video is strong. Once I do that and replace the tuning eye, this set will be done.

01-26-2017, 01:23 AM

Also, Hogans Heroes!

01-26-2017, 02:08 PM
Ok, this set is officially recapped and looking great. Very sharp video, now I just have to align the audio so it's strong when the video is strong. Once I do that and replace the tuning eye, this set will be done.


Nice work. Check the tubes in the tuner and IF sections. It shouldn't need an alignment.:smoke:

01-26-2017, 02:41 PM
I KNOW NUTTINGK !!:lmao::tongue:

01-26-2017, 05:52 PM
When the video is sharp, I get hardly any audio. When I tune almost completely off of the station, audio is very strong. Do you think it's a tube causing this?