Mac G4 450 AGP LCD VGA monitor problems

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Level 1

80 points

Mac G4 450 AGP LCD VGA monitor problems

Not sure where to start here....but, i have a G4 450 AGP Mac, with ATI Rage 128 Pro video card (VGA and DVI)...for the last couple of years used an Apple Multisync 20 CRT monitor.

I recently purchased a Gem (scanport) GL-1821A 18" LCD VGA flat panel monitor. The basic problem is the monitor won't display graphics on start up past the "apple boot screen".

However, if I start the G4 plugged into an old Compaq 7500 CRT monitor until start up and then unplug the CRT and plug in the LCD, the LCD works just fine. The LCD simply won't display from start up.

I tried looking for new ATI software and ended up with a utility... 'ATI Displays Control Panel version 4.5.7'....which shows the Compaq 7500 (when the CRT is hooked up), but not the LCD.

I have tried Auto-Adjust, setting the resolution/refresh but nothing.

BTW, the LCD starts in OS 9.2.2 boot at the lowest resolution (620x480, or something like that) and i can change it the desired 1152x670 from the control panel. So, if it starts in 'classic OS' why not 'OSX'

I have not seen this before....VGA to VGA...just plug in and go...any ideas would be appreciated...thx

Dave

Mac G4 AGP, PB G3 Bronze, PPC G3 Biege Mac OS X (10.2.x)

Mac G4 AGP, PB G3 Bronze, PPC G3 Biege Mac OS X (10.2.x)

Posted on Jul 3, 2006 3:57 PM

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Answer 1

PB PM

Level 4

2,480 points

Jul 3, 2006 4:35 PM in response to David Raye

Try booting OSX in safe mode (hold "S" key at boot). The monitor may not support same screen resolution that the old monitor was set to, which could cause what you are seeing.

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Answer 2

David Raye Author

Level 1

80 points

Jul 4, 2006 2:44 AM in response to David Raye

Some more info...i will keep this consise:

Tried the 'safe boot' with the same results (flat panel did not start in OSX)

G4-AGP runs OSX 10.2.8 and 9.2.2 'classic':

1 - When starting in OSX the G4 starts my Apple 17" Studio Display (VGA CRT) and my Compaq 7500 (VGA CRT) but not the GEM Flat Panel (VGA)
2 - When starting in OS 9.2.2 the G4 starts all three monitors as it should...proper resolution

My G3 biege (OSX 10.2.8 and 9.2.2, with ATI Mach 64 Pro video card) will start the Compaq 7500 (VGA CRT) and the GEM Flat Panel in both OSX and OS 9.2.2 (It won't start the Studio Display in OSX or OS9)

So, bottom line: The G3 starts the flat panel in OSX and OS9. The G4 starts the flat panel in OS9 only. Both computers have the same OS configuration and the G4 supposedly has 'better' video card.

Not sure any of this is helpful....seems as though there is some issue with the G4 OSX-ATI card combo

Dave

Mac G4 AGP, PB G3 Bronze, PPC G3 Biege Mac OS X (10.2.x)

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Answer 3

PB PM

Level 4

2,480 points

Jul 5, 2006 12:11 AM in response to David Raye

What is the native screen resolution of that 18" screen (thats an odd size)? Its possible the card does not support the screens resolution. Just because its a newer card, does not mean that it supports the same screen resolutions.

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Answer 4

David Raye Author

Level 1

80 points

Jul 5, 2006 2:42 AM in response to PB PM

well...i'm not sure about the native screen resolution....

when it does not start in OS X on the G4, after the boot screen and it goes black. I can press the 'menu' button and it shows 1152 x 864 119.8Hz/96.7KHz.

What puzzles me is that i can start the LCD on the G4 using OS9. And my G3 will start it using OSX and OS9. Both machines have same versions of OSX (10.2.8) and OS9 (9.2.2).

If the G4 starts the LCD in OS9 why not in OSX?

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Answer 5

David Raye Author

Level 1

80 points

Jul 5, 2006 11:01 AM in response to David Raye

OK...Here's what i found

Hooked up my Sony SDM-S81 flat panel to the G4...everything works fine. Hooked the Scanport GL-1821A to my PC...everything works fine.

Have no idea why the G3 in OSX starts the Scanport but the G4 in OSX does not. Could there be something missing in display detection in the G4 OSX system libraries?

Anyway....I have everything working....

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Answer 6

PB PM

Level 4

2,480 points

Jul 6, 2006 8:13 PM in response to David Raye

The Rage 128 Pro does not support that screen size at 96Hz... that could be the issue. At that resolution it can only support 75Hz. OS9 would boot most likely because its a bit more flexible and impose the resolution you noted in your first post. OSX on the other hand will do what you are seeing if your machine is not using a support resolution.

Here is an idea, with the working monitor set the resolution to 1152 x 864 at 75hz, (this information is saved by the OS and will effect any monitor you hook up) hook up the new monitor and see if that helps.

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Answer 7

David Raye Author

Level 1

80 points

Jul 6, 2006 8:39 PM in response to PB PM

Thx everyone for the ideas...btw, I have tried 'forcing' the resolution, as well as trying several different res/refresh combos....the G4 in OSX simply doesn't like this monitor....lol. And, like i said the G3 will start it in both OS's. I will simply run my Sony monitor on the G4.

Still puzzling though why the G3 will run it and the G4 will not. Both have 'same' OS's

Again thanks

Dave

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