Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: Hawk Daddy on April 29, 2007, 05:13:13 am

Title: Hacking a VGA cable to an arcade monitor.
Post by: Hawk Daddy on April 29, 2007, 05:13:13 am

I've got a 19in arcade monitor, and a radeon 9200 gphx card.  I was wondering if I could hacj up a vga cable and it'll work on that monitor?  Just connect the red, green, blue, sync, and ground?  I'm not sure if it would or not, i'm going to say not but you never know.

Hawk.

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: ahofle on April 29, 2007, 11:51:23 pm

It's possible (not sure about your particular card though) but fairly difficult.  The easier solution is to get an ARcadeVGA card:
http://www.ultimarc.com/avgafaq.html

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: Chris G on April 30, 2007, 11:31:49 am

I'm not a monitor expert, but I don't see why that wouldn't work.  If you can't figure out which wire is which within the VGA cable, Ultimarc also sells a pre-labeled VGA break-out cable for $6 that makes it very easy.

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: ahofle on April 30, 2007, 11:34:21 am

Because you can't feed a 31khz (or higher) signal into an arcade monitor.  It has to be a 15khz signal which is too low for most modern video cards.

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: MonMotha on April 30, 2007, 11:43:50 am

Actually, many many modern video cards are capable of it (I've had fine luck with nVidias 5000FX series and newer - I've heard they all support it, also most newer ATi cards), though I will admit to keeping my Matrox G100 around for TV usage.  There was a time in there from around 2000-2004 where support for modes lower than VGA was spotty, but it seems to have come back.

The issue is convincing the hardware to actually run in that mode.  Windows especially won't like to do it without prodding (e.g. powerstrip), and X (Linux/BSD) will usually require a special modeline in your X config file.  Also, until the OS loads everything will be running in VGA text mode or similar, which will cause damage if fed to to a standard res monitor.   A common solution is to use something to detect the frequency of the hsync signal and either turn off sync of halve it if it is higher than 15k (a very small microcontroller is easily capable this, and I'm sure somebody sells a pre-integrated setup).

Oh, I should point out that sometimes it isn't the hsync that's the limitation, but rather the pixel clock.  You can get around this (without sacrificing authenticity in the picture) by doubling the horizontal res and then scaling everything 2:1 horizontally.  So you can run 1280x480 interlaced, but the pixel clock will be the same as VGA.

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: ahofle on April 30, 2007, 12:53:08 pm

Thanks for the better clarification.  :cheers:

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: northerngames on May 02, 2007, 08:13:15 am

I have a new unused ultimarc VGA break out for sale in my link and I would and am using a arcadevga remeber different games run at different resolutions size's so if you want native for all and not farting with resizing for each the arcadevga is the way to go it also has specific acceleration for it's specific use over the other card's.

Title: Re: Hacking a VGA cable to an arcade monitor.
Post by: Thenasty on May 04, 2007, 05:52:24 pm

Quote from: Chris G on April 30, 2007, 11:31:49 am

I'm not a monitor expert, but I don't see why that wouldn't work.  If you can't figure out which wire is which within the VGA cable, Ultimarc also sells a pre-labeled VGA break-out cable for $6 that makes it very easy.

Also, I have this for FREE, just pay $6.00 for S/H in the US only.