Alternative Way of Adjusting G2s (25EC58)
 

After cleaning the setup switch I am now able to get a line on the screen for blue with 3/4 turn, but not for red or green. If I go back to normal mode with an image in B/W (color turned down and brightness half way) I can see each color as I turn the controls. Color starts appearing after about 1/4 turn. I adjusted until I got a decent grey scale image. From there I adjusted the taps to remove the slight red in the light areas.

While this has produced a good image and color, I don't think it's the best for the tube if I don't have them set right. I'm wondering if there is a better way? Voltage level?

I'm not sure why the other two G2s can't produce a line. When I last checked the tube it tested good. Should I test it again as it's been 12 years.

The factory recommended manner of adjustment are for the most repeatable and stable mode of adjusting it, but cannot be the only way. I have one TV where the red gun are only a bit weaker that others, and I simply adjusted with a B&W image at low bright settings, and repeated for low light scene/image with normal bright position of usage. Worked like a charm. Only a little deviation from the original positions. A more distance from original adjustment means weak CRT or some kind of issue in the circuits.

It's been at least a couple of years since I messed with grey scale on a CCII. Generally on Deltagun CRTs the instructions will say to minimize brightness, flip service switch and turn down G2 controls. If one or more guns doesn't produce a line at max G2 increase bias or brightness range pot to until dark guns produce light at max G2. if neither pot/switch exists in circuit (they aren't always in a convenient/obvious location so check schematic) advancing brightness is allowable. Once all are able to make a dim line bring up red to barely visible, bring up green to make the line yellow, bring up blue to make line white, return service switch and brightness to normal positions and if necessary touch up color drive pots for good white balance.

I know it doesn't take much advancement of the G2s to bring up color in a B&W image, so I'm assuming the CRT is working well. Why that same advancement doesn't produce a line is beyond me.

The only adjustment related to brightness I can find is the Brightness Limiter (other than the brightness user control). I guess I can do the adjustment procedure as it might have drifted from what I did 12 years ago.

I am trying my best to trace the setup switch in the schematics, but I think in setup, it disables brightness control. When I bring up the blue line, advancing the brightness control has no affect on its intensity.

Okay, I did trace the setup switch. It seems when switched, and I'm over simplifying this because I know there are other changes such as vertical, it disconnects the contrast and brightness circuits and connects the red video output to the brightness limiter circuit. I'm attaching a couple small images of the two circuits it connects with a red line showing the setup path.

A tiny tweak of G2 should adjust relative color level a bit on normal viewing. It's absolutely possible to still have that effect on a normal picture but no setup line...that happens when the gun bias voltages (cathode, G1,G2) are wrong or when the CRT is weak. If the cathode to grid voltage difference has the grid too negative or G2 isn't able to reach the B+ boost voltage feeding the one end, or the HV is below rated level that all could cause it.

I'm not sure how the schematic snippits you show relate to the service switch. You show the brightness limiter hooked to the Red video transistor but it probably interacts with all 3 color video transistors through paths that can't be fully seen in the snippits.

If you have a DMM and a CRT tester that's known working check the CRT and check the voltages feeding it. Maybe write them down and report back on the voltages VS schematic.

I used to have a Zenith 4-tube hybrid (basically a CCII flat chassis chassis but with tube horizontal sweep) with a bad CRT previous owner got it used in the mid 70s and it was his main daily watcher TV until 4 years ago. Two of the guns couldn't produce a line and I think I just turned off color and did what I could with color at minimum and a full screen grey scale pattern. It looked ok as long as adjusted several minutes after warm up after gun emission drift stopped.

The service switch isn't a rare part and I have seen dead ones completely kill raster in both positions...I just replaced the switch to cure the problem.

The parts of the schematics I showed how the setup switch connected those two circuits together. I'm assuming the switch when connected to the brightness circuit kills the brightness control and on the video side, I don't know what it does to that circuit. I could post the entire schematic, but with the size limitation here, it wouldn't be very readable.

I do have a B&K 470 with correct socket. I'll test the tube. I'll also get my small clip-ons for my DMM and test voltages. I'm assuming the best place to do that is directly to the CRT pins?

Just tube through entire test and it is in great shape. So now it's on to voltage testing. I'll scan back through past posts as I recall doing something similar back in 2013. Will be interesting to see what I get now compared to back then.

Just went over past posts from 2013 and found one I completely forgot about and it was never answered (the thread stopped after one other post). Guess I gave up, but now that I'm back in fix it mood, I want to continue.

