Problem with Vertical for Philco 49-1075, Any Help?
 

Hi all,

I'm hoping that you can all give me a helping hand with completing my first TV restoration. I am, however, very experienced in tube radio restoration. According to some, I am having a much more difficult time with this TV than is normal, and I'm looking to see if there is someone here to can help.

The good news: I get some response out of the TV. Here's what's been done to it...
-The picture tube seems to work fine, I've aligned the magnetic ion deflector at the back of the picture tube, and replaced roughly half of the tubes (the ones that I knew were bad).
-I even replaced several mismatched tubes with the appropriate values.
-The contacts were cleaned
-All - absolutely ALL - capacitors were replaced
-The controls were cleaned
-The doorknob cap was a bit leaky and was replaced
-The candohm resistor was replaced
-The vertical output transformer was assumed to be shorted, then confirmed not shorted, but was replaced anyway.
-Injecting a signal gets sound out of the speaker
This TV chassis seems to be in tip-top shape now

The bad: I cannot get my picture on the CRT to scale the full length of the vertical. Try as I might, the picture's horizontal is good - it spans the width of the CRT. But, I cannot manage to get it to get higher than about 1/2" in either direction of the exact center of the picture tube. It creates a 1"-tall line all the way across the tube, with a distorted version of the picture for my injected signal showing within that line. A photo of this is attached.
http://i.imgur.com/9li50xn.jpg

I'm at my wit's end with this chassis, and I've spent so much time and money on it that I'd like to actually get it working. I have traced all - absolutely all - resistors in the vertical section of the chassis, and have found absolutely no problems with any of them. I still, however, get some wacky voltages on the leads of the 7N7 and 7F7 tubes, and cannot for the life of me trace why this is happening. I have also attached a full schematic of this set, with the strange voltages noted in the schematic/"V" columns of the table, and the voltages that each tube SHOULD have in the "V Original" columns of the table. These are below, in large format for easy readability..

Thank you all very much in advance for your help!

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http://i.imgur.com/4RdIAof.jpg
http://i.imgur.com/Kb7rfEj.png

SOME ADDITIONAL DETAILS:

-The vertical output tube was replaced with a new one.
-The pins of each of the local tubes have been cleaned and re-cleaned. When the TV is fired up, and I move the local tubes in the vertical circuit (The 7N7s and the 7F7s), no change in picture. I believe that they're all making contact.
-Replacing the tubes that I had found in the set originally with new ones of the correct values makes 0 difference in picture.
-Riders TV Series doesn't have my set
-I did try wiring the original transformer back in, and no change in picture once again
-Sorry, my estimate was off. The raster is probably 2" high.
-I tried my damnedest to replace the capacitors in the set with capacitors of EXACT value when replacing the caps.

Where should I start in searching for a problem?

Can you get any vertical variation by adjusting the height and vertical linearity controls? Any change in number and width of the diagonal lines when you adjust the Horizontal hold? 49-1075 is in Riders TV 2, pages 141-196.

If you changed any resistors in the verticle you may want to double check the values. As I had made a mistake in a set in the verticle with the wrong resistor and could not get it right either. It happens to even the best.

Looks like your horizontal is way off freq, why don't you adjust that & see what
you get for a picture.

Vertical too for that matter, if the frequency is way off the picture can collapse like that.

Hi all,

Thanks for your responses!

The resistor suggestion has been checked, and all resistors are verified the correct values. Immediately after I replaced all caps and plugged this in, the picture was the exact same as it was after I replaced several of the resistor that I thought were "out of spec." So, in short, anything I've done so far resistor-wise has not affected the picture whatsoever.

I have heard the horizontal suggestion before - no matter what I try, this is as good as I can get it. Why would it be the horizontal?

As for the vertical and height linearity controls question, I have adjusted all that I can and the photo above is as good as I can get it after adjustments.

So, back to the horizontal question: how exactly would I "adjust the horizontal"? As previously stated, I've heard that before, and after adjustments to 'the controls" this is all that I seem to be able to get. Can someone please explain to me, and include photos if necessary, exactly what you mean by "adjust the horizontal"? For all I know, I have been "adjusting the horizontal" wrong this entire time.

Thanks!

Many vintage TVs have an adjustable coil that sets the free running horizontal oscillator frequency. It's usually at the back or under the chassis and acts like a coarse horizontal hold while the horizon hold at the front of the set is used for minor corrections.

It appears that yours does not. It only has a single horizontal hold control. That makes me think that component values are especially critical.

Particularly C513, C516, C517 and L501 in "SECTION 5 - SWEEP"

The reason we suggest getting the horizontal fixed first is that you will then have a viewable picture on the screen.

Even if it's short it can tell you a lot about what it wrong with the vertical, is it folded over, it is short on top or bottom, is the linearity good, is it rolling, and so on, and that can make it easier to figure out where the problem is.

As banderson said, the values are critical in the Horizontal, double check everything around the 7F7 Horiz Sweep Generator, including the horizontal hold control itself.

This is a difficult set to obtain voltage readings from while assembled, based on your description of observation. Assuming both H and V are off-freq, Are you able to feed a signal in and see multiples of a "rolled up" picture?

Never, ever underestimate how "far off" a post-war set can get on both sweep frequencies.

In the meantime, one thing you need to do is get a tube socket extender for both octal and loctal tubes so you can scope and meter those tubes in operation. I have neither of those extenda's myself. But I do have a CRT available if you bring the chassis and yoke/focus coil with you.

That way, we can sub in some vertical drive from a Sencore VA48 or a B&K model 1077B analyst to the 6K6 grid and clear your output stage. sometimes you need "modern" equipment to nail down trouble in early sets.

Hi. To me the slight waviness on both sides of the screen looks like Open, leaky, or, shorted electrolytic sections. Also, I agree that fixing your horizontal first could be a big help. In fact, if something is amiss in your boost circuit, it could cause many problems. Please don't try to test voltages in boost circuit. There is a high AC pulse, and, it would blow your test equipment.
If your brightness doesn't seem quite enough, your hv voltage may be low, which would be a [pomter to the boost circuit.
Also, it's very important to replace everu paper capacitor in the entire set.Even one leaky paper can raise havoc.
Good luck. If there is anything else I can do to help, please feel free to ask.\
I have over fourty years of electronic experience, I learn something new to learn amazingly often...
Bill Cahill

This photo shows extenders:

https://antiqueradio.org/art/predicta23.jpg

Note the blue one plugged into the chassis. The little terminals on top of the extender allow you to make voltage and resistance measurements on each pin from the top of the chassis.

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

Have you checked the disc capacitors which have a tendency to drop dead?
or, the vertical output transformer?
Bill Cahill