Stromberg Carlson TC-19 horizontal line
 

Hi all. I got an old Stromberg Carlson TC-19 TV from the late 40's or early 50's. It does power on, and I can get audio fine, but it only gets a single horizontal line on the screen. Tubes are new to me. I am trained in electronics but my training only covered solid state and digital, almost nothing about TV, radio or vacuum tubes.

I have been studying vacuum tube theory, and I do grasp most of it now.

I have the schematic and have done some diagnostics but am at a loss what I am missing. I have tested the yoke and seem to have continuity there. I know the problem must be in the vertical circuits some where. So I will be asking some questions when I get this set opened up again. I also know a full replacement of the old capacitors should be done to this thing at some point.

Here are some pics.

Dave , I don't know if you've been told this before , but DO NOT allow that horizontal line to remain on the screen at anything close to full brightness as this will burn a line in the CRT's phosphors that will result in that area being a "dead spot" forever on the CRT . Any power on testing from here on out must be done with the brightness set at the barest minimum to get a barely there faint line so the phosphors aren't damaged (burnt) untill you restore the vertical deflection . A set such as this will require a "recap" , replacement of the electrolytic capacitors in the power supply and vertical circuits as a beginning of your restoration of the set .

Welcome Dave. You are correct that you have no vertical deflection. The vertical circuit is fairly straightforward: oscillator, output amp coupled through a transformer to the yoke.

Here's the order in which I would check items:

1. vertical stage tubes
2. get a schematic and check voltages on the tubes.
3. use an oscilloscope to check the waveforms.

While you have no vertical deflection, be sure to keep your brightness very low so you can barely see the horizontal line. Otherwise, you could burn the phosphor on the CRT and have a permanent horizontal line.

Also, until you replace the capacitors (especially on the power supply chassis), do not leave the set unattended while turned on and pay special attention to the power transformer. If it starts to get too hot, you may need to immediately replace those electrolytic capacitors.

Good luck.

Thanks. I do know to not let the screen "burn" with that line. I only left it on a very short time. And have turned the brightness down to a minimum.

A google search tells me another member here has this same set he is working on. I will try to contact him for more info. Maybe he has already made a list of caps to replace. That would sure save some time.

Hey, that would be me :) Nice to know there is another surviving examples of this model.

Here's the thread: http://www.videokarma.org/showthread.php?t=263969

Sorry I haven't started work on it yet and don't have a parts list. When I work on a project, I get most of the parts from my local inventory. I'll combine what I need with several other projects to build up a big order. Makes it hard to separate out specifics for just this project.

I can tell you this - all the paper caps and electrolytics should be replaced and there are a lot of them. This was a top of the line model and fairly complex.

If you have the Sam's or riders manual for it there should be a parts list. All the lytics (they will be in the 2-200uF range and be rated for 25-500v) and all the papers (rated .001-1uF usually 100-600v) should be changed. There will be mica and ceramic caps in the original parts list too... Ignore them, they virtually never go bad.

Check the vert output transformer and vert osc transformer(if it has one) for correct resistance and for primary to secondary shorts before spending money on caps. Also check the vert tubes...odds are the caps are the problem, but tubes are also likely. Bad vert transformers can also cause it, but are much harder to get replacements for (so try to have a good one before sinking time/money in).

Another mild possibility is an open or severely drifted resistor in the vert stage... even if they are not causing the total lack of vert sweep if they are outside tolerance ratings they will cause the vert to be non-linear or off freq once you get vert sweep back.

Lastly if you have the schematic check all the B+ rails that feed the vert stages... if any of those voltages are missing or over 30% low that can stop vert sweep too.

The vertical circuit is probably the most trouble prone of any. An out of spec capacitor that you'd never notice in an audio circuit can cause all kinds of trouble that you can see on a screen. There is a very good chance, I've found, that recapping the entire circuit can bring things back to life. Regardless, it has to be done if you're going to have a decent picture.

In your third (from the left) photo, I see what looks like a big strung pulley, of the type more usually seen in radios. Is that part of the tuner? Some control?

Just curious . . .

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

Yes it is part of the tuner. It has a complex mechanism that uses cable from the front panel down to this tuner section. That turns the string, then it ends up moving the 4 cores to inductors up and down with some gears.

vertical output transformer is common on these sets and not hard to find should be a 10 to 1 ratio there on ebay. I bought few spares.

I'm trying to find some more info. The yoke installed on this is a Stancor DY-9 70* yoke. It looks like it was a replacement at some point. The data sheets only list a Merit replacement part. The merit part number is MD-12. From my research this is a 53* yoke for tubes 10 to 16 inches. Something is just not right here. This is a 19 inch tube. My searches also have failed to find what is the correct part equivalent to this Merit number other than RCA 201D1, 201D3 or 201D12. And I have no luck at all with those RCA numbers.

My next step is going to be a full replacement of caps. But I want to make sure all the other parts are correct also. I have ordered some of the tubes that had been replaced with different number tubes as well. But this yoke is bugging me.


First, can anyone tell me what part is supposed to be here? And can you give any advice finding a correct replacement?




I got one coming. Stancor A-8115 is what I got off the big auction site. It is listed in the parts list replacement data section of the PhotoFact I got for this.

The Thordarson cross reference lists Y-5, 70 degree, replacement for the TC-19.

Thank you Tim, this really helped. I was able to cross reference the Thordarson Y-5 to a Ram Y70F08 and I have a lead on one. I Hope I can get it soon.