Alternative Way of Adjusting G2s (25EC58)

[TinCanAlley]

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.

[vol.2]

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.

[Electronic M]

Originally Posted by vol.2

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..

[vol.2]

Originally Posted by Electronic M

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.

[TinCanAlley]

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?

[Electronic M]

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.

[TinCanAlley]

Originally Posted by Electronic M

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.

[vol.2]

Originally Posted by TinCanAlley

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.

[vol.2]

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.

[TinCanAlley]

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.

[old_tv_nut]

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.

[Electronic M]

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.

[TinCanAlley]

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.

[TinCanAlley]

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.

[old_tv_nut]

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).