Powermac G4 G-E adc problem

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applemiga Author

Level 1

0 points

Powermac G4 G-E adc problem

Hello

i'm new to this community and new to using apple computers.

i picked up a rather cheap apple powermac G4 450MHz to fiddle around with.

it came with a keyboard and a CRT-monitor (a heavy and tranparant housed crt) with ADC connector.

the thing is i have to use the power button on the crt monitor to power up the system , without the adc monitor the system won't power on.

the power button on the system case does not seem to be working .

i wanted to try running MorphOS on this computer .

i connected a second monitor to the VGA output on the video card (agp rage-128 pro)

the apple monitor doesn't accept the screen resolution for morphos and it works fine on the vga

morphos or Os-x , i'd like to power up the g4 without the adc monitor because it uses way to much space , any ideas?

i could hard wire the trigger signal on the psu 🙂 but it should be working without .

regards

Posted on Feb 11, 2015 12:26 PM

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Answer 1

BDAqua

Level 10

239,435 points

Feb 11, 2015 2:40 PM in response to applemiga

Hello & welcome! 🙂

It should work, but that's a fairly common problem with MDDs & QS G4s, generally bad Logic Board, or PSU, but occasionally due to the button being offset & catching wrong, or the circuitry behind it bad.

5 volts not getting through somewhere... Maybe a switch on the ADC port?

http://pinouts.ru/Video/apple_adc_pinout.shtml

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Answer 2

pe2ek

Level 1

0 points

Feb 12, 2015 12:16 PM in response to applemiga

Ok the same guy as Applemiga here i did something wrong with the main e-mail adress and i couldn't change it , so i made a new account.

anyway thanks for the answer BDAqua , i fiddled some more . i booted the powermac and Hot un-plugged the adc monitor , the system keeps working and there still is a view on the vga monitor , so i think that that means the PSU is ok . When i select reboot the sytstem reboots when i select shut down it shuts down but i can't get it up because the power button doesn't work.

i disassembled the pcb with the reset interrupt and the power button ,

there is a IC on it wich looks burned in fact there is a hole in it.

i'm looking in the service manual for the pinout of the pcb cable may be it is just a pulse to start , i can give it a start pulse with the mutlimeter on amps and see if the system comes up.

if it is only the button pcb ik could be a simple repair .

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