I hope this link works, if not I'll copy and paste.

https://videokarma.org/showpost.php?...&postcount=188

This discovery was just verified today. I still can produce the lines if the taps are removed from the video drivers. Gotta be something to that.

I will give this a try as testing the CRT puts it as being good and I don't want to push it harder than it should be so I lasts as long as possible.

So when I do this I should turn the brightness control down to a very low level, but the image should still be visible for adjusting. Contrast matter? Then once I adjust for a good grayscale, I turn up the brightness to a normal level and readjust the guns.

I've done it with just a black screen - like you sometimes get with a modulator with nothing hooked to the input, or a DVD player turned on, but with no disc in it -- The black will look a little too red, green, or blue depending on which is set too high. With this method you can set the controls too low though, so you want to start with the controls a little high, then turn them down till just when the black screen stops looking too red, green or blue, but no lower.

Ideally, the lowest light setting is a perfect grey, and the whitest bright setting is pure white.

In theory, you're tracking will be right on if you do that. In reality, the demodulation is going to play a role in between, so if that's off, then the stuff in between is going to be off, then color balancing isn't going to fix it.

Always good practice to turn color to minimum during grey scale adjustment. If color demodulation adds significant tint where it shouldn't at normal color level then you probably need to service the demodulator.

I was hoping to use a purely black and white movie for adjustment, but when checking them on my OLED, I noticed that all the ones I wanted to use had some sepia tone. Guess I'll just use one and the color control off would have to be good enough.

I'll start with a black and white movie, color control off, brightness down and G2s 50%. I'll adjust for grayscale by backing them off. If this doesn't provide a bright enough image, I'll do it again with the G2s starting above 50%.

The color control is very touchy. It is totally saturated at less than a quarter turn. I don't know if that's normal or something is out of calibration. I find if sometimes skin tones look blotchy as if color in certain spots is not the same intensity as others. Notice it quite a bit in color text and graphics, but also on faces. I ignored this as I figured it was due to my not having the grayscale set properly, but it could be in one of the modules.

Typically, a pattern generator is the thing.

If you own a Nintendo Wii, you can do an easy (and reversible) soft mod on it to allow homebrew apps, and get a copy of 240p test suite on it.

The Wii is really good for this as it outputs composite, s video and component.

240p test suite also exists for many other systems, but they obviously require you buy a cartridge version which is more expensive.

Another way to do it is to get a VGA to composite adapter and hook up a PC to it with a VGA output.

Yet another option is to find a test pattern DVD image online, burn it to a DVD player, and play the DVD.

You can of course just go buy a pattern generator, but a good working one is starting to get expensive. When I was buying them, they were cheap.

Don't buy a Heathkit one, they are flakey. I've gone through 2 of them and the ICs both died.

I've been using 3 different Heathkits for several years. They aren't the best, but I've never had a dead IC....I have seen plenty of flakey IC sockets though. Usually reseating ICs cures socket issues I often do that with it running into a TV so I can see what is going on..

The heathkits I have don't have sockets for the ICs. They just went bad, and rebuilding them with new passive components made no difference. The ICs will work for about 30 seconds and then fritz out and fail. Spraying them with cold spray momentarily restores function. After having two of the crap out in the same way, I decided not to buy NOS ICs for them because I felt like they are too likely to die.

I just got a good BK unit and that never has any trouble. That and the Wii with 240p test suite are serving me well now.

I have a leader LCG-396. Should I bring up the color bars or white screen and press the chroma button to remove color signal?

While we're on the subject of pattern generators, I was going to use it to redo my convergence, but have a quick question about the center screen magnets. If I understand it correctly, the red and green static convergence magnets move them diagonally and each one is a different direction so you go back and forth until they cross paths just right to converge. Should I move the blue out of center so I can align the red and green, then move the blue into position? The blue moves horizontally and vertically through separate controls. If I get it right I should have a decent white dot on the screen. Then I use the convergence controls with the grid pattern for dynamic adjustments and keep an eye on the center and readjust the static as needed?

The chroma button on the TV doesn't turn chroma off. It swaps the user brightness, contrast, color and hue pots, for a second hidden set of pots and sets the auto color circuit in the demodulator....The basic idea was for dummy and for people with kids who like to mess with the user picture pots you can just push a button and get back to a normal picture. The presets are usually hidden inside the pot shafts and can be adjusted by pulling the user knob and sticking a long skinny flathead screwdriver down the hollow shaft.

