picture problem with resolution 240 lines

[stiegi]

Hello!

I have got a problem with games running at 240 lines such as Cadash 320x240 or Rastan 320x240. I am using groovy mame 0.149. The other resolutions with 224 lines for example Shinobi 320x224 donīt give me any problem. The problem I have got is that the picture with 240 lines is not displayed properly at the top i.e. 2-3 lines "spread" apart from the game picture itself - they are not aligned with the picture. I thought it was a TV issue but it is not and games with 224 lines show a normal picture without any lines apart.

I zoomed the picture with the resolution 320x240 out with the potis on my crt tv so that you can see black borders at the top and the bottom and still could see the problem that 2-3 lines are not lined up with the picture - therefore I think that groovy mame does not display pictures with the resolution of 240 lines correctly. It is not a tv issue.

I canīt figure out what is wrong with the configuration - has it got something to do with the settings in arcade osd? I would really appreciate if someone could help me.

regards,

[Paradroid]

It is not a tv issue.

Sure about that? GroovyMAME handles 240 lines just fine on my TVs...

Try adjusting the vertical centering of the picture using Arcade OSD and see if different porch values make your TV happier. Sometimes pushing the whole frame further down eliminates distortion in the top few lines. I have certainly experienced this with B&O sets that put a slight curve in the top few scanlines when using the default settings.

Out of interest, what brand and model of TV are you using?

[stiegi]

Hello Paradroid!

The specific model I use is a Philips 21gr2350 which is a quite old model. It has a good picture and there is also the possibility to adjust different geometry settings which was the reason why I put it into the mame cab. I played around in the arcade osd but it did not help some lines at the top still spread away from the picture. By the way I did notice something interesting - with games such as pang which also use 240 lines the picture is ok and the reason is that it has got 57hz refresh rate but all the other games with 240 lines and 60hz do have a problem with the picture. It looks like some parameter in groovymame gets off when 240lines and 60hz is required.

I have mounted the tv into the cab again but I use it as vertical monitor again because most of the games have got 224p and are displayed properly. Nevertheless I get the same problem with vertical games which have 240p such as slap fight, joust2, centipede etc.
- you can see in the nag screen which shows the screen resolution already that the picture is distorted and even the lines of the nag screen get crossed. Other than that games with 240p and say 57hz seem to be ok.

I have got another model (the same) and I am going to test this one whether it shows the same issue.

Regards,

[haynor666]

I think Your TV might be PAL only. That's why it work with 57 Hz but does not work with 60 Hz.

[stiegi]

Hello!

This is definitely not the case - the tv can even sync to 61hz properly for example nibbler works great in groovymame or games such as galaga with vertical refresh rate of 60,6

I tested the second Philips tv which is the same model and it had also the problem with 240p. Therefore I donīt think that the tv has a technical problem perhaps it has a problem with the setup.

For example burger time with 240p and 57hz can be adjusted with vertical potis without any problem - I think there might be a problem with the monitor settings. Whenever a game is displayed at 240p it is drawn with the "incorrect lines" right from the start - the adjustment potis on the tv DO NOT distort the game - they just make the "wrong" lines more or less invisible.

Is it possible that the graphics card can be the issue?

regards,

[stiegi]

Hello guys!

I just looked up the service manual for the Philips TV and it says that it is pal - so it is a 50Hz tv. If this is true I donīt understand how it can sync to games with 60Hz and 224lines properly in groovymame. Is there a connection between the number of lines displayed and refresh rate? For example with a lower number of lines the tv can achieve a higher refresh rate? It looks like this is the case and for games with 240 lines the tv can also sync in groovymame but gets some picture issues because 60Hz are too high. As stated before when a game such as Pang (240 lines; 57Hz) the Pal TV the picture is correct in groovymame.

By the way can anyone recommend me a TV (in Europe!!!!!!!!!!) which can display games with 240p and 60Hz properly in groovymame. The problem is that there are only very few TVs which are capable of doing so 50/60Hz shown at the backside of the TV. Otherwise the only possibility would be to get a TV from America which uses NTSC (60Hz).

regards,

[Calamity]

Is there a connection between the number of lines displayed and refresh rate?

Sure:

Vfreq (Hz) = Hfreq (kHz) / total lines

[adder]

hello stiegi post your groovymame  mame.ini file here

[stiegi]

Hello guys!

Sometimes it takes some time to solve a problem although I did not really believe in it. I was nearly about to test another TV

since I thought it is a mere technical issue. Today I adjusted the vertical back porch, the vertical front porch and the vertical

sync pulse and also took care of the vertical switch and picture height poti on the main chassis of the TV. Thanks to arcade OSD

it is very comfortable to try out different values in order to achieve this goal. The trick is to transfer the correct values into groovy

mame ini file (monitor presets) and set monitor to custom - now groovymame will take exactly this values and will not recalculate

them.

Regards,

Lex