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Model A1225 / Early 2009 / 2.66, 2.93, or 3.06 GHz Core 2 Duo processor

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Power Supply pin (voltage, start other?)

Hello,

I would like some insights about iMac's power supplies, especially the Early 2009 24" (A1225 EMC 2267).

I decided to tinker with an old broken iMac (machine that shuts itself down) to make it a Media Center with my Rasberry Pi and its Hifiberry + an LCD controller. But to do it right, I need to use the power supply for the screen (+ fan and why not also power the raspi).

But for that, I need two things:

The voltages (and current) of the output connectors which are obviously not standard (12 pins for the 12v-3.3v and 12 pins for the 24v that runs towards the inverter of the screen, although for the latter, I don't really care).

Know which pins to connect to activate the power supply (if I had this element, I could measure the voltages myself).

For now, I've spotted three things:

* Pin 1 = Ground

* Pin 2 = 12v always on

* Pin 4 = 3.3v always on

* Pin 6 = Ground

For the rest, I'm drying up, if you'd give me a hand, I'd be extremely grateful.

Update (08/09/2019)

Hello,

I've made some progress in my tests, I've managed to activate the power supply!

It is sufficient to make a bridge between the ground (PIN 1,6,7,12) and the 3.3V (PIN 4), which activates pins 8, 9, 10

So we end up with these values:

On the 12V output (2x6 pins)

  • Pin 1 = GND
  • Pin 2 = 12VDC -> Always On
  • Pin 3 = GND -> if SATA connected
  • Pin 4 = 3.3VDC -> Always On -> PS_ON
  • Pin 5 =?
  • Pin 6 = GND
  • Pin 7 = GND
  • Pin 8 = 12VDC -> If On
  • Pin 9 = 12VDC -> If On
  • Pin 10 = 12VDC -> If On
  • Pin 11 =?
  • Pin 12 = GND

On the 24v output (1x12 pins)

  • Pin 1 = 24VDC -> Always On
  • Pin 2 = 24VDC -> Always On
  • Pin 3 = 24VDC -> Always On
  • Pin 4 = 24VDC -> Always On
  • Pin 5 = 24VDC -> Always On
  • Pin 6 = GND
  • Pin 7 = GND
  • Pin 8 = GND
  • Pin 9 = GND
  • Pin 10 = GND
  • Pin 11 =?
  • Pin 12 =?

A last connector is present on the power supply, it is a ground that seems to be dedicated to the 5V (it is connected to one of the SATA GNDs and to the motherboard).

We can see that this power supply only provides 12V and 24V, as surprising as it may seem, it is the motherboard that is in charge of transforming the 12V into 5V! (the cable between the power supply, the motherboard and the hard disk confirms it).

So I still have Pin 5 and 11 on the 12V port and Pin 11 and 12 on the 24V port which are a mystery (if someone has an idea, I'm a buyer)...

I found the electrical schematic of a Liteon PE324101UN-LF power supply (which also seems to be used in other iMacs), there seems to be some info, but I can only guess the usefulness of these pins....

On the 12V output (2x6 pins)

  • Pin 1 >>- +12V
  • Pin 2 >>- +12V
  • Pin 3 >>- +12V
  • Pin 4 >>- GND
  • Pin 5 >>- GND
  • Pin 6 >>- GND
  • Pin 7 >>- +5VS
  • Pin 8 >>- +5VS
  • Pin 9 >>- +5VS
  • Pin 10 <<<- AC_DET (Alternating Current Detection?)
  • Pin 11 <<<- P_DIM (Power DIMming?)
  • Pin 12 <<<- BL (LCD BackLight?)
  • Pin 12 <<<- PS_ON (PowerSupply ON !)

On both 24v outputs (1x12 pins)

  • Pin 1 >>- 24V
  • Pin 2 >>- 24V
  • Pin 3 >>- 24V
  • Pin 4 >>- 24V
  • Pin 5 >>- 24V
  • Pin 6 >>- GND
  • Pin 7 >>- GND
  • Pin 8 >>- GND
  • Pin 9 >>- GND
  • Pin 10 >>- GND
  • Pin 11 <<<- P_DIM (Power DIMMING?)
  • Pin 12 <<<- BL_ON (BackLight ON?)

For AC_DET, I found this definition:

AC adapter voltage detection input. Valid AC adapter input range is set using resistors forming a voltage divider which are connected between ACDET & GND and ACDET & AC adapter.

P_DIM should reduce the output power of the 24V PINs to reduce the brightness of the display?

BL_ON, turn on the LCD?

In short, full of new questions.

Update (09/09/2019)

Well, I finally succeeded in measuring everything I wanted.

I made a little schematic for those who would be interested.

If there's a mistake, don't hesitate to tell me.

Block Image

oldturkey03> BL_ON needs to be powered in 5v to turn on the screen. For P_Dim, it's more complicated, I think it's about frequency, but the LCD converter will do it.

mayer>My power supply works very well, it is here a question of knowing what its specifications are to power a Raspberry Pi and other accessories without Apple motherboard! ;)

Answer this question I have this problem too

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Comments:

@mrsoul I got totally lost with your measurements. Which connector(s) are you looking at? BL_On only turns your backlight on not the LCD. P_Dim seems to be high at 24V Post some pictures of what you measure where Adding images to an existing question

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1 Answer

Most Helpful Answer

If you ever get tired of trying to fix this, get a new one here for $50- $60 :

240W or 250W Power Supply for Imac 24" A1225 PA-3241-02A ADP-250AF ADP-240AF 661-4995 614-0416 614-0432,MB418;MB419;MB420

https://www.aliexpress.com/item/32808725...

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MrSoul will be eternally grateful.
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