DuMont 181 Restoration

The sixth pre-war television to grace my collection is this 1939 DuMont Model 181 television with radio, original price was $540.00. Electrically & mechanically it is nearly complete, just missing the knobs and some radio trim pieces. The cabinet is structurally sound, but will need some new veneer and a couple of pieces made. I plan to document the restoration here as I make progress on it. I am hoping to have it completed by the end of 2009.

The set is quite large 48 1/2" high, 23" wide and 26" deep, it has 22 tubes including the CRT. It has a 4 channel tuner, the CRT is 14" diameter, which displays a 8" x 10" picture. The radio, an Andrea PE8S chassis, has 8 tubes, covers 3 bands, TV and radio have separate speakers and operate independently of each other.

Of all my pre-war televisions this will be the the most involved, it will need the most mechanical work of all the others. It was not stored in the best of places, so as you will see there is a lot of surface rust on the parts.
There is only 1 other Model 181 known to exist, in the Smithsonian Museum collection.


After inspecting the chassis and comparing it to schematics in Riders, a few differences were uncovered. In the upper right corner of the chassis above, a new filament transformer for the CRT has been added. You can see the original wires coiled and secured to the shield near the center transformer, I don't yet know if there was a problem with the original or if it was an engineering change.	In this picture you can see the new HV rectifier socket that was added to produce the needed +4000vdc for the 2nd anode connection of the later style CRT's. The -4000vdc rectifier socket is behind the IF transformer (20-107).

Repair tag that was found attached to the chassis, this side notes the owner's name and address. I believe it reads:
Father Connor
239 Anderson Ave.
Cliffside Park NJ

Looking at Google Earth, there appears to be a church and rectory still at this address.

The reverse side of the repair tag appears to have a description of work done to the set. I was able to decipher a few lines with Photo Shop using various color gradients.

(Unreadable)

Aligned Audio IF

RF & (unreadable)

3/14/46 R.A.

CRT 6 V72 F

Replaced

Q 396

No Charge

Above the radio front panel, missing are the knobs, pushbuttons and pushbutton bezel. This Andrea radio is the same as that used in the prewar Andrea 2F12, and 8F12 televisions.
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May 5, 2009

I was able to get an original pushbutton bezel and pushbutton cap to have duplicates made.

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On the right is the radio chassis, complete but needs so much cleanup work that I would like to find a complete Andrea console and swap it and find the missing bezel and pushbuttons. This chassis was used in a few Andrea models; 2E8, 4E8, 6E8

The CRT is a K1003P4 (12"), the post war replacement for the original 114-9-T or 14AP4 tube. This one is dated 1946, the tube is still under vacuum but I don't know if it is a working tube. I will be testing it in another Dumont set soon.
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May 5, 2009

I was able to test the CRT in a Dumont 180 thanks to Steve McVoy at the ETF Museum.
During the convention this weekend I installed the tube in the museums' Model 180. At first I thought the filament was out, but after a short time it lit and a watchable picture came on the screen, it was a bit silvery looking in the beginning but after running for 10 minutes it got much better. I think it just needs to burn off the cathode for awhile and it will look good.

I was also able to borrow an original set of knobs to get duplicated.
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August 12, 2009

Not much has been done with the set since the last entry, I have located a source for the high voltage wire used for the CRT socket. It is an exact match for the original. No updates on the new knobs, I will be taking the cabinet to the cabinetmaker before Labor day. Still no luck locating an Andrea radio to use as a donor, getting to think they are as rare as a prewar TV.

Have been able to purchase all the missing tubes, all Arcturus branded as originally in the set. Haven't been able to find a spare 6R6G.

Probably going to miss my 2009 completion date.

December 25, 2009

Well, I definitely will miss my restoration date for 2009, maybe summer of 2010....
Cabinet didn't make it to the cabinetmaker yet. Maybe next week....

I was able to locate a glass beading machine that I could use to clean the chassis on this set. Last week I took the radio chassis there and cleaned the 70 years of rust and crud off.


