Blue, Green and Red lines at top of monitor screen

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lettuce
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Blue, Green and Red lines at top of monitor screen

Post by lettuce »

So i have a Hantarex CT 28 EQ Monitor and notice that at the very top of the screen there is a Blue, Green and Red line that run across the screen....

Image

they are only noticeable on a black or dark background but are there all the time during gaming, now i can adjust the screen height so there not visible but i kind want to know whats causing them and if it can be fixed, anyone know??
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Syntax
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Re: Blue, Green and Red lines at top of monitor screen

Post by Syntax »

Happy to be corrected but they are supposed to be there just tuned off screen.
Keen on more info on the matter myself.
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lettuce
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Re: Blue, Green and Red lines at top of monitor screen

Post by lettuce »

Syntax wrote:Happy to be corrected but they are supposed to be there just tuned off screen.
Keen on more info on the matter myself.
Not sure but they are actual on the active part of the screen as said when gaming you can still seem them under the gaming display but especially noticeable on dark screens
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Syntax
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Re: Blue, Green and Red lines at top of monitor screen

Post by Syntax »

Do you have any pal systems you can test?
gray117
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Re: Blue, Green and Red lines at top of monitor screen

Post by gray117 »

I believe the rgb lines are by design, and generally to test the rgb guns are working correctly. Normally they should be off the screen. For example, they are typically visible on many 4:3 trinitrons that have aspect ratio control - the picture is squashed to widescreen on a 4:3 and these rgb lines are now visible (and no way to now hide them since the aspect ratio support is basically a geometry hack).

Why are they appearing so low down? No specific idea ... but based on sony fiddling:

i) Vertical blanking maybe off - is there an option to adjust vblank or similar somewhere? Basically if this is a fault and not something by design I think these lines are drawing in probably too late and appearing further down screen than intended ...

ii) There's a diagnostic option somewhere in a menu or a switch that might turn these off? Possible they can just be turned off/disabled.


And after a google:

iii) Similar thing was reported here
https://forum.arcadeotaku.com/viewtopic.php?t=28828

... No idea if this means it's a 'feature' of these montiors and/or the whether it's worth contacting user there to see if there was a specific fix they found. Very odd they appear only when active portion of the screen is black for this user... same for you?
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lettuce
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Re: Blue, Green and Red lines at top of monitor screen

Post by lettuce »

Syntax wrote:Do you have any pal systems you can test?
Sadly not
gray117 wrote:I believe the rgb lines are by design, and generally to test the rgb guns are working correctly. Normally they should be off the screen. For example, they are typically visible on many 4:3 trinitrons that have aspect ratio control - the picture is squashed to widescreen on a 4:3 and these rgb lines are now visible (and no way to now hide them since the aspect ratio support is basically a geometry hack).

Why are they appearing so low down? No specific idea ... but based on sony fiddling:

i) Vertical blanking maybe off - is there an option to adjust vblank or similar somewhere? Basically if this is a fault and not something by design I think these lines are drawing in probably too late and appearing further down screen than intended ...

ii) There's a diagnostic option somewhere in a menu or a switch that might turn these off? Possible they can just be turned off/disabled.

Dont think i have an option for that, here a image of the rear control panel....

Image

unless theres a pot on the chassis itself...i do have the manual somewhere but cant find it atm.

I should point out im using the VGA input as when i tried the scart socket i was never able to get an RGB image only composite
PogOrion
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Re: Blue, Green and Red lines at top of monitor screen

Post by PogOrion »

On my Sony PVM 14M4 the V Blanking setting in the service menu raises and lowers these lines.
gray117
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Re: Blue, Green and Red lines at top of monitor screen

Post by gray117 »

Dig out the manuals, they might refer to blanking with another name :) I've no idea about this specific monitor - but I'd be tempted to give those pots in the vert section a screw :shock: ... especially that vert frequency, that can't be refresh rate I don't think (?) so might be blanking? ... see what it changes ... but at your own risk - purely guesswork on my part...


Found an example of what I was talking about regards to a pvm
Problem:
http://www.neogaf.com/forum/showpost.ph ... count=6875

Solution:
http://www.neogaf.com/forum/showpost.ph ... count=6877

... Hopefully yours will be similar...
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lettuce
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Re: Blue, Green and Red lines at top of monitor screen

Post by lettuce »

Thanks for the suggestions sadly the Monitor does have a OSD Menu just manual pots.

That Freq pot is sync i believe adjusting that and the screen starts to roll
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lettuce
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Re: Blue, Green and Red lines at top of monitor screen

Post by lettuce »

Ok i have found the manual for the Hantarex, there is a schematic at the back....

Image

would any of them alter the Blue, Green and Red line that run across the top of the screen?
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lettuce
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Re: Blue, Green and Red lines at top of monitor screen

Post by lettuce »

Apparently this issue can be cause by a bad pump up capacitor on the vertical output circuit usually 100uF
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