Emerson 14" AC/DC suitcase TV

[DavGoodlin]

This obvious mid 50s set was sitting under my bench for a while and is quite a pandora's box. For the longest time, I could not figure out how to get it open.




I was looking at several collections like TV History and cannot find out what model this is. The chassis is stamped 333Z, which means chassis # 120333Z in Emersonese. Sams index lists set 299 (PCB 322), which I don't own. The 299 Sams is a series wired console, so thats not right.
The original 14HP4 is a 70 degree type and tested well into good range, then the needle started dropping back, which is odd.

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Several tubes were bad. Open heaters on 12D4 and 25DN6, shorts on a 12BY7 and 3CB6. Now for a look underneath.

Only one selenium so its not a doubler supply, hence it runs on DC also, but 120volts for the tube heaters will only give 120 volts B+, that's not much.
On AC the B+ would be more like 140, all the electrolytics are rated for 150 WV.
I plan to replace the selenium and bring it up on the variac.
I see alot of crummy caps but I want to see a raster before diving in here.

[Electronic M]

Might be interesting after you get it working to full wave rectify the AC out of a variac into a big lytic, and run the set off of 120VDC to see how well it works as a DC set.

[Eric H]

Probably a model 1146 from 1956.


I had a black one but it was in such bad shape I junked it, I may still have the chassis though.

[DavGoodlin]

That model number has teh same listing in sams.
I will need to get 322-1 at some point but I can recap this little cutie without it, as it appears only electrolytics were the only repair besides tubes.
Thanks Eric!

[dieseljeep]

I have two of them.
One, a year earlier. Not designated AC-DC, otherwise identical.
The CRT is flat dead in the newer one. Original one, Emerson branded with an EIA source 158, which is Dumont.

[Zenith26kc20]

I have the mahogany metal cabinet version. Very good performer! For such a simple set, they are fun to watch and reliable once gone thru!
And the clunk-clunk tuner to boot!

[dieseljeep]

Originally Posted by Electronic M

Might be interesting after you get it working to full wave rectify the AC out of a variac into a big lytic, and run the set off of 120VDC to see how well it works as a DC set.

It'll show a slight underscan of the horizontal sweep.
The set's were really designed for 140 volts B+, when used on AC.
I think, most commercial DC sources were probably higher than 120 volts.
Plus, there's a lot more voltage drop in a selenium rectifier, than a silicon rectifier.

[Jeffhs]

Why would any TV manufacturer design their sets to operate on DC power? Almost all home electric service in the US and probably Canada is 115 volts, 60 Hz AC. I can understand designing TVs to operate on 50 Hz AC current, but AC or DC? DC power would almost certainly destroy the power supply in an instant.

The only thing I can figure is Emerson must have meant the set was transformerless. I cannot believe, however, that this set could also operate on batteries--the only other explanation I can come up with for any kind of "AC/DC" designation for a tube-powered television. The tubes would eat up batteries in minutes, if not seconds.

[old_coot88]

Originally Posted by Jeffhs

Why would any TV manufacturer design their sets to operate on DC power?

These kinda sets were not "designed to" run on DC. It's just that a line-operated power supply using half-wave (single diode) rectification can run on either AC or DC. (If on DC, reverse the plug and nothing will happen).

The only thing I can figure is Emerson must have meant the set was transformerless.

Many transformerless designs used voltage doublers (with two diodes) and can't run on DC.

[Jeffhs]

Why on earth did Emerson even mention that this portable would operate on DC power? Were there some areas of the United States or Canada in the early 1950s that actually had DC house current? I am asking these questions because, until now, I had never seen the term "AC/DC" used in connection with tube-powered television sets, only AA5 tube radios. (DC power would, of course, destroy a power transformer and its associated rectifier tube in no time flat.) The DC power option almost always went unused in AA5 radios used in the US, although there are, of course, three-way (AC/DC and battery) portable sets.

I guess the use of the term AC/DC in connection with televisions using tubes just threw me for a loop. I had a 1955 Emerson 17" portable TV years ago, but there was no mention of AC/DC on the cabinet; the logotype below the CRT only showed the brand name "Emerson" in script lettering. Was the Emerson AC/DC set under discussion here a limited edition, or was it just a cheaply built portable not meant to last long, not unlike the cheapies that came off the lines from Japan in the '60s-'70s--not to mention today's flat screens? I believe the Emerson "AC/DC" portables were designed to be used as second or third sets in bedrooms, guest rooms, etc., not as the main watcher, although I suppose a few of these sets were used as the primary TV in small apartments where space is limited.

[pearsonk]

According to Wikipedia, 110vdc was still being used on a limited basis in some metro
areas well into the 1960's............

[Chip Chester]

I like that the illustration shows the model carrying it with one hand, not a care in the world. The set is probably 40-50 pounds maybe?

Perhaps the DC option was for vacation/hunting cabins, with 10 car batteries in tow. But I doubt the late 50s were quite so media-centric as we are today.

Chip

[DavGoodlin]

Originally Posted by Chip Chester

I like that the illustration shows the model carrying it with one hand, not a care in the world. The set is probably 40-50 pounds maybe?

Perhaps the DC option was for vacation/hunting cabins, with 10 car batteries in tow. But I doubt the late 50s were quite so media-centric as we are today.

Chip

Most luggable TV's of this era had transformers or a least selenium rectifier doubler supplies, making them AC only.

In those days, DC set operation was likely attempted by a few where AC power did not exist BUT a good signal didI would have certainly tried it, rounding up a dozen batteries as I was very much into antennas and DXing.

In my youth, we had a cabin in "the mountains" with no electric, used to have a 12 volt battery and the 1970 Sony TV-720 BW. Two VHF channels from two antennas in different directions. One was an NBC from Johnstown, so we never missed SNL on the weekend.

[dieseljeep]

Originally Posted by pearsonk

According to Wikipedia, 110vdc was still being used on a limited basis in some metro
areas well into the 1960's............

You beat me to it!
110/220 volts DC was very common in the Downtown Elevator districts in large cities. Some of the buildings were residential and the living areas were equipped with DC circuits. Many of the units had gas refrigerators, as electric refrigerators weren't made for DC, unless they were the Ammonia type, like gas refrigerators.
The Emerson distributor, that was north of the Milwaukee downtown area sold a lot of them and the tech that worked there said they still get them in for repair. That was in the mid-to-later 60's.

[dieseljeep]

Originally Posted by Electronic M

Might be interesting after you get it working to full wave rectify the AC out of a variac into a big lytic, and run the set off of 120VDC to see how well it works as a DC set.

I had a little fooling around time, so I tried my 1146 on a DC source, as close to pure DC, as I could come up with. It's a power supply using a full bridge rectifier and a 470 mf 'lytic cap.
It actually works rather well. I metered the DC voltage being fed to it. Three different levels, 105, 110 and 120 VDC. Slight horiz underscan at 105 volts.
Emerson did design sets for the DC market, this set and the 7" set, that came out years earlier.