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Old 06 January 2013, 06:18   #1
Tempest 2084
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1080 Monitor Vertical Position Adjust?

My 1080 monitor is in need of some adjusting. The picture is a bit too high and I need to center it. According to the service manual (page 10) there's a vertical position adjust (R353), however I've scoured the schematic and I can't find it! Does it actually exist or is it an error in the manual?

http://www.bombjack.org/commodore/co...3140041-02.pdf

Last edited by Tempest 2084; 06 January 2013 at 16:06.
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Old 07 January 2013, 12:48   #2
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You want to link us to the schematic, not in the service manual ( Commodore Strikes Back! )
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Old 07 January 2013, 15:01   #3
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Search for TA7644CP datasheet - seems that Pin 29 is responsible for V-Height.
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Old 08 January 2013, 02:06   #4
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But how do I manipulate that? Someone suggested messing with the focusing magnets, but I'm not sure I want to do that yet.
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Old 08 January 2013, 10:08   #5
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Don't touch the focus magnets or the repair bill will be astronomical.

If you're not sure what you're doing I suggest you give it to someone here who can help you.
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Old 08 January 2013, 12:28   #6
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Yeah that's what I was thinking. The problem is that I'm in the US (SE Michigan) so it would need to be someone local or the shipping would be astronomical. I'll ask around.
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Old 08 January 2013, 17:38   #7
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As Loedown wrote - don't touch magnets - unless this is really necessary - perhaps setting them back in order can be done without huge bill but this type adjustment (V Height and V-Center) is performed in purely electronic way - i've mentioned about TA7644 because this chip seem to be deflection and signal processor for 1080 - thus if you find this chip on PCB, search for Pin 29 and try to find potentiometer connected to this pin - this potentiometer should be responsible for vertical size - however usually problem (that you need adjust something) is related to dry capacitors - it will be good to replace all electrolytic caps after 30 years work in harsh environment (heat) inside 1080. Probably those caps are responsible for geometry change.
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Old 09 January 2013, 20:01   #8
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The convergence rings cannot be used for adjusting the picture size anyway, so just don't touch them.
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Old 09 January 2013, 20:28   #9
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Yeah I didn't think so. There must be some way to do this though, all the other settings are adjustable, why not V Position?
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Old 10 January 2013, 11:35   #10
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Quote:
Originally Posted by Tempest 2084 View Post
Yeah I didn't think so. There must be some way to do this though, all the other settings are adjustable, why not V Position?

Perhaps in named differenty? Perhaps sligly adjustin V-Hold, V Position can be changed (perhaps at a cost of V Frequency range) this deflection circuit is quite old thus it is difficult to find complete data sheet to analyze what should be changed to shift V Position but fact that you need to change V Pos can be related to poor capacitor/s.
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Old 10 January 2013, 12:20   #11
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Cost cutting? Wasn't it the same on 8833 and 1438?
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Old 11 January 2013, 03:22   #12
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I tried the V hold and all I could do was make the screen roll. So no luck there.

After looking at it again it appears that the image is too low on the screen, not too high like I first thought (it had been awhile since I looked at it). My problem is that the top of the picture is a good inch/inch and a half from the top of the screen. I was able to use the V Height to extend the picture so it touches the bottom but it is still not a the top. If I was able to center the picture then use V Height I would be able to make it touch the top and bottom.

Maybe I'm wrong on all of this. Is it normal for the monitor to have an inch or so gap around the boarder where the picture doesn't go? Seems like it would be odd, but who knows?
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Old 11 January 2013, 07:56   #13
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I tried the V hold and all I could do was make the screen roll. So no luck there.

After looking at it again it appears that the image is too low on the screen, not too high like I first thought (it had been awhile since I looked at it). My problem is that the top of the picture is a good inch/inch and a half from the top of the screen. I was able to use the V Height to extend the picture so it touches the bottom but it is still not a the top. If I was able to center the picture then use V Height I would be able to make it touch the top and bottom.

Maybe I'm wrong on all of this. Is it normal for the monitor to have an inch or so gap around the boarder where the picture doesn't go? Seems like it would be odd, but who knows?
Vertical hold is for stability in the vertical scan. Vertical centre is for the position of the picture through the vertical axis. Vertical height is for the height of the image on the screen. Convergence rings on the back of the tube

http://en.wikipedia.org/wiki/Cathode..._in_color_CRTs

I ask you this, how many monitors have you ever seen with a 1" gap at the top or bottom of the screen that was intentional? The monitor clearly has a fault and we've tried to help but without a schematic we are just pushing around in the dark. You have four options at this point.

1. Leave it the way it is
2. Take it somewhere for someone to have a look at it.
3. Track down a schematic for it and then the techs on the site will give you a series of parts to look for or check
4. Buy a scandoubler and use a different monitor.
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Old 11 January 2013, 12:51   #14
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Well for right now it's option 1 since I can't find a schematic. It's annoying, but that's life I suppose.

Thanks for trying everyone. I appreciate it.
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Old 11 January 2013, 13:44   #15
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Well for right now it's option 1 since I can't find a schematic. It's annoying, but that's life I suppose.

Thanks for trying everyone. I appreciate it.
As i've mentioned earlier - if adjustment is not provided (seems that this deflection processor have no V-Center adjustment) then probably old caps are responsible for shifting picture - and i recommend to replace all electrolytic caps related to vertical deflection.
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Old 11 January 2013, 15:14   #16
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If you've got a CRT TV then buy a SCART to Component converter and forget about this horrible thing.
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