Hitachi overscan & geometry - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 8 Old 09-09-2002, 02:24 PM - Thread Starter
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I have the 65swx. I would like to get my overscan from about 6% on the sides down to about 4%. The top and bottom is at 4%. I now where the knobs are to adjust overscan and I know that they are sensitive. Are there other steps I need to perform before doing overscan? How badly will this throw off the green convergence grid? I'm trying to figure out how extensive a procedure this will be.


Also I have a concave look to the picture. Like looking at the inside of a bowl. I have already straightened out some of the green convergence lines, but it still has this effect especially on the bottom when viewing from the side. It is the same effect you get if you were to push in on the protective screen and you can see how it distorts the picture.

Are there any adjustments in the service mode that allows me to change something like that? I do have a 61swx service manual. But I can"t seem to find anything that definitively relates to this.

One thing about the Mits they are easier to tweak I remember there being an area in the Mits where you can change the size, shape, etc. of the convergence grids.

As much as I hate to exchange this set, I may be forced to if this is an unfixable problem. I worry what the next set will be like. I went through that with the 61swx and the very first set turned out to be the best. But I would rather exchange it than to have it serviced, I've been that route too. The service techs know less than the people within these forums.

P.S. Mfusick I'll be expecting to see a post from you unless your wife hasn't given back your keyboard!
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post #2 of 8 Old 09-10-2002, 06:12 AM
 
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Quote:
Originally posted by colour

P.S. Mfusick I'll be expecting to see a post from you unless your wife hasn't given back your keyboard!
It's ok Dude,

I stole a really old and musty keyboard from the basement. :) Serious! It types so slloooowwww.... cause the keys stick:mad:

For Hitachi overscan I have not done the 20B model yet myself. When a freind or family member buys one, I am sure that I will get the chance.

If it's the same as the UWX adn SWX 10B models it should be easy though.

Heres a picture:

http://pages.sbcglobal.net/happyfunb...lectronics.JPG

Basically you turn those screws slightly. The changes you make should be apparent on the screen, and you'll figure it out once you do it. The procedure is very straight forward. I would put in AVIA and put on the OVERSCAN test screen when adjusting. Thats what we did, it worked perfect.

But, after OVERSCAN I needed t re-do my convergence which I had just done before the overscan, I had t do it all over again so I would not spend tons of time on the convergence before you adjust the OVERSCAN.

3-4% all the way around is great. Less than 2-3% and Magic focus might not work correctly.

There are controls in the service menu to control BOW and Pitch which would fix you concave effect you talk about.

All of your problems can be calibrated out, and your picture quality could rise far above "out of the box" status if you wanted to learn to do it.

Swapping tv's will always leave you with "out of the box" levels no matter what. Personally, I demand a little more.

Send me a Private message or instant message and I can share with you some tips from my service manual. I don't have the 20B service manual yet.

If you need more help let me know.... Gotta run for now..


-MIKE
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post #3 of 8 Old 09-10-2002, 06:21 AM
 
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Forgot to mention-

You should first center your screen with the Vertical and Horizontal position adjustments in the service menu.

Once the screen is centered then adjust the Overscan.

That should help your problem.
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post #4 of 8 Old 01-16-2003, 09:33 AM
 
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Overscan adjustment effects geometry slightly.

the more severe you reduce it the more correction you need.

Setting it to about 4% all sides should not change or effect it enough to make major problem or need major correction.

Mine was simple to do and came out great.
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post #5 of 8 Old 01-17-2003, 09:32 AM
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The overscan and geometry correction is not too difficult but is nowhere near as easy/flexible as Mits (or Panny or Toshiba for that matter). After being used to Mits (which has a seperate service menu stricly for geometry), I got frustrated at times trying to perfect our Hitachi (61SWX10b).

[rant]
I can't figure out for the life of me why Hitachi continues to use analog controls for overscan...I like to do all my geometry calibrations from the remote, not squatting in front of the TV with a screwdriver. Hopefully next year they will move to all-digital controls! Until then, I still consider Hitachi calibration unfriendly.
[/rant]
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post #6 of 8 Old 01-17-2003, 11:31 PM
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They are using overscan to compensate for tube / circuit design that doesn't really allow for the reproduction of complete 1080i line information.
Before the information is fully "painted" horizontally across, retrace forces the beam spot to drop to the next line. Manufacturers use overscan to hide potential 'fold over'.
I know that many of you have successfully reduced overscan to a point where you can see more information form patterns from AVIA or VE. The questionable long term aspect that remains is have you over-taxed the convergence ICs? Forcing the grid into a squeeze that might not be calculated at the circuit design stage and signed off at the engineering level for production might lead to premature failure.

I'm not saying you should not do it and I'm not predicting that doom will ensue, however, everything done by a manufacturer is for a reason...good or bad.

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post #7 of 8 Old 04-08-2003, 09:43 AM
 
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Quote:
Originally posted by Coyotes
They are using overscan to compensate for tube / circuit design that doesn't really allow for the reproduction of complete 1080i line information.
Before the information is fully "painted" horizontally across, retrace forces the beam spot to drop to the next line. Manufacturers use overscan to hide potential 'fold over'.
I know that many of you have successfully reduced overscan to a point where you can see more information form patterns from AVIA or VE. The questionable long term aspect that remains is have you over-taxed the convergence ICs? Forcing the grid into a squeeze that might not be calculated at the circuit design stage and signed off at the engineering level for production might lead to premature failure.

I'm not saying you should not do it and I'm not predicting that doom will ensue, however, everything done by a manufacturer is for a reason...good or bad.
I hear what you are saying.

I read Joe Kane's article in Widescreen review this month about this. David Abrams had a good post running about it too....though confusion creeps in at times to drown out the good content.

You are correct.

However,

because of the "magic focus" auto convergence system Hitachi's require overscan in order to funtion correctly. This keeps overscan reduction to a conservative level.

Most people do not reduce overscan to less than 4%, which should be the lowest you go in order to make everything work right. Some Mits owners here run 2% which is way too low....for a Hitachi
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post #8 of 8 Old 05-06-2003, 05:49 AM
 
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Quote:
Originally posted by Coyotes
They are using overscan to compensate for tube / circuit design that doesn't really allow for the reproduction of complete 1080i line information.
Before the information is fully "painted" horizontally across, retrace forces the beam spot to drop to the next line. Manufacturers use overscan to hide potential 'fold over'.
I know that many of you have successfully reduced overscan to a point where you can see more information form patterns from AVIA or VE. The questionable long term aspect that remains is have you over-taxed the convergence ICs? Forcing the grid into a squeeze that might not be calculated at the circuit design stage and signed off at the engineering level for production might lead to premature failure.

I'm not saying you should not do it and I'm not predicting that doom will ensue, however, everything done by a manufacturer is for a reason...good or bad.
So you think that running 3.5% or 4% overscan might burn out the convergence IC's quicker?


My dad's 61" SWX20B is over two years old and the CRT's are quite worn, he watched the TV atleast 5-8 hours everyday between my Mom in the morning and Him at night.

Still working great..... Hopefully it will stay that way.:)
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