Mac wont start if ADC is not Connected??

Question

Level 1

0 points

Mac wont start if ADC is not Connected??

I have a G4 Quicksilver Dual processor, with Tiger OSX installed on it. The video card installed has a ADC and VGA connector. I recently wanted to change from the ADC monitor to the VGA(new PC Monitor). But when the apple display is not plugged in the computer wont start.

Why

I have done all the system preference stuff and changing secondary to primary and even swapped video cards with another machine which i know works with the VGA connection.

Please Help

Cheers

PowerMac, Mac OS X (10.4.11)

Posted on Jun 15, 2011 12:11 PM

Reply

Answer 1

Best reply

BDAqua

Level 10

239,363 points

Jun 15, 2011 12:51 PM in response to brownsource

I had that problem on two different MDD G4s, one was the Logic Board, other was possibly the PSU. 😟

I think it means the voltage needed to start up is bled back thru the monitor to the Logic Board.

On one an old USB Keyboard that had the Power key on it worked to start it without the ADC monitor.

Reply

Answer 2

brownsource Author

Level 1

0 points

Jun 15, 2011 2:39 PM in response to BDAqua

Cheers for reply but how do i fix or get round this problem

Reply

Answer 3

brownsource Author

Level 1

0 points

Jun 15, 2011 2:58 PM in response to brownsource

Would it be possible to just needing to replace the graphics card

I'm at my wits end on how to fix this - please help

cheers

Reply

Answer 4

BDAqua

Level 10

239,363 points

Jun 15, 2011 3:10 PM in response to brownsource

I do not believe it's the Graphic Card, I think it would need either a new Logic Board or Power supply.

Which card is it exactly, some can run both monitors at once.

And there may be a slight possibility that a Keyboard like this with a "Power Key" at the top right corner may work to start it...

http://tinyurl.com/5s28kla

Reply

Answer 5

brownsource Author

Level 1

0 points

Jun 15, 2011 3:17 PM in response to brownsource

Also if i unplug the adc monitor while computer is on the VGA works absolutely fine and even after i have detected monitors in the system preferences it all looks great but as soon as i shut machine down it wont start back up without the ADC attached gggggrrrrrrrrr.

WHy

please reply to this as i am in turmoil

ta

Reply

Answer 6

BDAqua

Level 10

239,363 points

Jun 15, 2011 3:26 PM in response to brownsource

I believe it's not getting the 5 volt trickle/startup voltage to the Logic Board unless the ADC Monitor supplies it.

Have you checked the PRAM Battery, they can cause strange things & last 4+5 years or far less if no AC is supplied?

http://eshop.macsales.com/item/Newer%20Technology/BAA36VPRAM/

Reply

Answer 7

brownsource Author

Level 1

0 points

Jun 15, 2011 3:42 PM in response to BDAqua

i will change it and let you know how i get on - thanks for all your time

C ya

Reply

Answer 8

brownsource Author

Level 1

0 points

Jun 17, 2011 5:39 AM in response to BDAqua

I gotta say a mighty thank you for your(BD AQUA) Help even thought the things you were saying were kinda over my head a bit, it made me make the advance of changing the power supply and it totally worked...........

I guess my power supply was NOT giving out enough juice to get it started

THANKS AGAIN ITS MUCH APPRECIATED

Reply

Answer 9

BDAqua

Level 10

239,363 points

Jun 17, 2011 9:28 AM in response to brownsource

Great work, great to hear, thanks for the report! 🙂

Reply