GE 810 restoration

[M3-SRT8]

Don't you love it when it's just a tube swap?

My second Admiral 24A12 would not synch in the Hor. axis. I had checked all components up and down the line.

It's over at my good buddy Dick Slade's house. He's a Renssalaer Poly Tech grad from the 50's. He found the problems. The Hor AFC Slug was broken. Turning it had little effect. A dab of JB Weld fixed that. Also, A 82K 1/2 watt resistor measured 95k, and that was enough to keep the Hor. Hold from locking in. I had checked it and figured it was close enough, given vintage TV's "wide variances" in components.

Guys like Dick Slade are worth their weight in gold. "The Professor" on Gilligan's Island has nothing on this guy..

[bandersen]

That's some fine troubleshooting. I'd never think to look for a broken slug.

I received kbmuri's inner brown knob and it's a great color match so I've got a complete set finally

I hooked up a test pattern generator and have been tweaking the picture.
This is what I have so far. The squares are larger in the middle than around the edges. I can make the top or bottom rows larger with the vertical linearity, but I need to make them both bigger (or the middle smaller). I've been fiddling with both the size and linearity and this is the best I can get.

Any thoughts ?

[Phil Nelson]

Well, the height and linearity are usually somewhat interactive, so I go back and forth between them until I've reached the best compromise. Yours doesn't look that far off. When I get tired of fussing with this kind of adjustment, sometimes I take a break and watch a movie for a while. You may discover that the discrepancy isn't noticeable unless you're looking hard.

Phil Nelson

[jeyurkon]

Some random thoughts.

I asume the squares should all be the same size. If so, the fact that both the horizontal and the vertical behave the same way might indicate a soft power supply. But, since you changed all the electrolytics that doesn't seem likely.

It has the correct yoke? The HV isn't too high requiring you to overdrive the deflection?

John

[bandersen]

Good points. Yes, they should be the same size. The yoke sure looks like the original. I'll pull out my HV probe and check the HV and all the other voltages for that matter.

I tried watching it for a while and the distortion is pretty noticeable on the taller actors.


I just remembered something. When I picked up this set I, found this cardboard piece loose on the CRT neck. The focus coil is a little loose, but this is too big to fit inside it

[Findm-Keepm]

Also, check to see if moving the yoke back some might help - my 1956 RCA had a linearity problem, and all I had to do was slide the yoke back a bit. I'm sure there's a trigonometric reason for why it went non-linear with the yoke shoved all the way forward, but I was definitely asleep when that was taught...

BTW, Your set's progress is far and away much better than I could ever hope to achieve. Do ya 'suppose the Smithsonian is envious??

Cheers,

[wa2ise]

Originally Posted by bandersen

I hooked up a test pattern generator and have been tweaking the picture.
This is what I have so far. The squares are larger in the middle than around the edges.
Any thoughts ?

As for the horizontal, many TV sets had a capacitor in series with the horizontal portion of the deflection yoke. Called an "S correction" cap. slows the sweep in the middle, and speeds it up on the sides. Don't know if your set used this. Maybe it went bad?

[bandersen]

Yes it did, and I haven't checked it yet. Thanks for the tip.

[kbmuri]

That could explain the horizontal bulge, but your horizontal distortion and vertical distortion appear very equal. I'll agree with jeyurkon that it's a PS issue.



Here's mine. It has a vertical issue so I have it cranked up pretty far, and the boxes are a lot taller than they are wide, but the respective spacing is pretty equal.





You may notice the same tubular piece of cardboard in front of my set, I couldn't get it to fit either. But even without it, my horizontal sweep is pretty linear. I don't think the lack of it is affecting your sweep.

If I bring the vertical size down to where the boxes are square, the centering is really poor, the top 1/3 of the screen is dark and the bottom is still just off the screen. I think maybe the cardboard tube out may have something to do with that. Or a physical mounting problem with the yoke. But that's a problem for another day. Haven't really worked much on this one, other projects ahead of it.

Glad the knob was a good fit, and glad I could help.

[kbmuri]

ps. the previous owner bent up the HV cover, not me. I will probably take it off and straighten it on the workbench with proper tools, paint it, and put it back on, someday.

[John Folsom]

Have you checked the performance of your pattern generator on a set with known good horizontal and vertical linearity? Sometimes test equipment is the problem, not the cure!

[bandersen]

Thanks for all the tips. Yes, the pattern generator is working properly

I noticed the old 5U4 glowed blue briefly during startup and replaced it with a NOS Westinghouse.
I also replaced the 6V6 vertical output tube which had a noticeable effect! I had more height and the linearity control was more effective.
Still need to check the horizontal yoke cap.
Here's what I've got now. I think it's pretty watchable

Odd that we both have trouble with that Jughead hat shaped tube

Notice that dark speck near the top center? That's actually a bubble of air in the glass! I have some in another early GE 10FP4 too.

Almost forgot - a new 560 10W focus coil resistor arrived yesterday. I'll pop that in and see what effect it has.

[John Folsom]

Lookin' GOOD!

[kbmuri]

Hard to improve on that, Bob. Looking great!

Looks like your changes might have picked up a drive line at the left edge of your set. I don't see a Horiz Drive adjust on this set. Wonder if it can be done...

Good point John F. Here's the output of my generator on the most modern set (a late '80's Sony Mega Watchman) I could find



Looks like a slight bend on the left side. Might be in the Watchman, too. I guess the only way to be sure is to use a lab-grade o'scope and check for straight sawteeth.

For benchtop work, it's more than adequate as-is.

[bandersen]

There are trimmer caps for horizontal drive and frequency next to the power connector. I tweaked them a bit and got rid of that line of the left