Adjusting picture on Philco Predicta

[ISawItOnTV]

I'm attempting to adjust the picture on my Predicta and need some pointers on where to start. Basically, all I have is this pattern off the Disney WOW disc, and a screwdriver. As you can see, the squares on the left of the screen are not uniform with those on the right. I've made adjustments, but I seem to be making matters worse (since I took this pic).

The inner pot controls are:
1. Vertical Linearity
2. Height
3. Horizontal Range
4. Width pot (located at rear chassis)

And, there's the picture tube adjustments for centering.

So, what is the best order in making these adjustments?

[Phil Nelson]

I don't think the order of adjustments is critical. These adjusters are usually interactive -- that is, changing one adjuster also affects another parameter somewhat -- so you often need to go back and forth between adjusters to get the best screen geometry.

For example, adjusting the horizontal width may affect the horizontal linearity, and vice versa.

Your image looks like it is not quite centered horizontally. You could start with the horizontal centering adjuster and try to move the whole image somewhat to the left. After it's centered, then you can play with horizontal width and linearity to get the best compromise. Decrease the width until you can just see black bars on the edges, then increase it just enough to fill the screen horizontally. That may change the linearity a little, so touch up the linearity and see how it looks. If the centering seems to have changed a little, touch that up again. And so on. As you go back and forth between adjusters, you'll learn how they affect each other.

I use the term "compromise" because on some TVs the screen geometry will never be absolutely perfect. The horizontal non-linearity in your picture is noticeable in a test pattern, but you probably wouldn't mind it as much when watching actual programs. If you get frustrated with adjustments, take a break and watch an old movie for a while. That will give you a better idea how much a particular geometry imperfection affects your viewing enjoyment

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

[earlyfilm]

Originally Posted by ISawItOnTV

Basically, all I have is this pattern off the Disney WOW disc, and a screwdriver.

I am not familiar with the disc you used, but it looks to me like a wide screen test pattern.

First check the same DVD on a wide screen TV set and confirm that you are not attempting to set up a 4x3 TV to a 9x5 test card.

James

[ISawItOnTV]

Yeah Phil, the interactivity between all the controls was driving me bonkers. But, I got it as close as I can going between the pattern and TV programs. Thanks for the tips.

Earlyfilm: yes, that pattern is a 16:9. I thought it would scale down on my DVD player set to 4:3, but it stayed the same. Anyway, I was just trying to use the center area to help with the adjustments. I probably should download a 4:3 test image and run that through my player.

Here's the final result:

[Electronic M]

One horizontal adjustment that can help is the horizontal linearity control...It is usually and adjustable coil and may require a plastic hex key to adjust on a set of this age.

[Ampico-kid]

I've done a number of Predictas and considering the generally bad geometric distortion that seems to plague these sets (among other things), I think your set looks pretty darned good. I don't think I'd mess with it any more.
Bob

[7"estatdef]

Looks good to me too! I wouldn't fool with it.
Terry

[old_coot88]

Mega dittos to the last two posts.