You want to adjust the RG static magnets so the colors overlap at the center like you say. Normally you do RG then converge B over them. I've heard of people moving the blue away but in practice there's often enough interaction that RG needs touched up if you do. What I do is have blue close unplug the cathode wire to kill blue (turning down G2, or using a 100K resistor to mute a gun are also options) convergence RF then turn blue back on and converge it with RG.

Not the chromatic button the set, the chroma button on the pattern generator. Pressing is supposed to remove any color signal from the generator, so the set receives a pure B&W signal.

As long as there's no color, it should be fine. The pattern generator should also have black and white screens to use.

I have never checked before, but you should be able to verify that it's just sync by scoping the output of the pattern generator.

Do you see the oscillations in this diagram during scan time?

For there to be color in the image, you would see those during scan time, but black and white will be just flat bars at low and high brightness levels.

Look on the left and right sides of scan time, you will see that the white is high up, but flat, and the black is down low and flat. The colors all have characteristic oscillations with a phase relationship to the color burst.

If the output of your pattern generator is flat during scan time, they you're golden.

https://i.imgur.com/xXIgCPq.png

Well I did a boneheaded thing. I decided to make all the adjustments noted in the SM before I got to the convergence as it says to do all the miscellaneous adjustments first. Things were going well until I went to adjust the ACC. I followed the instructions precisely, but the reactions weren't as expected. I was supposed to measure voltage for one point, then put the set into align mode and jumper two other points. From there I was supposed to read the voltage, then remove the jumper and adjust the ACC until the voltage matched the first value. I turned the ACC pot, but nothing happened. I rotated it back and forth a few times incase it was dirty. Still nothing. I forgot the mark the starting position, so I had to guess.

Anyway, I went back to the manual and I verified all the steps and ACC pot location. That's went I noticed the subcarrier board is different than the one I have installed. Mine is the updated board, so instead of the 9-27 I have the 9-69. Looking closer at that board, the ACC and APC are reversed from the 9-27. So that entire time I was messing with the APC. Looking over that adjustment, it says after adjustment I need to scope the RGB points and look for properly keyed rainbow waveforms. I'm assuming they are referencing the waveform examples on the schematic for those test points? If so, I need to get out my scope.

So what exactly does the APC do? It doesn't explain the function, just how to adjust and check. Also, what does the ACC do and how would I know if it was out of adjustment.

APC adjusts for proper free-running color oscillator frequency. "...minimum movement of color..." means the set's color oscillator frequency is close to the color burst frequency coming from the test generator.

The ACC and APC have absolutely nothing to do with convergence. They are color demodulator adjustments and unless you have no-color, no color sync, bad tint range or some of the test pattern colors are wrong when others are right you normally don't need/want to touch those service controls.

So should I put up color bars and adjust the APC as the manual states. Do I need to verify with the scope, or is visual enough?

I did the adjustments because the SM notes on certain settings that don't normally need adjustment after done by the factory. These didn't state that, so I thought they were normal adjustments. I wanted the ACC as I thought it was going to fix an issue I have now. The pattern generator doesn't come up in color. If I adjust the tuner, I can see it trying to bring up the color, but goes back to black and white. When I connect the DVD player via RF, I have to adjust the tuner and get it to the very edge of a strong signal to get color to show. Too far and it goes away, so back and forth I adjust.

I did the static convergence and then dynamic and must note that the sides where I couldn't converge the blue before, this time I was able. So while not perfect, the convergence is better than before and much less noticeable while watching. I think I'll leave as is and finish up the grayscale.

Well I'm making good progress. Image is looking pretty good after convergence, etc. I am attaching a pic. The pic doesn't really do the image justice as I'm still trying to figure out the best settings for my camera on my phone. It is washing out the colors a bit, especially facial tones.

If anyone knows the best settings on a samsung phone, let me know. I set shutter for 1/60 and and ISO to 800.

You should set shutter to 1/30 to capture a full frame (2 fields). This will make the picture even brighter, so reduce the ISO and/or use a smaller aperture (higher f/number).

I think that looks really good. Especially if it looks better in person.

I got things just about where I think look best. Don't want to try to make it better as I don't think I can and I'm sure I'll just mess up what I now have. I do have two issues I cannot figure out and it's starting to really bug me. I'll do my best to describe and attach a few pics with the best examples I could find. Still working on best camera settings, but I'm pretty close.

