Not Quite Sure What To Call This
 

I'm not sure what term to use when describing the problem in the picture below. Any time there is a white to black image, the white will "bleed over". Smearing? In any case the picture below was the best (worst) image I could find to produce this problem. Can any one tell me what this problem is called, and what the possible causes of this problem might be?

http://farm9.staticflickr.com/8379/8...dd772f407b.jpg

Nobody have an idea? I have to say I can't guess why.

Also hard to see exactly what the symtpom is ...Hard to tell if the white bleed is actually starting AFTER the first line of white letters and continuing onto following lines, or is across the whole first line as well as every line.

Can you do anything to the controls that changes it? If so, that might lead you to the section causing trouble. Other than that, no clue. Any change with fine tuning?

If you have spare tubes, I'd try changing IF, video amp, AGC, sync separator.

What set is this?

The symptom is on every line. I turned the brightness up a bit to accentuate the problem for this picture. When you are watching a normal scene the problem doesn't look this bad, but it is definitely there. White text on black background is the easiest way to show the problem.

The symptom doesn't change with any control setting. It becomes more visible as the brightness is turned up, but the ratio of brightness of the symptom to the text doesn't change.

I'm almost positive that it isn't the IF. The picture above is using the entire set with an RF modulated DVD player, but I can bypass the IF stage completely with my B&K television analyst and the problem is still present. Unless the B&K is somehow causing the same problem in an unrelated way, it must be forward of the video detector.
There is no AGC in the set btw.

This set is my 630ts. I don't know if it is apropos to this problem but the contrast control on this set seems more like an on/off switch. There is only three different settings- no video- weak contrast- good contrast. Other sets that I have are more of a gradual even ramping of the contrast level from no video to over driven. I've begun checking the resistors around that area and all are good so far.

Hi All;
I would say check the Video section.. The video amp is not flat in its amplification of the video signal.. It remind me of a too narrow bandwidth.. But, it could be the IF section if it is not wide enough to carry the full bandwidth..
Thank You Marty

Hi all;
In my other book with pictures,, it says possible causes for trouble..
Contrast control set too high, overloading the the amplifiers..
Video IF amplifier wongly aligned, with the video IF Carrier too low on the side of the response curve..
Faults in the Video Detector and / or Video Amplifier circuits.. Check coupling capacitors, decoupling capicators and bypass capicators for open circuits.. Check Plate Load resistors and grid resistors for incorrect values or shorting.. Amplifier grid biases may be insufficiently negative allowing grid current to flow..
Those with more experience, might be able to elaborate..
THANK YOU Marty

would be interesting to see if you could see it on a scope. Need a fixed image of course and then look at each line of data (horz scan rate) compare the composite video to the output of the detector,then trace thru to the CRT grids (or cathode if that is how it goes).

Did you try a composite video injection at the video amp grid (sorry if you mentioned it already)?

Maybe just a weak CRT that the cutoff is not that sharp.

That's a correct assessment. The absence of any appreciable ringing or smearing-out of fine detail in the pic would rule out misalignment of the IFs.
The problem is almost certainly in the video chain. Have you checked the peaking coils for continuity? Looks to be eight of 'em sprinkled from the detector and the CRT.
If they're all good, injecting with your B&K point by point thru the video chain (attenuating as necessary) oughta spot the problem.
That sounds almost like the control is cruddy/scratchy. If you have an analog ohmeter, check to see if it runs smoothly from stop to stop without drop-outs or jumpiness.

I have another 10BP4 that doesn't give me as good a picture as this one. It displays the symptom as well.

http://farm9.staticflickr.com/8098/8...2d8d2cc35a.jpg

I'll give this a shot, but I am still extremely green with scope interpretation.

The coils are all good.
Unfortunately I don't 100% trust my B&K at the moment. I think it needs some servicing of it's own for a few reasons. It's quite a shame as this is precisely what it is good for. That will be my next project on the bench.

That 's what I thought also, but it ramps smooth as silk from 0 to 10k.

I think I'm going to go resistor hunting in my video section and see what I can find.

The Picture control on a 630TS is confusingly named. It is a manual gain control and its effect is not like a contrast control on newer TVs.

The Picture control varies the gain (i.e., amount of amplification) on the overall signal. You may find that it has a pretty narrow range where the picture & sound are acceptable. You may also need to readjust the Picture control when changing to a different source with a weaker or stronger signal.

To some extent, what you're experiencing is normal for a 630TS. 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.

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.

There was a recent thread in another forum by a guy who had similar horizontal lines (on a different television) that looked like overdriven video. I think they disappeared when he removed (or changed?) a modification he had installed to minimize retrace lines.

On a general note, if you go treasure hunting to check resistors, check mica caps, too. Micas used to be thought immortal, but now more and more of them are found faulty. When I redid my 630TS 1,000 years ago, an oldtimer told me to replace the mica coupling caps in the video IF chain.

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

If this was a solid-state TV, I would say it has bad electrolytic capacitors in the video circuits. Double-check the values of the capacitors replaced in those circuits.

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.

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.

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).

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

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

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.