does Chromecast have a built-in screen saver or auto power-off?

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http://forums.androidcentral.com – I left my Chromecast plugged in with nothing playing. The screen just shows the "ready to cast" graphics. Two hours later, it was still showing the same thing. My phone and tablet were both powered off at the time. I imagine it can't be too good on my old TV with no built-in screensaver. :( (HowTos)