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.

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?

I have also been restoring my 630TS and after the replacement of all the paper caps, all the electrolytics, and all resistors out of tolerance by more than 7% I recall seeing a similar (if not the same) image while using my little 5AXP4 test CRT. Unfortunately I did not take any pictures of that problem. Since then I have spent several days struggling with the video, audio, and tuner alignment. This is my first attempt at aligning a tuner, so I could be completely wrong. Most of my struggle was with the tuner alignment which ended up being solved by carefully selecting the 6J6 tube that worked best (alignment sweep response pattern wise) in each of the three tuner 6J6 positions. It went from only getting a weak picture and no sound of channel 3 on tuner channel 4 to getting a good picture and good sound of channel 3 on tuner channel 3 and channel 4 on tuner channel 4. I found that I had to perform the video and audio alignment again after the tuner alignment to get the video and sound right. The final video alignment was able to flatten the response curve, but not as good as the alignment figure in the procedure. Here is an picture after the final tuner and IF alignment. Its not well focused yet but I do not seen any smearing now. I still need to go over the horiz/vert linearity and size adjustments once the chassis is back in the cabinet.

Hi All;
I like what your screen says -- Your TV or its cables are NOT HD -- ..
That says it all..
THANK YOU Marty

Fine detail in the pic doesn't get much better than that. "Proof is in the puddin'" as the old saying goes. I would call it a day on the IF alignment.

Thanks, I'm happy with the way the alignment turned out as the sound is as good as the picture, unlike my 721TS. I will have to take another shot at its alignment, before I forget the details :D.

Dave

Yeah, I grabbed the remote to try to find some text like vts1134 used to show the problem. When I saw the DirecTV's low-res warning text I thought it was kinda cool. May not be HD but I really like this set (now that it works :D).

Dave

Here's that other thread I was thinking about:

http://www.videokarma.org/showthread.php?t=257163

His symptom was different -- full-width horizontal lines with some vertical folding -- and you don't have a retrace mod to un-install, but the discussion may be mildly interesting.

If you haven't already done so, may as well follow up on old_coot88's most recent suggestions.

Phil Nelson

The usual cause of video streaking, in your 630, in order of probability is:

1) Gassy tube in video, DC restorer or CRT.

2) Plate to grid coupling cap is leaky in video or CRT circuits. In a 630 there are four .05 caps doing the coupling.

3) Grid or cathode resistor in video or CRT circuit has gone high.

4) Circuit in general around the DC restorer, especially the one meg ohm resistor from cathode to plate.

5) The internal resistance and capacitance of the B&K has overloaded or detuned the tube at the injection point.

6) The B&K itself has the problem.

James.

Sorry for the delay guys. I have been crazy distracted with another set that I recently acquired. I'll post details on that gem soon.
I got back under the 630 for a bit this evening. I checked the resistors in the video circuit. Three resistors seemed a bit high to me. R138, the grid leak resistor on the first video amplifier is supposed to be 470K and it reads 570K. R148 (grid leak on the CRT?) is supposed to read 100K and it reads 125K. Those two are still fairly close but the worst offender is R147 which is supposed to read 3300 and it reads 4800. I will replace as necessary and report back.
I have not tried subbing V115 and V116 as I do not have replacements. Also my B&K is not causing the problem as I am using a modulated DVD player for these shots. The B&K was my first suspect so I wanted to eliminate that possibility.

Your audio is working fine, correct?

Once you have changed out the high resistors, borrow the V106 and V109 from the audio for testing the video.

Jas.

The audio is completely out of alignment. I can got some FM radio broadcasts on some stations so the audio amplification stages do work, but the entire section is not functioning as it should yet. I am planning on moving to audio when I finish with the problems in the video section.

I got back under the chassis tonight and got R147 down to 3300 ohms. I can't quite tell if it made the problem less noticeable. I reported earlier that the controls on the set didn't affect the problem, but I did figure out that the higher I set my picture control the less noticeable the symptoms becomes. When the picture control turned all the way up the symptom is much reduced, although definitely still there. The overall picture also lacks good contrast which could point to that area. I've started to do some resistor checking in the picture IF section, but nothing is standing out yet. I feel like the picture control just isn't adjusting the signal like it should. As Phil stated before:
My picture control at one end is 0 signal and the other end seems like it should "go further".

Looks to me to be something with the IF or the detector...

How is the vision IF Alignment? Detector OK?

I'm turning back to this thought. I've scoped the video output of the set and it confirms this description. At one end of my picture control setting I have no video, as I turn up the control I get a gradual increase in signal but at about 1/3 of the way up the signal stops increasing. When I meter the impedance at the control itself I get the results you see in the video below. I am adjusting the picture control at the same rate for the entire time the video is being shot.

http://www.youtube.com/watch?v=jmCvh9sm0Wg

Would this point to a malfunctioning picture control pot?

It's possible this is intended - an "audio" or approximately logarithmic taper. I don't see any obvious jumping that would indicate a bad pot.

Is this the original pot? If not, it may have been replaced with the wrong one.

If you can measure the voltage range at the wiper, you might try disconnecting it and substituting a power supply that lets you adjust the voltage over a somewhat larger range, just to see if there is more gain range available.

Not to derail the thread, but I had a circa 1998-99 PC monitor do this. It's too heavy to lug out, but I believe the streaks were blue.

In a CRT monitor (or a solid state TV), that kind of streaking affecting only one color is generally due to the driver transistor for that gun going into saturation. It's usually because that gun's emission is weak and somebody has cranked up the drive to compensate.