Video problems with iMac G3 ATX

8 replies [Last post]
Offline
Joined: Mar 15 2005
Posts: 5

Hello,

I'm working on a project in which I'm converting an iMac G3 500 into an 19" rack server.
Everything is working so far, it boots up perfectly with an ATX-PSU attached and can be already accessed by vnc. The only problem I have is the video. Connecting a monitor to the soldered-on SubD-15 VGA port gives a weired picture, so I took the internal video cable and soldered a vga connector to it. If i connect a monitor to it, I'm getting a dark, blurry greenish picture. I can hardly see the top bar of OS X but can't read anything. Is this a known problem? Did I made anything wrong?

Thanks,
moongate

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Offline
Joined: Feb 6 2005
Posts: 34
What is your resolution and r

What is your resolution and refresh frequency?

Are your VGA ground wires OK and all connected together?

Offline
Joined: Jun 8 2004
Posts: 48
The refresh rate may be too high

Many of the iMac G3's used a very high refresh rate. I believe the default setting was 95Hz. Not many monitors can support this at a high resolution. I suggest VNCing in and lowering the refresh rate, if you can.

Thank you,
Chris

Jon's picture
Jon
Offline
Joined: Dec 20 2003
Posts: 2804
At almost any resolution unde

At almost any resolution under 1024x768 the refresh rate will be too high for most monitors. If you can get it to boot at 1024x768, everything should be peachy fine on the external port.

__________________

I am not in this world to live up to other people's expectations, nor do I feel that the world must live up to mine. - Fritz Perls

Offline
Joined: Mar 15 2005
Posts: 5
Thank you for your answers!

Thank you for your answers!
Is the iMac booting at 1024x768?
My problem is the booting screen and os x itself.
In os x the screen resolution s 1024x768 with (i guess) 75Hz.
Why is the picture so bad and unreadable?

Should I really connect all grounds of the connector together?
Also the 3 grounds of reg, green and blue?

Jon's picture
Jon
Offline
Joined: Dec 20 2003
Posts: 2804
Each of the R G and B line sh

Each of the R G and B line should have it's own ground. Don't tie them together. If there is a general GND use that for the other grounds.

__________________

I am not in this world to live up to other people's expectations, nor do I feel that the world must live up to mine. - Fritz Perls

Offline
Joined: Mar 15 2005
Posts: 5
Ah ok... This way i did it...

Ah ok... This way i did it...

Jon's picture
Jon
Offline
Joined: Dec 20 2003
Posts: 2804
It's a tad bit late to ask, b

It's a tad bit late to ask, but were there any video problems before you started the conversion? Does the machine have the latest firmware installed?

__________________

I am not in this world to live up to other people's expectations, nor do I feel that the world must live up to mine. - Fritz Perls

Offline
Joined: Mar 15 2005
Posts: 5
No, the video was perfect (th

No, the video was perfect (the builtin). I have never testet the externel connector.
I didn't manage my video problem yet but i have managed to install an OS half-blind Wink

By the way, if you are interested how my mac looks like: http://www.applefritter.com/node/7038