Not Quite Sure What To Call This

[vts1134]

Originally Posted by Phil Nelson

At one end of that control's range you'll get almost no signal, and at the other end you'll get wackadoodle picture & sound.

That's exactly what I was expecting with the control, but at one end I get 0 signal, when I turn it up at one point I get low signal followed immediately with normal signal. What I can't get is the wackadoodle picture no matter how high I crank the control.

Originally Posted by Phil Nelson

Bear in mind that 1940s TVs were designed to be watched in dim lighting. I suspect we're all guilty from time to time of cranking the controls up too high and expecting these old sets to have an ultra-bright screen like modern TVs, that you can watch in a sunlit room.

I will admit that I am guilty of that from time to time. When I set the brightness control at it's proper value for viewing in a dimly lit room, and the source is full motion video, the problem is almost unnoticeable. Almost unnoticeable doesn't mean the problem doesn't exist though. It needs to be found and repaired.

[old_coot88]

Phil,
Did your 630ts exhibit any sign of those full width 'ribbon lines' that Vts1134 is chasing? Sometimes ya gotta wonder if certain quirks in the old sets aren't just the nature of the beast (like the horz nonlinearity in your T-100, wherein i had the identical problem in a T-100 many years ago and never could run it down).

[Phil Nelson]

I honestly don't recall if my 630TS showed those lines, although I know I have seen similar lines in some old TV or another during the last several years. Maybe tomorrow I can fire up the 630 and look at some images. It's in a location where it looks pretty but rarely gets played.

The content that we watch today has lots of lettering with extreme contrasts --static title screens, screens with text crawl at the top and bottom, etc. -- which brings out the worst in some old TVs.

Phil Nelson

[Phil Nelson]

I was too curious to wait, so I played my 630TS and it doesn't show those lines, even on static title screens with extreme contrast.

Turning the Picture control from one extreme to the other gives you no signal at the CCW end of the range, and then if you turn it up (CW) too far, the picture distorts and eventually loses sync.

The tuner has gotten a little flaky, no doubt from sitting around without being played. I really need to go around and exercise all of my restored sets more often.

Phil Nelson

[vts1134]

Thanks for looking Phil. I wouldn't describe this as full width ribbon lines in the picture. The trailing white only happens to the right if the brightness control is set to a normal level. It's like some one takes the right hand edge of a white object and pulls it out horizontally to the right.

[old_coot88]

Originally Posted by vts1134

...I wouldn't describe this as full width ribbon lines in the picture. The trailing white only happens to the right if the brightness control is set to a normal level. It's like some one takes the right hand edge of a white object and pulls it out horizontally to the right.

Oh, so the lines on the left appear only at max brightness but not at normal level. Right?

For the heck of it, double check the value of R138 (grid leak resistor of 1st video tube V115). The print is really smudged but it looks like 475K.

And double check R140 (plate load resistor, 3.3K)

Pin 2 (suppressor grid, G3) is grounded. Check to be sure the tube's pin actually makes contact thru the socket to ground.

Wiggle V115 and V116 in their sockets and see if there's any change in the wackadoodle lines.

Did you try subbing V115 and V116?