First issue is with color in faces, but very pronounced in credit and titles. The skin tone isn't always even across faces. Might have a normal skin tone, but one section of the face is a little more grayish in tone. Titles and text that are colors such as orange, yellow and such have faded color in the center and close to normal color on the edges.

Second issue is this odd issue with certain reds in the image that get a blue tinge to sections. For instance, I was watching a show and the person was wearing a red shirt. Depending on camera angle, sections of the red shirt had blue. Then another show the person was wearing a read hat and it had a blue tinge to the whole top of the hat, but other camera angles it showed pretty much as it should.

Not sure where these issues come from, but I'm guessing they are the same thing and I just need to find, fix and/or adjust something. It didn't do this before all the adjustments I made, so I either caused it or something else was off before and I never noticed it.

Also attaching pic with white lettering to show how decent the convergence is. You might also notice the issue with facial tones in it as well.

That did the trick! Depending on brightness, I have to readjust the ISO, but the pics are so much better.

Thanks!

I was going to mention IF and color section alignment until I saw the color tinge photo with the red hat having red on all edges including top and bottom and blue in the center.
Now I'm scratching my head as to what could possibly do this. Misalignment should affect only left and right edges of an object, not top and bottom.

If you look at the background of that image, you'll notice someone with a red shirt and it's not affected. While I seem to only notice this on red sections, it's not all red sections. Also not sure if this issue is related to the text issue.

I think it might be in the tuner? Could that be possible?

I used a calibration DVD and got the color, tint, brightness and contrast dialed in and the test footage looked great. I then put in a regular DVD and it looked great for a bit, then the image got grainy and the colors changed to a more purple hue. I changed channels and back and the image was better, but the hue was still off. I went to another channel, turned of AFT and tuned that one into channel 3 and it was much better. But after a few minutes the color got over saturated until I changed the channel again. I decided it was time to turn it off until I can figure out where to start looking.

Would the ACC and ACG have any connection? The ACG is the one I messed with by mistake. Or maybe color killer?

OK, you may have two problems combining to give this effect.
The change with fine tuning, channel change back and forth, could be a tuner issue. Then, as the change in tuning affects the color level, it could be some kind of overload in the color circuits related to the ACG.

First, get the fine tuning right. Turn off the AFT, and set the fine tuning manually. turning one way should make the picture blurrier and reduce the color signal. Turning the other way should make the color signal stronger. There may be little visible change in the color strength due to the internal automatic color control (ACC), but eventually on this end of the adjustment, the picture will show "wormy" interference that moves with the sound content. When you see the sound interference, turn back the fine tuning until the interference disappears. Once the fine tuning is correct, try adjusting the ACG.

I adjusted the ACG and ACC while I was there. Both set as per SM.

I'm attaching two pics. First one is after adjusting the tuner, ACC and ACG. The second is about 5 minutes afterwards. I'm starting to think it's somewhere tint is coming from. If I adjust tint, I get it back to what it was before. I tapped the pot and knob, but couldn't get a reaction in the tint, so I'm kind of certain it's not the pot.

Added one more and it again shows the blue over the red, although the red isn't red anymore.

Just noticed something. When I was adjusting the ACC, it said to short two points, read voltage, remove short and adjust ACC to same voltage as when shorted. I did this and the voltage was 16.8V. I've been going over the schematics and it shows the ACC points on the Sub Carrier Regen as being 8.6V to and from the Chroma module. The voltage I measured was twice as much, but other than the schematic, I can't find anything about voltage level for the ACC and whether it goes up or down from the voltage in the schematic.

One more update.....

I put up the color bars again and flipped the align switch. The colors were rolling through the bars again. I readjusted the ACG and found there are three spots where the rolling slows down and reverses. I picked another spot and went back and forth to get the rolling to stop, for the most part. I readjusted color and tint and got a great looking image.

Five minutes later, the tint had changed again to the purple side. I pulled and pushed the tint knob and it went back to normal. I find it had to believe the pot is bad as it is smooth changing the tint when rotating. Nothing odd happens when rotating it, so I don't know if pulling and pushing it did anything and I just got lucky. I'm going to press the chromatic button and adjust the inner pot and see if that one can keep tint setting.

The blue that showed up in the red, I saw the same thing when the color bars were rolling while adjusting the ACG. So I'm assuming that is the cause of it. I'm going to get out the scope tomorrow and check the waveforms as noted in the SM. Hopefully that will give some insight.

If I can just fix this issue, all will be well. I am very happy with the image when it stays adjusted.