External display problems

P

Paul Goldsmith

Registered
Hello,

I hope someone might be able to help. I used to really enjoy the fact that, comapred to PC colleagues, when I plugged my powerbook (550Mhz, with ATY, Rage M6, running 10.3.4) into an LCD projector for presentations it would always automatically configure. I then tried to mirror it to an external LCD screen in another Department, which failed, and then ever since then I have not been able to get external displays to work.

The system seems able to recognise the external display, as it comes up with the correct manufacturer, but nothing comes up on the external display. With one display (another TFT screen), if I manually alter the resolution and frequency then I can see something, but all fuzzy.

I have tried resetting vram, but this has not helped.

Any thoughts ?

Thanks

Paul
 
Zammy-Sam said:
Are you using the "Detect Screen" button in System Preferences -> Screen?
Click to expand...

Yes. It does seem to recocgnise the external monitors, as it titles the options list of frequencies and resolutions with the correct name, but nothing projects, and the monitor registers as 'no signal'
 
Flat-panel displays have what is known as a "native resolution" to them. This is the only resolution that will display clearly, and use each pixel in a 1:1 ratio. If you use any resolution other than the native resolution, then you'll see a fuzzy image, simply because the monitor is trying to display pixels that are larger or smaller than the ones native to the monitor. For example, a flat-panel display that has a native resolution of 1024x768 (most 15" flat panels) will display 1024x768 clearly -- however, if you change the resolution to 800x600 or something like that, the image will be fuzzy because the monitor has to use more than one pixel to display each pixel, if that makes sense...

Are you sure you're trying to display the image at the native resolution of the monitor? What monitors are they? After you find out what the native resolution is, set it, then play with the refresh rates. LCD displays usually don't have refresh rates, but for the sake of compatibility and such, they are allowed to be set -- usually at 60 or 70Hz.
 
It is now a problem with all external displays - a TFT and 3 different LCD projectors. The LCD projectors I now get diddly out of, but the TFT at least I can get something if I play around with settings manually. Up until a week ago everything worked very sweetly on all of these displays.




ElDiabloConCaca said:
Flat-panel displays have what is known as a "native resolution" to them. This is the only resolution that will display clearly, and use each pixel in a 1:1 ratio. If you use any resolution other than the native resolution, then you'll see a fuzzy image, simply because the monitor is trying to display pixels that are larger or smaller than the ones native to the monitor. For example, a flat-panel display that has a native resolution of 1024x768 (most 15" flat panels) will display 1024x768 clearly -- however, if you change the resolution to 800x600 or something like that, the image will be fuzzy because the monitor has to use more than one pixel to display each pixel, if that makes sense...

Are you sure you're trying to display the image at the native resolution of the monitor? What monitors are they? After you find out what the native resolution is, set it, then play with the refresh rates. LCD displays usually don't have refresh rates, but for the sake of compatibility and such, they are allowed to be set -- usually at 60 or 70Hz.
Click to expand...
 
Are you "hot-plugging" these monitors/projectors into your PowerBook? It's not recommened to connect/disconnect displays to your computer while it's on. What happens if you turn off the PowerBook completely, hook up the monitor, then power back up?
 
ElDiabloConCaca said:
Are you "hot-plugging" these monitors/projectors into your PowerBook? It's not recommened to connect/disconnect displays to your computer while it's on. What happens if you turn off the PowerBook completely, hook up the monitor, then power back up?
Click to expand...


Yes, I've always hot-plugged. Will try a cold connect with the TFT, and if that works with the LCD projector at work tomorrow.
 
Ah, yes, I would try that. I know that DVI ports have a "hot-plug detection" pin, but I've never owned a DVI monitor, and from what I remember with VGA connectors, hot-plugging them is highly advised against.

I hope that works for you!
 
Unfortunately makes no difference. Any more ideas ?


ElDiabloConCaca said:
Ah, yes, I would try that. I know that DVI ports have a "hot-plug detection" pin, but I've never owned a DVI monitor, and from what I remember with VGA connectors, hot-plugging them is highly advised against.

I hope that works for you!
Click to expand...
 
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