re-aligning the geometry? - AVS Forum
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post #1 of 14 Old 03-28-2008, 11:34 AM - Thread Starter
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whats a good method to re-align the geometry on a mitsubishi wt-42313 or any TV I was trying to fix the overscan on my TV & now I get little wave effects in some areas need help this things owning me

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post #2 of 14 Old 03-28-2008, 02:08 PM
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While you can spot gross geometry problems by eye with a test signal, there is just no way to precisely correct minor errors that way. Back when CRT RPTVs were big, people used to make and sell patterns to put over your screen for geometry purposes. Your best bet is probably a measuring tape, string and some tape. Measure out where the strings need to be for proper alignment, stretch the string taut, tape the ends to the frame of your TV and then use the strings to get your geometry lined up. This method won't be as perfect as using a pattern, but it'll help you correct the major problems hopefully.
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post #3 of 14 Old 03-28-2008, 03:38 PM - Thread Starter
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Quote:
Originally Posted by sperron View Post

While you can spot gross geometry problems by eye with a test signal, there is just no way to precisely correct minor errors that way. Back when CRT RPTVs were big, people used to make and sell patterns to put over your screen for geometry purposes. Your best bet is probably a measuring tape, string and some tape. Measure out where the strings need to be for proper alignment, stretch the string taut, tape the ends to the frame of your TV and then use the strings to get your geometry lined up. This method won't be as perfect as using a patern, but it'll help you correct the major problems hopefully.

ok cool sperron how much spacing should I give each box ?

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post #4 of 14 Old 03-28-2008, 04:26 PM
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No one can really give you an answer on that. It would depend on how large your TV is and exactly how much overscan you are aiming for. You'll have to do the math yourself. Look at your test pattern and see how many boxes the pattern has vertically and horrizontally and use these to divide by the height and width of your screen.

If your main goal is just to straighten out the areas you see problems in, you could always just use the existing test pattern lines and just run a string across the problem area so you atleast have a good reference. It just depends on how far you want to take things. A full and total geometry and convergence can take a very long time. You have to do a full multipoint converegence on green and then use green to do red, then again for blue. You might be looking at most of an afternoon staring at a grid if you go all out.

You'll probably want to do some research on converging Mitsubishis before you do it to make sure you don't do all that work and somehow lose it. One of the best sources for technical info on Mitsubishi TVs is www.***************.com. Go to their forums and you'll find the Mitsubishi section. I haven't spent much time there in a couple years, but they used to have quite a few Mitsubishi experts around there if you have any questions.
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post #5 of 14 Old 03-29-2008, 04:56 AM
 
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Personally, I have had no problem with the geometry/overscan patterns on AVIA'99 and DVE'03.

While DVD players can vary in their ability to process BtB and WtW, there should be little variation in geometry patterns up to 1%.

Company we have had over have remarked about there being "something different" about our TVs. Fox News and MSNBC, in addition to the tickers seen for the past 7 years, have stationary items in 3 of 4 corners. Visitors said they "weren't aware" of the items, and were surprised to be "actually able to read" the news tickers! That's with the 4% overscan I was able to manage without showing that *weird* stuff you see on a broadcast monitor set to overscan mode. My question to them is - What kind of televisions have you been watching the news on; is the o.s. that bad?

And we have flat direct-view screens. Imagine using strings & tape on a curved one??
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post #6 of 14 Old 03-29-2008, 05:39 PM
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+1 what Sperron said. Geometry work on CRT RPTVs is labor- and time-intensive, but the results are worth it.

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post #7 of 14 Old 03-31-2008, 03:06 PM
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I'm blown away at the Overscan on Vizio's Coming from my Westinghouse LCDs and Samsung DLP's. Seems to be the worst on 42 inch displays.

But to the geometry issue at hand.... Geometry Test patterns are pretty easy to make. The best choice is generally to create a 50% Grey back ground, and then put two lines next to each other 75% (light Grey) and 25% (dark Grey) Start with some large squares evenly spaced and drop to smaller and smaller squares. It is important that your background it 50% and the the two lines you are presetning your grid differ from 50% by the same amount. You can use 0% and 100% but I try to avoid extremes as how hard you are driving a display often effects it's accuracy, so unless you are noticing "Credit Warp" or "Star Wiggle" you are better to tune towards the middle rather than the edge.
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post #8 of 14 Old 03-31-2008, 04:34 PM
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I'm just starting to get into re-aligning my geometry on my Mitsubishi TV. I've done most of it by eye so far.

