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Common ways to hook up your laptop to TV
1. S-Video - This is probably the most common method out there currently because an S-Video cable is cheap as heck and just about every TV under the sun has a S-Video port. You'll have to make sure you laptop is equipped with this port. Remember, there are two types of S-Video cables: 4-pin and 7-pin. Most laptops and PC's are equipped with a 7-pin port, so if your TV only has a 4-pin S-Video port, then this method will not work.
2. VGA - If you have a HDTV, then you will be better off connecting using a VGA cable. It gives much better quality than S-Video and as with S-Video, the cable is very cheap. You usually won't find a VGA port on regular TV's though, so this option is if you have an HDTV.
3. DVI - DVI stands for Digital Visual Interface with "digital" being the key word there. The digital signal will give a higher quality picture than either S-Video or VGA. Of course, your computer will need to have a DVI connection and your TV will need to be an HDTV. This cord is definitely not cheap, it ranges anywhere from $40 to $80.
4. HDMI - Using HDMI will give you the best quality by far. Only a few computers that I know of have HDMI ports, but you can get a DVI to HDMI cable to connect it to your HDTV. HDMI is compatible with DVI.
5. Scan Converter Box - This is the last method that I could think of and it involves using a scan converter box, which takes a VGA signal and converts it into S-Video or component video.
Check your VGA cable. Some cables have only 14 pins, some have all 15. The missing pin is pin 9, in the 15 pin cable. It carries 5V from the graphics card to the screen.
Without that 5V signal most LCD and Plasma television screens won't recognise a PC input. The cable that came with your PC most likely only has 14 ins as that is all a monitor screen needs.
This is the probable solution and you can purchase a 15 pin cable at most PC or electronic shops, just check that is does have all 15 pins befiore you buy it. The cheap ones are just as good as the expensive ones unless you are buying 20 foot cable. For 6 foot cable the cheap ones are just as good as the expensive ones.
You seem to indicate the Cable is not the problem because you have hooked up other laptops to the TV.
have you set up th elaptop to supply a signal to the VGA?
According to Ask-Leo, most laptops built today include an external monitor connection. Most are VGA, but some are starting to include DVI digital video connections instead.
The 'trick', if you want to call it that, is that they are not enabled by default. You need to take action to send video out that port. Typically, and this varies from laptop to laptop, there is a keystroke that does exactly that.
Unfortunately, it's not a simple as turning it on or off.
First, realize that in order to enable the CRT/LCD keystroke you typically need to be holding down an additional key; on my Dell it's a blue "FN" key. It operates very much like CTRL or SHIFT, in that you hold it down to enable the blue functions that are printed on the key tops. So in my case it's Fn + CRT/LCD to enable the external monitor.
Second, realize that it's not on/off. Pressing the key repeatedly cycles though a series of combinations. For example, each time you press that key, you may cycle through these combinations:
LCD (laptop screen) only, the CRT (external screen) is off.
CRT only, the LCD is off.
LCD and CRT both on, and displaying the same thing on both screens.
LCD and CRT both on, but displaying different things - together they form a larger virtual desktop where the LCD might be displaying the right side, and the CRT the left.
When you hit the keystroke, the configuration changes to the next one in the list; when you reach the last, it starts over at the beginning.
Your list of configurations or combinations may be different, or in a different order. There is no standard, and each laptop may be different.
Third, and this is perhaps most important because it's the source of much frustration, it can take up to 5 or even 10 seconds for each new setting to take. And 5-10 seconds is a long time when you're standing in front of people trying to ready your presentation.
After typing the keystroke to change your LCD/CRT configuration, give the new combination at least 5 seconds to take before you decide it didn't work. Be patient. There are several hardware related reasons for this; most typically the time it takes your CRT or projector to 'sync up' to the signal that it's suddenly receiving.
The last combination where both your laptop screen and your CRT are on and displaying two different portions of a single virtual desktop warrants a little more clarification.
The likelihood of the LCD and the CRT being the same resolution or "size" in pixels is very low. You can see this when you look at the display settings in Windows:
You can see that while my laptop's LCD is 1440x900, the CRT/VGA output is set to 800x600. While you can often change the resolution of the VGA output, it's unlikely that you'll be able to match the native resolution of your LCD. The result is what you see - a virtual desktop that's not a perfect rectangle. That's something you simply need to be aware of as you move applications between the two for your display.