Geometry adjustment knobs inside the housing?

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Old 07-13-13, 11:58 PM
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Geometry adjustment knobs inside the housing?

Hey all,

I have a Panasonic CT30WX52 television. It's an HD tube, not a common type, got it very gently used a couple of years ago.

I've noticed that modern HD broadcast signals make more use of the picture than older SD signals did, in that modern LCD HD TVs run the image right up to the edge. Older TVs had some portion of the image concealed behind the plastic frame around the CRT.

This CRT TV operates in the old style, with portions of the image as designed in the new style off the edge, and occasionally some things, like weather information and some closed captioning are not visible on-screen, cut off at the edge.

Since the TV weighs 126lb, if anyone can confirm if there are manual horizontal and vertical sync/hold knobs before I drag it out of its cubby and open it, I'd much appreciate it.

I've opened CRT computer monitors to adjust the picture position and size before, but it has been awhile. I tried looking up technical service information on the unit but couldn't find anything beyond users' manuals which don't go into such details.

Thanks,
 
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Old 07-14-13, 09:47 AM
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You can sometimes adjust the screen layout using the menu on the cable/satellite receiver box. It should bring up an on-screen menu where you can choose between 480, 480 stretched, 480 zoom etc. The trade off is that you will end up with black bars across the top and bottom of the screen in 16:9 format. But it will bring in the side elements for you to see.
 
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Old 07-14-13, 09:59 AM
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Yeah, the adjustments between the HDTV tuner and TV don't really work. If I set the preset to where I can see the whole image I end up with a couple inches of unused screen real-estate around the edges. I need the fine tuning adjustments to really improve it.
 
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Old 07-14-13, 11:26 AM
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I'm guessing you tried changing the ASPECT ratio from your remote control.
full..... 4:3 ..... zoom ...... just.

The other adjustments you want to make will probably not be right there waiting to be adjusted. I have a partial service manual and it shows only a width adjustment but it's not a pot. you turn.
 
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Old 07-14-13, 05:12 PM
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Yeah, I want to reduce the vertical size and I expect that I'd need to tweak the vertical hold a bit at the same time. I do need to adjust the horizontal size too.

I guess the term for what I'm attempting to fix is the overscan. I lose too much picture in overscan now that modern broadcasts don't leave as much margin for overscan as older broadcasts on CRT televisions called for.
 
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Old 07-15-13, 04:31 AM
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You may have to resort to adjusting the magnet rings on the neck of the CRT. Mark their positions or snap a photo before you start so you can reset them.
 
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Old 07-15-13, 07:59 AM
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Ick! If I open the housing and find that I have to go to that level then I think I'll just leave it alone...
 
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Old 07-15-13, 06:26 PM
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Some TV sets have a "service menu" accessed by pushing some buttons on the remote in a sequence not described in the instruction manual. If this is present then it usually includes adjustments for height and width.

On some sets the overall picture size will vary a little over the course of a program, usually with the picture being a little larger when the overall content is quite light. This size changing will be quite obtrusive if you adjusted the height and width to represent almost no overscan.
 
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Old 07-15-13, 08:06 PM
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Yeah.....adjusting the magnetic rings is a lesson in futility. If you don't have the right test patterns you'll end up with a mess.
 
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Old 07-15-13, 08:08 PM
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I may see if there's a tech hidden menu, I don't need to completely eliminate overscan, but right now on some stations, the network's "bug" is half-cut-off at the bottom.

If I can't do anything about it then I'll just live with it. Will have to see.
 
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Old 07-16-13, 04:06 AM
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I've done it several times to adjust convergence on those old sets, and I'm not a pro repair tech. All it takes is a bit of patience.

And remember: One had in the pocket at all times.
 
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Old 07-16-13, 08:07 AM
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Well, it appears that Panasonic has a hidden tech menu, but it's mildly obtuse in its use, at least on the different model that I found that indicated how to reach it. It displays code numbers that correspond to various settings, and then one uses the volume controls to adjust the setting.

I'll have to go through this documentation that I found for that other model TV and write down the codes that I think are relevant to the adjustments that I want to make, and go from there.
 
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