I have a new Raspberry Pi 2, at the first time it worked, but now the two ligths are on (green and red) but there no sinal on the TV.
This situation is clearly described in the Troubleshooting document in these forums. viewtopic.php?f=28&t=58151shafirdo wrote:When connecting power, the two light up together.
Regardless of whether a card is inserted or not.
And the system does not rise.
The ACT LED is essential in determining if the Pi can actually read from the card. If the ACT LED doesn't blink quickly in an irregular pattern for at least twenty seconds, this indicates that the Pi cannot read from the SD card, and that booting is not taking place. It doesn't matter if the ACT LED initially starts on or off. It is only the blinking of the ACT LED is significant. A dim ACT LED also has no significance beyond the fact that you are using a B. From the model B+ onwards, the LED is driven differently, and is brighter.
With no SD card inserted, note how the ACT LED behaves. Now insert a programmed card: that behaviour should change, and, if it does not, this indicates that Pi cannot see the necessary files on the SD card.