Question : Problem: DVI knowledge needed

Hi guys,

I have a question regarding DVI ports and LCD Displays. I have a brand new Apple powerbook with a DVI output. The user's guide does not specify what kind of DVI port it is. I know there are two kinds of it (DVI-I and D?).
With the laptop there is also a DVI-to-VGA adapter. I used this adapter to connect a VGA display and it works perfectly. So the port in the laptop is working ok.
I have bought a Sharp Aquos LCD TV (32 inches) with a DVI-I input. When I connect the powerbook nothing happens. The TV does not detect the laptop and the laptop does not detect the TV. Bought screens blink during a couple of seconds, but after that, everything is normal again. It seems that they can see each other, but for some reason, after the blink, it is like they are not connected at all.
I have tried a second cable and the problem is the same. I have also tried to change the resolutions with no success.
I am new in DVI and all those things. Could it be an incompatibility between the DVI in my powerbook and the DVI-I of my TV? Is there a special kind of cable like "DVI-to-DVI-I" or something like that?

Thanks in advance for your answers,

Guillermo Acilu

Answer : Problem: DVI knowledge needed

The port on the laptop is a "DVI-I" port, which means that it has both analog and digital outputs in the same connector.  This is the most comprehensive type of port, and virtually all ports on computers and video cards are of this type.

There are basically two likely reasons why the Sony display isn't working:

1.  The refresh settings and resolution settings of the laptop are incompatible with the Sony.  You might be able to get around this by changing these parameters on the laptop.  But I know that some Sony displays say in their manual that the DVI port is "not for computer use".  What they really mean is that the display is not compatible with common computer resolution and refresh settings.  A call to Sony might be in order here.  Another possibility (unlikely, I think, but possible), is that the Sony will not display a signal unless the signal source (laptop) implements "HDCP" (copy protection), which the laptop almost certainly does not.

OR

2.  The computer might not be configured to send a signal to the external DVI port.  Since this is an Apple product and OS, I am not able to get specific, but obviously the internal LCD screen is still present and is still being sent an image.  You might need to do "something" on the computer (setting somewhere, or even some keyboard combination) to "tell" the computer to send a signal to the DVI port (either in addition to or instead of the internal LCD display).  Another thing I'm not sure of, the DVI connector has two ports on it, an analog port and a digital port.  These could be either the same "logical" displays with two different physical connections (e.g. they would always show the same image, no matter what), or in some video systems they are two logically different displays (you can see different things on the two displays, one of which will probably correspond to the internal LCD display).  All combinations are possible and are actually implemented in different products, so there is no way to know other than to ask tech support (apple, in this case).

Finally, some hardware is configured such that it will only work if the external monitor is connected at the time that the compuer is turned on; in these cases, you can't connect something later, once the computer is running.  That doesn't sound like the situation here (and it's more common with TV video outputs than with vga or dvi), but it is a possibility.