2008 iMac 20in power Distribution information

[Richdave]

I have taken some measurements from my PSU and since I have not seen this sort of info posted anywhere else and it is not in the service manual I thought I'd share it here.

refer attached

Note ** The voltage on pin 4 varies according to the temperature of the PSU and ranges between 1.7V and 2.5V - Higher voltage = lower temperature.

Hope that someone finds this useful

 

[Phantom Gremlin]

Hope that someone finds this useful

I won't find it useful, since I'm not about to disassemble my iMac.

But that's what's great about MacRumors. I'm sure there are many people here who will find your information useful.

 

[Richdave]

PSU wiring loom

I have put together some info on the PSU wiring loom too.

All care taken, but no responsibility if I have made an error. Use at your own risk

Pin 1 on the PSU is assumed to be the pin with the DOT indicator on the PCB - refer first post

Pin 1 on the Inverter connector has a Δ pointing to it

Pin assignment for the MLB connectors are assumed to conform to the "Molex" pin assignment convention. I could not see any indicators or markings on the MLB or associated connectors to confirm this though. - EDIT The solder side of the board has a square pad for what I believed to be pin 1 so I am more confident that I have it correctly assigned

The HDD SATA power pin-out details can be found HERE