Query about connecting VGA outputs to DVI inputs

[aceizace]

Hi there. Warning, long story. I used to have a 15" HDTV, it was an Acoustic Solutions ASTV-1615HDS, here's the spec:
http://www.argos.co.uk/static/Product/partNumber/5291986.htm

I bought my one off ebay. I sent it back to the seller about a week ago, because I thought the DVI port didn't work. I tried plugging my xbox into it with the component cable, which worked fine except the TV wasn't widescreen, and the xbox would only output in that. I read that if you use the VGA cable it would letterbox it, so I did and it did. Fine. But then I wanted to plug my laptop in as well, which has a VGA output. So I thought I'd would use the DVI port of my TV, since the xbox was using the VGA. So I got a VGA - DVI cable off ebay, it didn't work, but I figured it was because it was only DVI-a cable, and I managed to get my money back since it was advertised as DVI-I. So then I made sure I got a VGA - DVI-I cable, but that didn't work either. I'd read on this website: http://features.teamxbox.com/xbox/1245/Xbox-360-FAQs/p2/ (question 19) that you can use an adaptor to plug the xbox into a DVI port, so I thought I'd get one, this one: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110130475494. But that didn't work either!

So I decided the TV must be broken, so I contacted the seller, and then sent it back, and he gave me a refund. So I bought a new TV, an upgrade in fact. This one: http://www.argos.co.uk/static/Product/partNumber/5292040.htm. I stuck with acoustic solutions since I loved everything about the previous TV apart from the DVI port.

Now my problem, I tried my second cable to plug my laptop into the new TV, and it doesn't work. My xbox is actually away for repairs at the moment, so I haven't tested using that with the adaptor. But I'm starting to wonder whether it's really possible to plug either of my devices into the DVI port... I mean, I've found things like this: http://cgi.ebay.co.uk/GEFEN-VGA-TO-DVI-CONVERTER-TRANSCODER-EXT-VGA-2-DVI_W0QQitemZ579...QQcmdZViewItem which "convert" from the VGA signal to DVI. So, can someone shed some light on this? I think I'm probably not understanding how DVI and VGA actually work. And I'm starting to think that maybe my TV only accepts digital DVI signals? I don't know.

Having said all that, at least I can use the component xbox cable now (since the TV's widescreen), and then get a VGA cable for my laptop. Bit of a waste of money on all those cables, but oh well.

Thanks for your help!
-
Andrew

(NOTE: When I say "xbox" I mean "xbox 360" =D)

[yoda313]

The vga-dvi should be all you need. Though I can't imagine them being that expensive. One was included in my nvidia card. I had a dvi only output and it had a dvi-vga converter. I currently only have an old 17" vga crt monitor. The dvi-vga converter worked perfectly. I have since upgraded to a newer nvidia card. It has both vga and dvi outputs so I just simply plug it into the vga port now.

But basically the converters should do the trick. Mine is a simple dongle deal that is really small and not a box. I'd say keep looking and you'll probably find a better deal.

[aceizace]

The vga-dvi should be all you need. Though I can't imagine them being that expensive. One was included in my nvidia card. I had a dvi only output and it had a dvi-vga converter. I currently only have an old 17" vga crt monitor. The dvi-vga converter worked perfectly. I have since upgraded to a newer nvidia card. It has both vga and dvi outputs so I just simply plug it into the vga port now.

But basically the converters should do the trick. Mine is a simple dongle deal that is really small and not a box. I'd say keep looking and you'll probably find a better deal.

When you say converter do you mean an adaptor, like the third link in my post?

I am not trying to convert a DVI signal into a VGA one, I am trying to go the other way. My laptop only has VGA out, and it isn't displaying when I use a VGA-DVI cable, which is the same as using an adaptor I suppose. The converters I'm talking about seem to range from £70 - £250, they actually change the signal I think, and that is what I would need.

In my case, it's the monitor that has the DVI port, and basically what I'm trying to find out is whether it just doesn't display an analogue signal sent along a DVI cable (like a DVI-a cable) or whether the cable just isn't sending it properly.

[redwudz]

VGA= Analog video
DVI= Digital video

Those two are not interchangeable.

I think where some confusion comes in is that some DVI connections also have analog signals on them. The cable you use picks which signal you get. But not all devices have both formats in a single socket. S-video did a similar setup, with both s-video and composite on the same socket. It's done to save space,

This might explain it a little better: http://www.interfacebus.com/Design_Connector_Digital_Visual_Interface_DVI_Bus.html

There are digital<>analog converter boxes, but unless you have both formats available, just a cable won't convert anything.

[edDV]

Monitors usually split the connectors into VGA (analog) and DVI-D (digital). You can't get from VGA to DVI-D.
http://en.wikipedia.org/wiki/Video_Graphics_Array
http://en.wikipedia.org/wiki/DVI

Most display cards have either DVI-A (DVI-D+VGA pins) or just VGA.