Power issues with arduino uno and eth Shield

Projects Networking, Protocols, and Devices
1

Hello everyone I have encountered this problem with:

Arduino uno and eth Shield.

case 1) if the power is supplied by USB, the arduino and eth shield work currectly

case 2) if the power is supplied by External Power (12V) the green led on arduino is ligth on, but eth shield
doesnt work: the PWR led is red and the other led TX, RX, etc are ligth off and. If i plug the eth cable I dont see
that lights blink (in eth port).

i have already read:

http://forum.arduino.cc/index.php?topic=22385.0
http://forum.arduino.cc/index.php?topic=22385.0

can someone suggest solutions???

2

If i plug the eth cable I dont see
that lights blink (in eth port).

You don't see what lights blink?

The RX and TX LEDs on the Arduino are controlled by the USB to serial chip, not the Arduino.

3

No, i dont see the led TX, RX, COLL,FULL, 100M and the led in rj45 port

4

Try a 9v wall wart.

5

I will keep you updated

thaks