Alternative Way of Adjusting G2s (25EC58)

[TinCanAlley]

Never mind, figured it out. I backed the G2 for green off until the grayscale pattern looked as good as I could get it. Then backed the red off just a tad and now it looks great. I tested it with going full brightness as that seems to highlight the color that's up too high.

Plus side, the issue with blacks in dim scenes is much improved and the transition between scenes no long displays a dim greenish gray screen and seems to stay pretty much black. Guess many of my issues, beyond hardware, is user error.

[vol.2]

Originally Posted by TinCanAlley

Never mind, figured it out. I backed the G2 for green off until the grayscale pattern looked as good as I could get it. Then backed the red off just a tad and now it looks great. I tested it with going full brightness as that seems to highlight the color that's up too high.

Bias/Background are going to primarily effect the low light color balance.

Drive is going to primarily effect the high light color balance.

There is absolutely interactivity between the two, but each is designed to have a greater effect on the color balance at their own brightness levels.

You want to correct for the low light color balance with the Bias/Background controls and correct for the brightest white color balance with the Drive controls.

However, because there is interactivity, you have to go back and forth between the two. Correct the grey at 20 IRE (fairly dark grey) with the Background controls, then display 100 IRE white (brightest white) and color correct with the Drive controls. Each correction will knock the other one out a little bit. The goal is to go back and forth until you reach the point where they are as even as possible from darkest to brightest.

So when you said this "I tested it with going full brightness as that seems to highlight the color that's up too high."

You don't want to turn up the brightness until you get a white raster and then try to color balance with the background controls. If that's what you are doing.

The idea is to be in a completely pitch black room and just barely turn the brightness up so you can see a dark grey raster, and then make that as perfect as you can get it with the backgrounds, without turning up the brightness. Then you switch to bright white and do the Drives, switch back, rinse repeat.

This often involves covering windows with cardboard or blankets to get the room dark enough and using flashlights to locate adjustment pots.

[TinCanAlley]

I did it in a dim room, but will do again at night to get it pitch black.

I did notice something when doing the G2s. I turned them all down, but the grayscale pattern I had up was tinted green. Is that supposed to happen? The green was pretty dark and when raising the green G2, it got a brighter green. Once I got that, I brought up the red til it was pretty much yellow and then the blue til it looked like a grayscale. I went back and forth with them until I saw no colors in the gray areas. From there I took the red tap from Hi to Med and the whites lost the red tint. So now the white are white and the grays are gray.

I find that when I adjust the controls according to the calibration DVD, it is too dim for normal viewing, so I adjust by eye from there. The DVD worked on a Toshiba 50" projection back in 2000 and a 65" projection in 2002. It also worked on all flatscreens, but I guess it wasn't designed for anything older.

I had the darn convergence pretty damn near perfect, but the center dot pattern showed it was off, so I did the center convergence and tried to touch up the rest. Didn't go as planned and now I have more areas with poor convergence. I guess the center convergence had a bigger effect on overall convergence than I thought it would. I would have left it as it was had I known.

I'll let you know how it goes when I do it in a completely dark room.

[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.

[vol.2]

Originally Posted by TinCanAlley

I think I'll check the single capacitor on it and then install it.

You might want to do a quick check on the resistors while you are at it.

Generally speaking, the resistors should be their value or lower when in circuit because any additional paths that they might follow in parallel to their position in the circuit will only bring the total resistance down, not up.

So if you check a resistor and it is either open or it's resistance is higher than the value on the case, you should remove one leg from the circuit and give it a real test.

It's also a good idea to (if possible) identify places in the circuit where there should be ground (zero volts) and a power rail, and make sure those places are not a short.

[TinCanAlley]

Originally Posted by vol.2

You might want to do a quick check on the resistors while you are at it.

Generally speaking, the resistors should be their value or lower when in circuit because any additional paths that they might follow in parallel to their position in the circuit will only bring the total resistance down, not up.

So if you check a resistor and it is either open or it's resistance is higher than the value on the case, you should remove one leg from the circuit and give it a real test.

It's also a good idea to (if possible) identify places in the circuit where there should be ground (zero volts) and a power rail, and make sure those places are not a short.

I can do that.

Any idea which board could alter tint? I see it on the schematic at the subcarrier and going to the chroma. Is it the subcarrier altering or is the chroma also able to alter it if something is wrong on the board?

I think I'm also going to pull each board, deoxit all the contacts on chassis and boards. I also noticed that when I look at pics of the chassis when I first got it, each board had 2 blue tubes on unused pins. No doubt used to secure the boards, but are these a real necessity or more for shipping? I really can't remember where I put them as I didn't put them back on the modules.

[vol.2]

Originally Posted by TinCanAlley

I can do that.

Any idea which board could alter tint? I see it on the schematic at the subcarrier and going to the chroma. Is it the subcarrier altering or is the chroma also able to alter it if something is wrong on the board?

I think I'm also going to pull each board, deoxit all the contacts on chassis and boards. I also noticed that when I look at pics of the chassis when I first got it, each board had 2 blue tubes on unused pins. No doubt used to secure the boards, but are these a real necessity or more for shipping? I really can't remember where I put them as I didn't put them back on the modules.

Again, I'm not really that familiar with these sets to the point I can offer a lot of specific advice on them.

Someone else will have to comment on which board does what.

I definitely agree with the idea of cleaning board edge contacts though. That can solve a lot of problems.

A related thing to check is the solder joints on any connectors that get stress. If you have edge contacts that slide into connectors, those connectors will be prone to cracked solder joints, and that is a common cause of intermittent issues because they can make good contact until they heat up, and then the heat causes things to warp and push apart and issues start to show up.

It's not a slam-dunk, but it is a common kind of fault and worth just reflowing.

If I'm working on an old set (regardless of the make), I will generally do three things before I bother even turning on. I check and replace any bad electrolytics, I use contact cleaner and fader lube on every contact, switch, pot, fader, jack on the set, and I reflow every single connector, socket or large heavy component (like a transformer) on the PCB.

My time is too valuable to chase my tail over a cracked solder joint if you know what I mean.

[TinCanAlley]

Originally Posted by vol.2

Again, I'm not really that familiar with these sets to the point I can offer a lot of specific advice on them.

Someone else will have to comment on which board does what.

I definitely agree with the idea of cleaning board edge contacts though. That can solve a lot of problems.

A related thing to check is the solder joints on any connectors that get stress. If you have edge contacts that slide into connectors, those connectors will be prone to cracked solder joints, and that is a common cause of intermittent issues because they can make good contact until they heat up, and then the heat causes things to warp and push apart and issues start to show up.

It's not a slam-dunk, but it is a common kind of fault and worth just reflowing.

If I'm working on an old set (regardless of the make), I will generally do three things before I bother even turning on. I check and replace any bad electrolytics, I use contact cleaner and fader lube on every contact, switch, pot, fader, jack on the set, and I reflow every single connector, socket or large heavy component (like a transformer) on the PCB.

My time is too valuable to chase my tail over a cracked solder joint if you know what I mean.

I'm going to remove all the boards and clean all contacts and reseat. Will also check all components on the boards that handle color. The schematics show the tint control connected to the subcarrier, but if the correct setting hits that board and is then sent to the chroma board, it could change if that board has issues.