Hi,
In your section : APM 2.5 and 2.6 Overview…APM 2.6
You describe that the new APM 2.6 does not have an on-board compass BUT then in you photo you have a big arror pointing to the “MAG”
This photo seems to be actually of a V2.5.2 board …Is that right.
Do you have a definitive photo of the APM 2.6 board 
Thanks
I have got the 2.6, and I have seen that the slot for the magn sensor is empty, it hasnt been soldered.
I did some magic trick to use my old one from APM 1 without the connector: solder 4 wires + make a nice hole 
@max246,
Who did you purchase your APM2.6 from? Was it 3D Robotics or a third party vendor? There should have been a 4 pin socket on the APM2.6 for the compass I2C cable. Very strange to say the least!
Regards,
TCIII Admin
Well I had to attach old compass so I couldn-t wait a few days before the cable arrives at my house, so I just did it on my way 
After I got the cable I just remove my temp fix and then I hooked it up with the cable