Anyways, here's an idea I just thought of (but haven't tested yet). What about trying one of those laser levelers. Little square things with the little bubble in the water to make sure it's perfect level that shoot a laser across a surface.

That will get you as close to perfectly straight as I can think of. You will still have to do the measurements to space them properly, but the lines will be straight.
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post #9 of 14 Old 03-31-2008, 06:13 PM
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Quote:
Originally Posted by siege911 View Post

I'm just starting to get into re-aligning my geometry on my Mitsubishi TV. I've done most of it by eye so far.

Anyways, here's an idea I just thought of (but haven't tested yet). What about trying one of those laser levelers. Little square things with the little bubble in the water to make sure it's perfect level that shoot a laser across a surface.

That will get you as close to perfectly straight as I can think of. You will still have to do the measurements to space them properly, but the lines will be straight.


The TV would also have to be levelled in that case, else you would introduce rotation. Probably simpler/easier just to use the strings and measurement method. That way you are squaring the lines with the screen edges.

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post #10 of 14 Old 03-31-2008, 06:54 PM
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i suggest you do some more reading BEFORE DOING ANYTHING ELSE.

1. Im guessing you pulled your overscan in too much. Your Mits needs at least 4 %. When you pull the overscan down too low you can cause extreme geometry errors.

2. You need to use a convergence pattern (or white patterned grid) on a black back ground for adjusting geometry. This can be used in conjunction with the built in convergence grids.

3. a laser line level is a very good idea. So are strings.

4. BECAREFUL as it is very easy to damage a crt display by obsessing over geometry lines. These white lines can cause burn in relatively quickly.

Good luck!!

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Lead THX Video Standards Instructor
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post #11 of 14 Old 03-31-2008, 08:53 PM
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Quote:
Originally Posted by Rolls-Royce View Post

The TV would also have to be levelled in that case, else you would introduce rotation. Probably simpler/easier just to use the strings and measurement method. That way you are squaring the lines with the screen edges.

I tried the string thing myself and I found that it always hung down slightly in the middle. If I tried to pull it tightly, I ended up pulling it out of the tape. I'm sure I didn't have the perfect string or tape, but it was still annoying.
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post #12 of 14 Old 04-01-2008, 09:36 AM
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Quote:
Originally Posted by siege911 View Post

I tried the string thing myself and I found that it always hung down slightly in the middle. If I tried to pull it tightly, I ended up pulling it out of the tape. I'm sure I didn't have the perfect string or tape, but it was still annoying.

I rethought what you were saying. As long as you were measuring on both sides of the screen and then using the laser to establish the line between them, you wouldn't have to level the set. If, however, you only measured one side and then used the laser's level bubble to set where the beam went, the set would also have to be leveled. The main drawback to using the laser level would be if you had to adjust more than one line at a time. There are controls that shrink and expand certain portions of the picture just like playing an accordion (I forget the name of this control) so you can do a rough lineup of the gridlines before doing point-by-point adjustment, and you really need a template or multiple strings up to do it.

AEC Print Shop in Knoxville, TN used to produce geometry templates on heavy Mylar for different models of Mitsubishi CRT RPTVs. A member of another forum I belong to created them in AutoCad and sent the files to AEC for plotting. While not cheap, they were less expensive than the Mits factory templates and easier to use than the string method. That's where I got mine several years ago. They may still be able to make the templates, if you want to contact them about it.

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post #13 of 14 Old 04-02-2008, 05:47 AM - Thread Starter
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ok so made a template out of my protective screen because I don't use it but I'm getting some wave effects at the very top & bottom of my screen is there a way to completely get rid of it

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post #14 of 14 Old 04-03-2008, 10:08 PM
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Print a grid on a Transparency. Or Ruler and Sharpy on a Transparency.

Another favorite trick...

My camcorder will put a 4x3 grid on its display, so I created a slate that had that same grid for the Display, and you just adjust the zoom to match the size of the grid on the screen.
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