820-00609 - iMac error SMC PFM006

[Palhano]

Hello friends,

I have this iMac 27 2017, it turns on, but with cooler at maximum and slow. Apple test software finds SMC error code PFM006.

Board has no signs of oxidation or short. Any lights to start?

 

[2informaticos]

Any history available?
Did the problem appear after machine was dissasembled?
Check if LCD temp sensor is properly connected.

 

[Palhano]

No problem history!

iMac has never been repaired! I used HWMonitor, noticed "high temperatures" in some sensors, memory, PCH Die, Ambient.

 

[2informaticos]

So many errors can only appear if the communication bus is blocked; not a problem from a particular sensor.
Try first disconnecting webcam cable.

 

[Palhano]

Same thing without the webcam.

I used TechTools Pro, didn't find any sensor errors.

 

[2informaticos]

HWMonitors shows the same temps like before?

 

[Palhano]

Yes, nothing has changed in HWMonitors.

With cooler on full and slow.

 

[2informaticos]

The closest schematic/boardview available is probably 00134.
Considering it as repair guide, you have a problem on U5650 area; search for it close to GPU power supply.
Check its solders, traces and R5650-52.

 

[Palhano]

Complicated when there is a schematic of the model! U5650 does not have or the chip is different. But I'm following logic to check the lines!

 

[Palhano]

Thanks a lot for the help!

But the customer was urgent, he chose to change the license plate in the authorized one.