Alternative Way of Adjusting G2s (25EC58)

[vol.2]

Originally Posted by 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.

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

[TinCanAlley]

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.

[TinCanAlley]

Originally Posted by 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).

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

Thanks!

[old_tv_nut]

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.

[TinCanAlley]

Originally Posted by old_tv_nut

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.

[TinCanAlley]

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?

[old_tv_nut]

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.

[TinCanAlley]

Originally Posted by old_tv_nut

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.

[TinCanAlley]

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.

[TinCanAlley]

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.

[old_tv_nut]

Does the problem shown in "More color change.jpg" also come and go when playing with the tint knob, or is it constant?

[TinCanAlley]

Originally Posted by old_tv_nut

Does the problem shown in "More color change.jpg" also come and go when playing with the tint knob, or is it constant?

No, what is seen there I believe was due to an incorrect ACP adjustment. When in align mode, the colors were rolling again and in the reds you could see the blue rolling through them and produce that blue blotch as seen in that pic. I wasn't able to get the rolling completely stopped, so I rotated the pot back and forth a number of times and was able to find a spot where the rolling was pretty much stopped. Since that adjustment I haven't seen the blue in red issue, but if it starts again I'm going to go over that board and clean the pots, etc.

I did manage to calibrate the set with the chromatic pots and I let the set run for a few hours. There was no change in tint, so I'm thinking that either the pot is bad, or maybe the wires need resoldering. I had to do that to the volume wires as they broke at the solder point from me taking them out and reinstalling a few times.

[TinCanAlley]

Well tint is changing again. After being on about 5 minutes or so, the tint moved towards the magenta side and pretty much stayed there. What I need to know is which module I should be looking at. The tint connects to the subcarrier and the chroma modules. The subcarrier is an NOS, not rebuilt, unit and the chroma is original to the set. I'm assuming one of these modules is faulty and as it warms up, the tint drifts. Happens to tint with user or chromatic adjusted pots.

Any help identifying the proper board would be appreciated. Otherwise I'll hunt down a replacement chroma board.

[vol.2]

Originally Posted by TinCanAlley

Any help identifying the proper board would be appreciated. Otherwise I'll hunt down a replacement chroma board.

Keep in mind that NOS stuff is still going to be like 50 years old and can therefore have bad components on them. Doubly so for used old boards.

It sometimes makes more sense to fix what you have because there's a baseline for it. Getting a new part means you could be jumping from one set of problems to another one.

[TinCanAlley]

When I first got the TV, recapping all the electrolytics improved image and resolved a number of issues. There is one board I did not touch, the video processing module. That one is under a metal shield/box. However, going over the modules in the SM I noticed that the board has 2 electrolytic caps on it. I think I'll replace them, just in case.

From what I can find, that module is first in the chain and can cause brightness and color issues.

Update.... Well I found, after posting this, that I had already purchased a new module back in 2013, but never installed it. It's not a remanufactured module and is the updated version. It has one capacitor, instead of two, and updated socket for the IC and less overall in terms of components. It's also the white board, not brown. I think I'll check the single capacitor on it and then install it.