Ok I am bouncing between tinkering with adding a composite input and also still trying to dial in the color purity and convergence.

I am redoing the color purity and I am struggling to get an all red picture, note it has never been perfect yet. Is getting perfect color purity all a matter of mechanical adjustments of the yoke and convergence magnets? I can get an all red picture but the centering is way off. What else should I look for?

One other thing is I can get the purity better by playing with the horizontal hold which I guess moves moves an uncentered red screen back to center but then on restart the picture could not hold until I adjusted the horizontal back.

Also note the above purity adjustments I am trying are with the tuner, I have paused on the composite input for a bit.

Horizontal hold should not affect purity. You may be seeing the effect of mistiming the burst gate. Set H hold to mid range and leave it there.

Strong interaction of the purity rings and centering may mean the rings are at the wrong position on the tube neck. Look for an illustration of the tube neck components and try to match it.

Hard to give advice without being there to see what you're doing.

Are you using an all-red video, or killing the green and blue guns? A video could produce an impure red if the tint/hue control is not set perfectly. Killing the green and blue guns by grounding the G1s is the best way to be sure only the red gun is emitting.

I am using an all red signal via a setup DVD and then turning the blue and green guns all the way down.

That should be good.

Be sure purity rings are at the REAR.
Warm up set 1/2 hour.
Degaus CRT.
Slide yoke BACK.
Turn color all the way down & turn OFF any auto color switch.
WITHOUT signal turn down the G & B screen controls.
Turn UP the red g-2 til retrace lines then back off til they go away
Now you should have a red blob apx the center of screen.
Center the blob.
Slowly push yoke forward til the whole screen is RED.
Too far & you will loose the purity again.

NOTE unless you are short, to make these adjustments its MUCH easier
to lay across the set. Mirrors are a PIA & not as accurate.

73 Zeno:smoke:

Make sure you have the purity ring set for minimum effect to start. Can you post a pic of the components on the neck as they are currently?

When Zeno wrote "center the blob" that meant center the red blob by using the purity rings, not by using centering controls.

My apologies for the delayed reply, I completely missed seeing the replies here on page 4.

Ok so I am feeding in composite video from a DVD player into my RF converter. The feed is from a DVD titled TV Test Card/Video Pattern Generator DV. I have the green and blue screens turned down and am using the all red signal from the DVD player, note the video has a black + in the center and white arrows on each side.

See below for the results. I would say it is a bit better than I had before but I can not get the image centered nor does it completely fill the screen. If I try to center the image I can not get to an all red purity.

Note I can move the image over via the horizontal hold but then when I restart the TV the horizontal hold is lost and I have to bring it back to off center.

Let me know what you think, also if more pictures or a video would be helpful.

https://i.imgur.com/96ekb7X.jpg?1
https://i.imgur.com/gI41MUf.jpg?1
https://i.imgur.com/sLefxdD.jpg?1

More questions:

Did you take a picture of the position of all the neck components before replacing the picture tube?

Is the white device between the purity rings and the convergence yoke the centering control?

I did take some pictures before removing the old crt, see below for how the purity was adjusted. As for the installation I have the yoke, then the red/green/blue convergence assembly, and then the the blue lateral and purity control which is one part. Am I missing or forgot something?

I have been trying to both center the screen and get color purity by adjusting the purity magnets and sliding the yoke forward and back. Note sliding blue lateral and purity control forward and back provide some very minor effect.

https://i.imgur.com/Msgen9d.jpg?1

Um.. aren't the purity rings supposed to be located forward (front-ward) of the blue lateral? Might try reversing the assembly.

Nope rings are last on.

I was thinking blue lateral after I posted. It seems a peculiar design to have it attached to the purity rings and not the convergence assembly, but it is what it is.

When you adjust H centering, how are you doing it? Is there a centering control, or are you trying to fiddle with the yoke? Some sets (like my old Magnavox roundy) had no centering control and you just had to take what you got. The H sweep was wide enough to avoid black edges, but you could lose up to 20% or so of the picture.

As yours is not filling the screen, the problem may involve the H output, H drive/efficiency/linearity adjustment, H driver, etc.

old_tv_nut, thanks for the replies. It seems that I may have to compromise on color purity or centering. There is no specific centering control as I understand.

I can move the screen left to get it centered with the horizontal hold but then when I turn the TV off and back on the horizontal hold is lost. I will try again and see if I can find a combination of horizontal hold & horizontal efficiency that allows me to fill the screen and have good color purity. Are there any key component values that I could check or even change to provide some further range?

Is there an interaction with the vertical linearity, vertical hold, and height? Also there are controls for the pincushion amp, and pincushion phase, note Sams states the pincushion phase is factory set and seldom needs adjustment.

Compromising purity for anything else is not possible; you can only make it worse. So set the yoke and purity rings for best purity, and leave them there.
Don't use horizontal hold to adjust centering. This will affect the timing of the color burst gate and potentially make color unstable. Horizontal hold should be set to the center of the hold range.
Consult SAMS on adjustments in the horizontal sweep section. Note that any horizontal efficiency adjustment must be set so that the horizontal output tube doesn't draw excess current.
Use an Indianhead or similar test pattern with circles to check width and linearity. Use a crosshatch pattern to check pincushion amplitude.
Vertical and horizontal adjustments are generally independent of each other.
SAMS should give an indication of what order to do these various adjustments.

Your width problem could be due to weak tubes in the H sweep section (H driver, H output, damper).

Good luck!

