VGA to RGBHV

[zebra100]

I have a RGB screen navigation on Mercedes which I want to convert to accept VGA signal. I found the screen is a
Sharp 5" with RGB analogue and HV lines.  I connected to VGA RGB and HV lines and blocked the original RGBHV lines from Navigation. Sure, the screen is blank, but no signal from the VGA port from notebook and it said no external display from PC.  I didn't connect all the ground lines from the VGA port of notebook, is this cause the blank screen or you can skip the ground lines.  On VGA you have ground lines for every single line, is that I can gorund them all together?

[kendrick]

Without more information about the screen you're using, we can't be much help. What sync rates will it accept? If it will actually accept RGB, then it's doing so at 15 Khz at a maximum and it won't accept the 30 KHz (or more) from your VGA source. If you're very lucky, it does take 30 Khz exactly (producing a 640x480 screen at that rate) so try that resolution. It's very unlikely that your scavenged part will accept multiple scan rates.

[Tiido Priimägi]

The Netbook is most likely trying to communicate with the monitor (there's 2 digital data lines for that) and seeing no response, it won't output anything... you might try to make the compy output signal over the VGA by using some other monitor, then unhook it and have the LCD connected to it.... you might have to buffer the sync signals also, and its never a bad idea to connect all grounds on the VGA connector on the compy side, you'll never know how is "something is connected" done, I know I use some GND signals on the VGA port of my Dreamcast so it autoswitches to VGA when something is connected

[zebra100]

Thanks to the quick response.  the thing is the screen is still on mercedes navigation, what I intend to do is hijack the screen to put a VGA input, this is very easy done on a toyota Lexus which seperate the nav and the screen, Mercedes is a bundle, but I have found the Sharp screen  white paper here http://document.sharpsma.com/files/LQ5AW136_SP_122605.pdf

I dismental the Navigation unit, just block the RGB and VH 5 lines ( I need the other like backligh etc stay connected to supply lights), connect it to VGA RGB and HV lines with a switch to see if it works, it block the rgb and hv alright, because all I see is white screen, but when I hooked up the VGA of notebook, it still blank, either it needs ground to be connected to both ends ( I didn't connect any ground lines at all, is it necessary?  ) or the PC need a 75 ohm detection to open the line ( I read somewhere to put a 75 ohm resistor somewhere on the VGA pin, because I only used straight lines) or I read the VGA pinout wrong, because I see two version, rgb from right 1,2,3 or from left,  as for the frequency, chould you guys help to check the doc above ( at page 11 it said horizontal fre 15.73 K ), at least I believe it should show some strip lines if fre is not right, can't be blank,

[zebra100]

Without more information about the screen you're using, we can't be much help. What sync rates will it accept? If it will actually accept RGB, then it's doing so at 15 Khz at a maximum and it won't accept the 30 KHz (or more) from your VGA source. If you're very lucky, it does take 30 Khz exactly (producing a 640x480 screen at that rate) so try that resolution. It's very unlikely that your scavenged part will accept multiple scan rates.

If the screen (see white paper in previous post) only accept 15.75K and i hooked to 30K vga from notebook, is it will be total blank or at least I will see some moving strips over the sreen?

[l_oliveira]

Some PC video cards require the 75ohm load on the RGB pins to detect that a monitor is present.
I2C (DDC) connection is a good thing to have but is not really important as the video cards are set up so they will output video even without DDC information. But no resolution limit will be imposed on the resolution options at the system settings.

Also some laptop PCs require a combination of keys be pressed to switch from the internal LCD to the external VGA port. Did you try that ? The LCD will turn off once you switch the output. As far I know it's not possible to use both on most models.

[zebra100]

Sorry for late reply. yes, acctually I tried the notebook on my hdtv before hook up to the nav.  I believe you are right, it should be the 75 ohm suto detect function of the notebook, I remember I saw somewhere that you put a 75 ohm resistor between certain pins of the VGA plug to fake the request, any idea about that?

[zebra100]

I got a notebook which has nvdia control to customize the resolution and refresh rate, which parameter should I enter for this sharp monotor as spec above?