The front of the radio chassis before glass beading. The dial plate has been removed.	The front of the radio chassis after glass beading.


The top of the chassis before glass beading.	And after glass beading

The glass beading does a great job of removing the rust, but it does create other problems. The glass beads turn into glass dust after hitting the chassis, this dust gets into everything. After beading the chassis all the controls & moving parts need to be blown out with high pressure air and then washed out to get all the dust out of all moving parts. The other problem is being careful around wires and other "soft" parts, even if you don't blast directly on to the piece the over spray will eat insulation off wires and remove markings very quickly. I didn't cover the tube sockets and the over spray removed the tube number ID that was printed on the sockets, peeled the insulation off the dial lamp wires and also I managed to remove the voltage selection labels around the switch at the top of the transformer.

When I do the TV chassis I will need to take extra precautions to not repeat these mistakes.

January 15, 2010

The cabinet has been delivered to the cabinetmaker, I'm hoping for an April completion.

Started to disassemble the TV chassis, I have the front and the chassis supports removed. The front is made of plywood and is starting to delaminate, so I am going to have a new board made. The TV speaker and some of the chassis parts have been glass beaded to remove the rust and corrosion. I've ordered plating material to re-plate the metal pieces with chromate, a safer replacement for cadmium, cadmium is too toxic to do at home.

The bottom chassis containing the HV and LV power supplies, video and audio IF, and tuner. The next item on the check list is to test the power transformers. I will remove them from the chassis so that I can clean the rust from the laminations, if they are good I'll repaint them and cleanup the best I can. If bad they will be shipped out to be rewound.

The large HV capacitors I will open and put modern capacitors inside, the LV capacitors are the single hole mount style, hard to re-stuff so I have new that are very similar to the originals.

January 24,2010

I've disassembled the chassis' and cleaned the top sweep chassis and middle shelf with the glass beading machine.

I began removing components from the top of the bottom chassis in preparation of cleaning it. After removing the two power transformers and testing them - MAJOR setback, the high voltage transformer is bad. This transformer supplies both the 4,000 volt and 1,500 volts to the CRT and sweep circuits, one half of the 1,500 volt winding is open. I attempted to repair the break which I was able to find, but it only lasted a few hours. This morning I contacted Harbach Electronics, they purchased the Peter Dahl Company that made custom transformers, about having a replacement made. I sent them all the particulars about the transformer, now I have to wait and see what they can do for me.

February 22, 2010

The HV transformer is ordered, they quoted me a 3-4 week lead time and $400. I hope to have it in hand by the end of March. Another slight drawback, the place that I ordered the reproduction HV wire is out of stock. I have re-stuffed all the HV condensers with modern units.


Modern 4.7uF 1,500V	Reassembled Can	4 x .1uF 4,000V to make dual .2uF	Reassembled Can

The NOS low voltage B+ can type capacitors I ordered to replace the originals ended up being bad, I tried to reform them but gave up and even though a couple seemed to reform I just didn't want the hassle of replacing them again. So I cut them open same as the HV units above and restuffed with modern axial lead capacitors.

The set as shown in an early Dumont catalog

My cabinet

The chassis is complete, there are a couple of items that have been damaged over the years. One shaft has been snapped off and a couple of the control shafts are bent. Dirty and surface rust.

In this picture you can see the new HV rectifier socket that was added to produce the needed +4000vdc for the 2nd anode connection of the later style CRT's. The -4000vdc rectifier socket is behind the IF transformer (20-107).

This shows the addition of a coil assembly wired into the horizontal oscillator/deflection circuits. I haven't traced out the circuit to see what it is doing.

Repair tag that was found attached to the chassis, this side notes the owner's name and address. I believe it reads:
Father Connor
239 Anderson Ave.
Cliffside Park NJ

Looking at Google Earth, there appears to be a church and rectory still at this address.

The reverse side of the repair tag appears to have a description of work done to the set. I was able to decipher a few lines with Photo Shop using various color gradients.