Still fighting this set. After lots of attempts at getting the purity and convergence setup correctly I can get good color purity but am unable to get the picture to have good horizontal centering, I am left with unused screen on the right side. I can use the centering rings to center the screen but then cant get good color purity. I have checked the B+ and boost voltages all measure good also tried swapping the horizontal output and damper tubes but seen no improvement. This suggests that the issue is not a width problem.

In looking back at pictures the centering issue was not present before I swapped out the CRT, now to be fair I had not checked for purity on the old CRT so the issue may have been there, still could it be the new CRT? Also since installing the new CRT I ran into an issue with HOT high current, it was an intermit resistor that would measure ok on the bench but fail in operation. I resorted to shotgunning lots of parts, while I have checked and rechecked all part values I certainly could have made a mistake somewhere. Thoughts on any key components I should check that would allow the set to operate well but not have horizontal centering.

• Full PDF Schematic: https://drive.google.com/file/d/1Fda...ew?usp=sharing

I was browsing schematics and it looks like earlier RCA sets did have horizontal centering via a 10 ohm pot across taps on the flyback which then feed the yoke. Maybe something can be hacked in but I'm not up to that without good guidance.
https://i.imgur.com/oPZscVd.png.

I lost track of what all was tried in this thread.
Is the raster actually off center (no light in the black part if you turn up the brightness) or could the horizontal phase be off (raster is centered but the picture is phased to one side, black part of the screen lights up when you turn up brightness)?

Looking closely at your blue lateral magnet it looks like the wheel you turn should be at 12:00 and not where you have it currently. The blue gun is the top gun in the neck of the tube. I remember on Zenith lateral magnets that the rotating adjustment part was at the top of the neck on the jug.

old_tv_nut to you question, I don't know, I was thinking that the raster was shifted to the left. During setup it seemed that the raster as a whole was being moved to the left via the purity rings to get an all red screen. But maybe the right edge is just missing the picture and still receiving a black raster.
https://i.imgur.com/nQywj55.jpg?1

See the below video where I turned the brightness up and down, the image curves in as the brightness goes up. I can get the right edge of the screen to light up but I don't know is this raster or just light shining through?

• Short Video: https://imgur.com/ZPrGLCY

Just turn the brightness to max and you'll see if that area lights.

Edit: I didn't see the text below the picture at first.
It looks like there is a little bright strip on the right side and then full balck (no raster) (?)
If that is correct, the problem is not horizontal phase but raster shape and centering as you have been saying.

Second edit: Sorry i'm not awake! I looked at the video now and it's obvious the raster goes all the way to the right edge of the tube (and probably beyond) as the whole area lights up.
Once again, you need to go for best purity first and not change that, then see if you get the same effect (light all over the right side when you turn up brightness, but picture pulling to the left.) You may have two problems at once and need to not try fixing one by adjusting the other.

If the horizontal sync phase is the problem, suspect the phase detector X14 and the components around it.

If your scope is dual-trace, connect one probe to X11 (AGC gating pulse) and the other probe to the video detector output and see if the pulses line up and don't move with respect to each other with changes in video content etc. Make sure your scope is triggering on channel 1 only or channel 2 only.

also make sure X11 is good

old_tv_nut, thank you for the troubleshooting ideas, I am way into uncharted territory. I will start with checking components around X14 and X11. I do have a 2 channel scope but will have to pick up a second probe. Stay tuned and thanks again everyone for the advice.

In looking at replacement parts Sams notes that X14 can be replaced with the following:

• Sylvania ECG 113
• General Electric 6GC1
• International Rectifier DD04

Now in scanning Ebay I see both ECG 113 and ECG 133a, the descriptions states selenium and silicon respectively. Can I assume these are interchangeable and the silicon is likely the better choice?

https://i.imgur.com/MZoSWDM.jpghttps://i.imgur.com/XPkRf4A.jpg

If I had stumbled fresh onto seeing the screen shot in post# 60, the first thought woulda been "borderline-weak H output tube". And the first move would have been the "7 seconds off" test. That is, with the set running, turn it off for about 7 seconds, and back on. If the width is slow to fill back out, the tube may be borderline ('specially if it's been red-plating much). Whereas if the width comes back quick, the tube is obviously good.

It's a 'quick & dirty' little test that can also show up other borderline tubes. E.g., H oscillator, color oscillator, vert output, RF amp.

Nowadays shottkey is the best choice followed by silicon...garden variety 1N4007s (you'll need 2) are usable, but shottkeys will work better.

Yes, this could be it.

A circular test pattern like the Indianhead would show the bad horizontal linearity in this case (compression on the extreme right), but you might also be able to detect it with a crosshatch.

I just looked up 6LQ6 prices online - YIKES. Audiophiles have jacked the market up out of sight.

So early in my repairs I replaced the horizontal output tube and damper tube with what eBay claimed to be NOS tubes, plus the sellers noted they tested good too (vs just looking NOS). A few weeks ago I picked up spare tubes and swapped these out but did not see any improvement. I don’t have a tube tester so who knows, I could have bought weak tubes.

and yes, silly expensive.

We ran into quite a few borderline width cases always on rectangulars, using brand new H.out and damper tubes. Had to finally resort to putting a 82pf, 6KV disc ceramic cap across the damper (cathode to plate). This bumps the width out just a smidjin. Sometimes had to increase to 100 or 120 pf to get 'just enough' overscan.

The mod also has the effect of lowering H.out cathode current slightly (good). But it also reduces HV slightly, requiring bumping the HV adjust up a bit. So there's no 'free lunch'. The usable value for that cap is no higher than 120 pf.

Assume something like this should hold up to replace the horizontal AFC dual diodes: https://www.mouser.com/ProductDetail...R3IQl24Q%3D%3D

• Schottky Diode
• 3 amp
• 100 volt