Chosen Solution

Dear everyone, I am from China, just got a cheap iMac G5 logic board from a dead 20" model(A1145), I am trying my best to get it work again, I have modified 2 heat sinks to get them fit the original heat tube place. now the biggest problem how to power the board with a ATX PSU, I have googled for some while but with no luck, all I can find is how to power a first generation G5 with a ATX(http://jimwarholic.com/category/imac_g5), but the iSight model uses a different PSU, only 5 wires are out from the PSU, the 5 wires go into the inverter board, then 14 wires to the logic board. The pinout of the 14-wire connector is: Group 1: INV_CPU_HI SYS_POWERUP_L_BUF PP12V_ALL PP12V_ALL PP5V_ALL PS_GND PP3V3_ALL Group2: LCD_PWM POWER_GOOD PS_GND PP12V_RUN PS_GND PP5V_RUN PP3V3_RUN I presume the LCD_PWM is used to adjust the brightness of the LCD back light, but what are the “INV_CPU_HI” and “SYS_POWERUP_L_BUF” pins for? any help will be greatly appreciated! :)

why did you bother about the 14 pins ? - if you still have the 5 pin connector you only need to worry about the 5 pins ;-) i’ve found the pinout on insanelymac: Grey: +12V Grey: +12V Black: ground Black: ground Brown: PFW (battery powered signal between +3 and +6.5 volt to switch power supply on)

Thanks Markus, that is the old model, the PSU directly connected to the logic board, in the iSight model, there is a DC-DC board between the PSU board and the logic board, and the P1 connector is only 14pins. Anyway still thanks for your post :) cheers

  • Eric

Hi, I guess SYS_POWERUP_L_BUF may be the ATX PS_ON ! Did you find more clue ? I have an Intel iMac LogicBoard and i would like to bring it back to life too ! Thanks

In fact on my iMac Intel 17" logicboard there’s only have 12 pins. I guess 20" needs INV_CPU_HI and LCD_PWM but 17" doesn’t. PP12V_ALL ALL for “always” on. PP12V_RUN RUN for when PSU is on. But PP12V_ALL and PP3V3_ALL can’t be provided by an ATX PSU (there is only the PP5V_ALL) PS_ON | PG 12V | GND 12V | 12V 5VSB | GND GND | 5V 3.3V | 3.3V doesn’t work !