SCART TV+ AVGA : Black lines at the top

[Hamselv]

Hi there,

I have recently got my SCART TV working with the ArcadeVGA card.

I get a rock stable picture, great colors and all is generally happiness, except for the top inch or so (see pictures).
I get these black lines at the top of the screen, tilting one degree or so and gernally 'breaking up' the image, The lines are static and I get them in all resolutions (as far as I can tell), both on the Windows desktop and in MAME.

I have fiddled with the pots inside the TV: Height, width and H/V centering, as well as a pot controlling the "+95V power supply voltage" and one controlling the horizontal synchronisation.

With the +95V pot I can make the black lines 'squish' together and almost disappear, but at a certain point of turning the pot, the screen starts to flicker wildly.

I feel like I have tried all available combinations with these pots, so what else might be wrong?

Who can tell me, based on the images, what might be wrong?
Never mind the moir

[StephenH]

You may need to search for a "Service mode code" for your TV model, and it is probably a vertical phase that is overlapping.  

[Hamselv]

Thanks.

However, it appears that there is no service mode for my TV (Philips 21GR2550, chassis G90AE). So all my options for adjusting it lie with the pots I mentioned in my first post, I guess(?)

I am just a bit confused as there is seemingly no way of adjusting vertical sync! I have the service manual, and it only mentions a horizontal sync potentiometer (as well as the other ones I listed). There are 3 pots on the neckpiece for RGB, where the G one is labeled "G/V", but it has absolutely no influence on the sync.

I fiddled about with it all some more, and it seems I can get rid of the lines by compressing the image height, so that it is almost half the height of the screen. Of course, this is not desirable...

Does anybody have an idea how to fix this, or is my TV broken somehow?

Could the SCART cable wiring have something to do with this? I am using composite sync etc. as I am supposed to with the AVGA, but are there other options?

*sigh*

[darklegion]

Try a signal from another device that outputs rgb and see what it looks like...a game console would do.If it still happens it is a problem with the way your tv handles rgb,which could because of damage to the TV or just poor design.TV engineers design things to work well in composite mode,and don't tend to tweak things for rgb.A common effect with scart rgb is the image being shifted right or left..this is not the same effect obvioulsy but it just shows there are issues in design that are not fixed properly in some scart TV's.If other devices don't have the effect it is something wrong with your video card or the way it is setup.

[Hamselv]

Good idea about using another RGB device. As I don't have a games console, what are my other options?

Do DVD players w. SCART output send out RGB as a rule? (even cheap ones?   ).  I guess I should be able to measure that with a multimeter... Now where did I put it?

[StephenH]

Yes, DVD and other SCART output devices send RGB.  Also, modified game consoles or game consoles with RGB will work.   Also, old computers such as Apples will work too.

[Hamselv]

Well, it seems that it is not a sync problem, as I took each of the H/V sync (that are coupled into composite sync for use with SCART) and put a 100 ohm pot in between. Turning the pot would eventually cause the image to lose sync completely, but the black 'lines' were not affected at all.

The lines are actually empty space because the top 4-6 lines seem to 'diverge'. I still have no clue what this might mean!

I tried hooking the TV up to my cheap---I'm attempting to get by the auto-censor and should be beaten after I re-read the rules-- DVD player, and the image showed quite nicely, with no weird lines or anything. What is the resolution going out from a DVD player?

I guess it is just a hardware problem with my TV... I will find a more dedicated TV repair forum for help with this.

Anyway, I played around with Minwah's excellent Resolution Tool, and it seems that my TV can display all the ArcadeVGA resolutions with 288 lines (352x288, 384x288, 512x288 and 640x288) pretty well! Half the top line is missing and perhaps the bottom line as well, but nothing too obtrusive.

But somehow these resolutions seem to strain the eyes more than the others..?. When I pick a game and set the resolution first to something really close to the original resolution and then afterwards to the closest x288 resolution, I swear that the x288 has more of that 'too low refresh rate' feel from that can be seen with PC monitors. Not quite as bad as a PC monitor set at 60Hz, but close.  Can any of you gurus explain this?

I can't really tell the difference between the picture quality between each resolution, just a slight flickering sensation from the x288's.

Anyway, I guess once I put some glass in front of the screen and get some more viewing distance, things might be quite OK.... But I am afraid I can more or less forget about running Daphne and Vpinball with only x288 resolutions, or...?

Thanks...

[rchadd]

maybe hardware problem with the AVGA card? suggest you contact andy about it.

My AVGA connected to a Panasonic Portable using SCART and i got perfect display without needing any adjustments.

[AmericanDemon]

It could be handling the overscan from the PC input strangely.  Grab Powerstrip and try to do some custom resolutions.