Ask Max: G4 iMacs won't turn on with ADC monitors attached...
We are a small nonprofit agency in Charlotte, NC, and about 18 months ago a local college donated to us a set of four PowerMac G4 towers and 3 17-inch Studio Displays. Everything worked great until a couple of weeks ago when, within 12 hours of each other, two of the G4s would not turn on unless we disconnected the displays and hooked up a non-ADC monitor. We can't tell if the problem is with the towers or the monitors. We have one G4-ADC combo that is still working, but the "sick" G4s won't work if I hook up the working monitor to them. I tried to use an DVI to ADC adapter, thinking that it might help if the issue was the inability of the monitor to pull sufficient voltage through the ADC cord, but that didn't work.
Any ideas? I'd hate to think that the monitors were no longer usable, since they seem to be in good shape.
Well the first step in troubleshooting a ADC monitor is to remove and then reinstall the video card. Believe it or not just reseating a video card can help. I assume these are LCD based Apple 17" Displays, if they are CRT displays, then there are a host of issues that follow the CRT models. First the CRT models will not run off DVI to ADC adapters, and second the CRT models draw so much power it can be under powered on on many ADC video cards.
If the problem is with the LCD ADC display, then it may be a USB problem inside the display. When using the DVI to ADC converter, try not connecting the USB plug to see if that has any effect. Also make sure the computer is directly connected to the wall outlet. That should eliminate under powering issues.
Let me know how that works out,