[G4] Using ADC graphics card in Sawtooth G4

[Derek Heeps]

Hi ,

I have a G4 450Mhz AGP graphics 'Sawtooth' Powermac , currently with  
the ATI Rage 128 graphics card which has VGA and DVI connectors .

  Just the other day I bought an Apple 15" LCD display with the ADC  
connector as they are now very cheap on eBay. I also bought an ATI  
Rage 128 Pro graphics card with VGA and ADC ports .

On installing the card I found that the VGA port worked but the ADC  
did not . On further investigation , I discovered that I was missing  
the 24V supply to power the monitor , since my motherboard does not  
have the connector to mate with the extra tag on the board .

I presume , however , that rather than blow £70 on the Apple DVI to  
ADC converter (which I know will work with my old graphics card) ,  
all I have to do is connect a 24V power supply to the unused tags on  
my graphics card . Has anyone ever done this , and does anyone know  
the polarity of these tags ?

I have found the pin assignment for the ADC connector on a number of  
websites , so tonight I will try metering from the power pins back to  
the tags to see if I can work it out that way .

I have a spare 24V power supply from a dead iBook which can deliver  
around 2A , don't yet know if this will be enough to run the  
15"screen ; I have seen a requirement of 4A posted elsewhere but  
guess this may be to drive some of the larger screens - I'll try it  
tonight and see what happens and will post back my findings - the  
worst that can happen is the power supply will expire . I can always  
build a bigger one , but the idea is to do this on the cheap . Can I  
pick up 24V , 4A anywhere inside the machine ? I also have a dead G4  
tower (faulty motherboard , possible project)  with a good power  
supply but have not investigated what is available here .

Just wonder if anyone has done this before and with what results ?