Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 7 Old 09-15-10, 10:34 PM Thread Starter
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Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

As a former unregistered lurker, I want to give a shout out to lcaillo for his excellent and detailed feedback to posts. It's been very helpful.

I have a six year-old 42-inch 480i/480p/1080i HC-P4241W CRT Rear-Projection television from Samsung. It's been great, but I noticed some convergence issues on the left side of the screen, mainly with the red. it was most noticeable around text, so it showed up mainly when in the receiver guide.

After doing some research, I went into the manual convergence mode (mute 1 8 3) and adjusted the lines. This fixed the problem and this particular convergence issue is now gone.

Unfortunately however the Self Focus no longer works. The first question I have is whether the Self Focus is really worth it or if I should just forget about it and leave it off? I don't think it really did much as it didn't fix the convergence issue I had to begin with.

With the Self Focus not functional, I am concerned that the grids will gradually drift on their own, causing misalignment in previously good areas. I understand RPTVs are known to misalign themselves due to magnetic fields, which is why these "Self Focus" mechanisms exist. I'm curious to hear your thoughts on this.

I have read that if the grid is not perfectly center, the Self Focus sensors just won't be able to pick up the light sources. The grid is slightly off for all the colors, but only by a millimeter or two. I can adjust the red and green grids fairly easily, but I'm not sure if I should do this as I do not have a screen convergence jig. I have the service manual and read the measurements required, but they are very specific measurement figures (down to two decimal places in millimeters!), so I'm not sure if it's a good idea if I try to center the red and green grids without a specific jig.

Now the blue grid is a problem. In 1080i mode, the blue grid is slightly tilted to the right. I thought this might require a mechanical adjustment on the blue CRT or deflection yoke to fix, but when looking at the blue grid in 480i/p, it's almost perfectly level.

I could level the 1080i blue grid by doing fine adjustments (from the cross points and not line/grid moves), but seeing how I don't have a screen jig, it's probably not a good idea as I could make the lines slightly curved and no longer straight.

My question is why would the blue grid be tilted in 1080i mode but nearly level in 480i/p mode?

The other problem with the blue grid (in both modes) is that it's very hazy around the edges. It's only bright in the center of the screen, and even so, it's not as bright as the red and green grids. The other problem is that there is a haze around the grids, which I have now noticed is showing up quite clearly. I discovered the haziness of the blue grid a few days after doing the initial convergence adjustments (which were done to the red). Could the lack of Self Focus have caused the blue to become tilted and out of focus, or is this not related at all?

To sum it all up, venturing into the service convergence menu to adjust two red lines has led me to make discoveries of other issues and break a function (the self focus). I kind of regret messing with the convergence menu to begin with, although I am happy that I fixed the red convergence issue on the right side of the screen which was quite noticeable.

Now that I've discovered the haziness in the blue grid, I am now noticing a blue "glow" around the edges of dark/light objects when watching TV.

Any feedback would be greatly appreciated.

Nabil
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post #2 of 7 Old 09-17-10, 07:51 AM
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

The haze in the blue is likely bad coolant. The self-focus problem is the result of tinkering with the service mode without doing your homework. You need to read the service and/or training manuals to get the proper procedure for initializing the auto-convergence function when you leave the service mode. Each model may be different. Do not rely on generic advice that you pick up on the internet. Use the proper manual for your set and follow that procedure.

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post #3 of 7 Old 09-17-10, 07:37 PM Thread Starter
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

I have the service manual with me and read through it in detail. After doing any convergence adjustments, the self focus needs to be run in service mode, but this won't work unless the center horizontal and vertical lines are perfectly in the middle of the screen.

The grid to begin with, was not perfectly centered when I entered the convergence menu. I can center it, but I have a feeling it still won't fix the Self Focus as the blue grid is likely too faint to be picked up by the sensors. I guess the Self Focus was functioning based on presets from when the TV was brand new, with the convergence grid perfectly centered and the blue grid bright and sharp.

I forgot to mention earlier that in 480i/p mode, the Self Focus was actually creating a very noticeable blue shadow (besides the slight blue glow) around objects whenever it ran. I was able to get rid of this blue shadow by going into the 480i/p convergence menu, and simply saving the grid as is (without doing any adjustments). This got rid of the blue shadows, but disabled the Self Focus of course. I only noticed this later on as I very rarely use the TV in 480i/p mode (only when using the DVD player).

I had a bad feeling that it might be dirty coolant that's causing the blue glow. I guess I have to decide whether to live with it as is or fix it.
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post #4 of 7 Old 09-18-10, 03:05 AM
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

The coolant will only get worse and harder to deal with. It forms a hard crust on the back of the lens if you let it go too long.

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post #5 of 7 Old 09-18-10, 09:35 PM Thread Starter
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

Thanks for the feedback. Is it worth getting a repairman to replace the coolant or would it be better to get a new TV at this point?

I imagine this is a costly repair.
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post #6 of 7 Old 09-18-10, 11:02 PM
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

Call around and find out what they charge. The relative value of the repair vs replacement will depend on the cost and your priorities. Personally, I never was happy with the performance of these sets, even when I really tweak them to their best, so I would not put much money into one. If you have been happy with it, it may be worth doing, however.

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post #7 of 7 Old 09-18-10, 11:27 PM Thread Starter
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Re: Manually adjusted convergence in RPTV, Self Focus no longer works, Blue glow

When you say you've never been very happy with the performance of these sets, is that in regard to CRT RPTVs in general, or with these Samsung CRT RPTVs specifically?
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