25Khz modeline for Xserver

[AMIGrAve]

Hi all,

I was hoping that some linux guys here could help me about a 25Khz xfree server modeline. I made a vga -> arcade cable for my virtua fighter cab monitor, but I guess that the voltage does not match. It's too dark to see something while I'm testing the modeline. So I'm testing this with my NEC MultiSync monitor which seems to support 25Khz. After playing with the modeline calculator, I manage to get a stable picture but it is not perfect because there's still a mess with the horizontal lines. As I'm not used to deal with modeline problem, I don't know what I should do in order to get a good picture, but perhaps that some of you will immediately recognize the problem while looking at the photos hereby.

I made my tests using knoppix.
Here's my modeline :

Modeline "512x384" 15.38 512 544 600 632 384 392 396 404 -HSync +VSync

I don't know what to change in my modeline in order to display properly

Here's some pics displaying the kde desktop, and you can see the display problem.

http://www.amigrave.com/25khz/25Khz_on_Nec_01.jpg
http://www.amigrave.com/25khz/25Khz_on_Nec_02.jpg
http://www.amigrave.com/25khz/25Khz_on_Nec_03.jpg
http://www.amigrave.com/25khz/25Khz_on_Nec_04.jpg

[Dak-ak]

two things come to mind...

1) see if your on-screen display tells you what your refresh is, i would be curious to say what it says...

2) i would try bumping up the pclock, see if it will show up correctly for you then...

Modeline "512x384" 19.72 512 544 616 648 384 391 396 404 -HSync +VSync

something you may want to try, if your NEC goes up to 50Khz, is to use doublescan.  You double the pclock and use doublescan, you can test, and then drop the pclock and doublescan option when you go back to using the arcade monitor.

Modeline "512x384" 30.76 512 544 600 632 384 392 396 404 -HSync +VSync doublescan

my best guesses.

[AMIGrAve]

1) see if your on-screen display tells you what your refresh is, i would be curious to say what it says...

I don't have one, I have an old monitor (I guess you talk about the little lcd displaying infos about resolutions, etc)

2) i would try bumping up the pclock, see if it will show up correctly for you then...
Modeline "512x384" 19.72 512 544 616 648 384 391 396 404 -HSync +VSync

I get this error from nv module while starting X:
(EE) NV(0):Virtual height (0) is too small for the hardware (min 128)

something you may want to try, if your NEC goes up to 50Khz, is to use doublescan.  You double the pclock and use doublescan, you can test, and then drop the pclock and doublescan option when you go back to using the arcade monitor.

Modeline "512x384" 30.76 512 544 600 632 384 392 396 404 -HSync +VSync doublescan

Yeah! This one works. I guess that my NEC does not support 25Khz and this is why I get the screen with line offsets. Thanks dude !

But I guess my vga -> arcade cable is wrong. Do you know what to do when the monitor has only one wire for synchronisation ? I put the Hsync and VSync from the vga cable together but it does not seems to work.

[tom61]

It's too dark to see something while I'm testing the modeline.

You could get a video amp from Ultimarc.com .

[AMIGrAve]

Yeps ! That's what I'll do. I think the problem with my NEC is due to the fact that it does not support 25Khz
Because Dak-ak pointed to me that I could try doublescan and it work so I guess that my modeline is good but the monitor does not handle 25Khz.

I made a vga->arcade cable that doesn't work because I put the VGA HSync and VSync together for the arcade Sync, but as someone said to me; it's not that simple you idiot !

I saw that the J-Pac could generate the CSync from a VGA VSync and HSync, I guess that's what I need, and the J-Pac will amplify the voltage so that's good for me.

I don't know if there's any software involved with the J-Pac but in this case I hope that there's no problem running J-Pac with linux.

[Dak-ak]

Modeline "512x384" 19.72 512 544 616 648 384 391 396 404 -HSync +VSync

i had to use negative hsyncs and vsyncs in order to get a picture to show up on my arcade monitor... YMMV

[AMIGrAve]

i had to use negative hsyncs and vsyncs in order to get a picture to show up on my arcade monitor... YMMV

Do you mean that you just wired the HSync and Vsync of your vga card together, used -HSync and -Vsync for your modeline and it worked ?
Someone told me that I couldn't reproduce the Composite Sync arcade monitor signal just by wiring HSync and VSync together !?
Your arcade monitor is ok to receive 1 volt instead of 5 ? (or did you had a plot to adjust ?)

[Dak-ak]

Im not sure what I did with the wiring *thinks*..

I just followed ultimarc's guide to wiring 'er up.  My monitor was jamma compatible so there is a good chance it had composite sync... If i didn't specify -vsync and -hsync, i would get a black screen...

as far as brightness, my monitor looks fine... I had to turn the brightness all the way up all/nearly all the way, and just dialed the contrast down until the black became black...

[tom61]

I don't know if there's any software involved with the J-Pac but in this case I hope that there's no problem running J-Pac with linux.

It needs no drivers, it just needs to be connected to the keyboard port for power. Is your cabinet Jamma? If so, hooking up the J-Pac will take care of your keyboard encoding needs as well. You'll have to switch it to 25kHz mode using the jumpers, otherwise it'll prevent anything higher than 15kHz from getting to the monitor.

[AMIGrAve]

It needs no drivers, it just needs to be connected to the keyboard port for power.

Perhaps I misunderstood the use of the J-Pac (my english is not very good at reading and writing ... hum I don't speak very well either !  anyway, I read the information page about the J-Pac, and I tought it would allow to wire the cab controls directly to this card. Am I wrong ? If not, I guess we should be able to configure wich control is mapped to which key, and then there is some software configuration involved. But, hearing me speaking, I think I didn't understood anything at all

Is your cabinet Jamma?

No it is not.

You'll have to switch it to 25kHz mode using the jumpers, otherwise it'll prevent anything higher than 15kHz from getting to the monitor.

 
If a 25Khz monitor receives a 15Khz signal, will the monitor be damaged ?

And if a 15Khz monitor receives a 25Khz signal, is it the same ?