Problem trying to use DVI connector

[nplima]

Hi all,

I've read a bit on other users' probelms with LCD screens, and apparently the issue I found here is unusual...

My Powermac AGP has a ATI 128 pro card with VGA and DVI connectors;
My HP L2335 screen has DVI and VGA connectors too. looks like a good match so far

Now, when I boot up the mac with the DVI cable (that's DVI-D , according to Wikipedia: http://en.wikipedia.org/wiki/DVI), the first screen with the Apple logo comes up at 1600x1200 resolution. when the OS boots up and is about to show the login window the screen turns blank, the screen shows "No input signal" and goes to sleep. not good.

I tried setting up the display so that the maximum resolution would be lower, and the only difference is that the apple logo shows up at 640x480, then the screen turns off. The "detect displays" shortcut doesn't detect anything, so I'm kind of stuck.

I've been using the screen with the analog VGA connector and it works, this is just a matter of optimizing things. the "native" resolution ofr this LCD is 1920x1200@75hz and that's not so good with the VGA cable. So I'm back using 1024x768 on this 23" screen, so now I can be proud of having the biggest icons in my 'hood

Thanks in advance for any help.


Nuno

 

[Makosuke]

Well, I didn't realize it, but that card does support that resolution. Wow--on 16MB no less.

Anyway, do you have a second monitor around? If so, you could hook it to the VGA output and the 23" to the DVI, then when it boots bring up the displays panel on the working monitor and use the "gather windows" command to get the settings window for the DVI output over onto the functional monitor. From there, you can goof with it and see if you can find a resolution seting that works. If it's not even seeing it at that point, I don't know what to say.

One random additional note that I'll add, even though it probably is of no use to you: On the Yikes G4s, which I think used the same graphics card in a PCI version, I've had a weird problem where some resolutions just refuse to work properly after a restart. I can set it in the control panel, and it works fine. But when I restart, blank. No signal. I needed to reset the PRAM to get an image back, then select a lower resolution.

Weird, and again, I have a feeling this is just the PCI G4s, but who knows, maybe it has something to do with the card and you're bumping into it.

 

[nplima]

sigh

Hi again,

Thanks for your help. I tried to set up the display with another CRT screen I had here and had no luck. According to the Powermac G4 support pages at Apple, this graphics card does not allow mirroring, so when I plug in the 2nd screen, nothing changes. "Detect displays" is still unavailabe on the system settings panel.

This is a bit disapointing, but obviously not the end of the world, as I didn't really expect to get the most spectacular computing experience in the planet when I got this 5 year-old Powermac from Ebay. It's just a test-drive that has gone well enough for me to decide on buying a Powerbook

The plan then changed to having the powermac work as my print/file/scanner server here at the office, and the Powerbook as the main workstation, connected to the big LCD when I'm there. trouble is the DVI interface still doesn't do anything! There is one relevant difference: the Powerbook is capable of showing the same desktop on 2 screens, so I'm not getting 100% blind when I plug in the DVI cable.

I'm using OS X Panther on both computers now. A couple of months ago, I tried installing Ubuntu Linux on the Powermac (which worked nicely) and the DVI connection was unavailable for that OS as well
It's kind of hard to believe that the screen or cables are faulty, especially as the Apple logo screen shows up at boot time, just for a few seconds so I can see that there is a significant difference between analog and digital input grrrrr!!!!

Nuno

 

[Makosuke]

trouble is the DVI interface still doesn't do anything! There is one relevant difference: the Powerbook is capable of showing the same desktop on 2 screens, so I'm not getting 100% blind when I plug in the DVI cable.

Wait, what PowerBook to you have? The PowerBook, assuming it can drive a monitor of that resolution via the DVI output (which it should be ablel to--I think even the earliest ones with DVI could handle somewhat higher than your monitor), should have no trouble at all running its internal screen plus the external one. Panther isn't quite as slick as Tiger about detecting displays you plug in after startup, but it should still work fine.

If you turn off the Powerbook, plug the DVI cable into the monitor and PB, then start up, I'm assuming you've got a working screen on the PB's built-in screen. At that point, if you bring up System Preferences, then go to Displays, does the Arrangement tab show up? If so then it's seeing your external monitor, it's just not displaying anything on it. You SHOULD be able to do a "gather windows" from there which will bring the settings window for the 2nd monitor over onto the working one, which you can then use to test various resolutions and see if you can get one working. Of course, if Mirroring is on, turn it off, so you can play with it.

If you're NOT seeing "Arrangement", and "Detect Displays" does nothing, then for some reason your monitor just isn't communicating via the DVI port with your Mac. Could be a rare incompatibility (they do exist, though I've never seen one in person), or perhaps it's just a bum cable. Tried it with either a Mac running Tiger or a Windows machine, to be sure?

 

[nplima]

eureka! (i think)

Hi again,


I've recently upgraded to Tiger, and could still not get any image on the HP LCD.
Today I went back looking for a solution, and re-read what HP has on their website about this screen. The DVI connector is of the "DVI-I" type (http://en.wikipedia.org/wiki/DVI) and my cable is of the "DVI-D" type.

the devil is in the details