Video problems with iMac G3 ATX

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Video problems with iMac G3 ATX

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

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Last seen: 12 years 11 months ago
Joined: Feb 6 2005 - 09:30
What is your resolution and r

What is your resolution and refresh frequency?

Are your VGA ground wires OK and all connected together?

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Joined: Jun 8 2004 - 15:14
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
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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.

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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
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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.

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

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

Jon
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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?

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Last seen: 13 years 1 month ago
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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

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