I only want to confirm the real solution is THE USB connector . I just did it a minute ago.
I divided a USB cable into two pieces. Stripped the wires on both sides, because I liked to know which wires I needed for the 5 volt.
I my case, it was the red and the black wire. Checked the 5 V (4,81 V ) on the computer side (MAC) so I knew which wires I I had to connect at the USB connection, direction Arduino .
The 5 Volt (5,64 V) from an external pc power supply was enough, because on the USB entrance of the arduino there is a diode in serial . I did have the time to measure the 5v on the arduino, because I liked to tell you this.
Thanks for the idea. I works!