Scanlines thicker at the top and bottom of CRT image

andykara2003 · Post by **andykara2003** » Fri Dec 12, 2014 8:01 pm

I have been lucky to find a late 90's 50Hz Sony CRT TV (KV-X2500B) that has only ever been used for a few hours. The image is mint, absolutely no convergence or geometry issues, pin sharp etc.

The only thing I'm noticing is that the scanlines are thicker near the top and bottom of the image than in the centre. Would anyone be able to shed any light on why this is?

Cheers

Xyga · Post by **Xyga** » Fri Dec 12, 2014 8:27 pm

Probably requires vertical linearity (v_linearity) adjustment.

Look for the service manual of your TV model and see in it if you can do it from the menu.

andykara2003 · Post by **andykara2003** » Fri Dec 12, 2014 8:39 pm

Cheers - I wondered if it might be that - I'll have a look in the service menu. What would be the best test pattern to use to get the vertical linearity right?

Xyga · Post by **Xyga** » Fri Dec 12, 2014 8:45 pm

Circles 'pattern' I think, display circles and make sure they're really round, not oval.

The 240p test suite has got one: http://junkerhq.net/xrgb/index.php/240p_test_suite

EDIT: this pic combines a grid and circles, if you're going to use a pc in 15KHz or whatever: http://screenshots.ubuntu.com/screensho ... _large.png

andykara2003 · Post by **andykara2003** » Fri Dec 12, 2014 8:59 pm

Very much appreciated, thanks for that. I'll get on it in the morning

Xyga · Post by **Xyga** » Fri Dec 12, 2014 10:23 pm

Oh don't thank me yet ! I don't know that Sony chassis model so this is just speculation, and the only two times I remember trying to adjust linearity on crts I did it completely at random just looking a the Green Hill Zone checkered walls in Sonic.

By the way: always take note of the service menu's settings default values before changing anything.

blizzz · Post by **blizzz** » Fri Dec 12, 2014 10:36 pm

Just checked the service manual, pages 23 & 26. The setting to fix this should be "S.Corr". Vertical S-Correction expands/compresses the top and bottom of the screen compared to the middle.

andykara2003 · Post by **andykara2003** » Fri Dec 12, 2014 11:07 pm

Thanks Blizzz! That's great to know - I've been messing around with vertical linearity baffled at why it wasn't working. Can I ask where you got the manual?

_rm_ · Post by **_rm_** » Sat Dec 13, 2014 12:03 am

Although the Circles pattern is the usual "tool" to resolve your problem, sometimes i also use a simple ruler to mesure the exact size of the squares along the entire screeen

andykara2003 · Post by **andykara2003** » Sat Dec 13, 2014 12:06 am

Seems like that would be just as effective...

Xyga · Post by **Xyga** » Sat Dec 13, 2014 12:11 am

Yeah a ruler is good ! Or a compass. Classroom tools ftw !

_rm_ · Post by **_rm_** » Sat Dec 13, 2014 12:36 am

Xyga wrote:Yeah a ruler is good ! Or a compass. Classroom tools ftw !

You are precisely right,lol, because a set-square is also excelent to set perfect geometry.

blizzz · Post by **blizzz** » Sat Dec 13, 2014 10:55 am

andykara2003 wrote:Can I ask where you got the manual?

I just googled for "KV-X2500B service menu".

andykara2003 · Post by **andykara2003** » Sat Dec 13, 2014 11:11 am

Got it - thanks for the help, the problem is sorted now

shmups.system11.org

Scanlines thicker at the top and bottom of CRT image

Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image

Re: Scanlines thicker at the top and bottom of CRT image