My Vizio Tv had an update. Ever since, my Roku stick will not work. It is the type that gets its power via a usb that also plugs into the tv. Tv shows "No signal". I have unplugged everything including the tv, let them sit a bit then plugged everything back in. Roku stick does not work on the other tv either.
Expanding on @renojim's reply, a couple of points relating to using the TV's USB port as the power source:
If the USB port powers down with the tv, as most do, that means the Roku has to startup every time you turn on the tv. During the TV's startup process it checks the HDMI ports to see what's connected. If the tv powers up before the Roku has started up to the point it can respond to the HDMI check, the tv will not realize there is anything connected to that HDMI port, resulting in a "no signal" report. If this is a new problem, it could be that a tv update caused the tv to start up quicker than before, or a Roku update caused it to start up slower than before, or both.
If the above is really the cause of the problem, as a work-around, try switching your tv to a different input then back to the HDMI port to which the Roku is connected. This will force a new check of the port and the Roku signal will be displayed.
The USB ports on some televisions only supply 0.5 amp or less, which is not enough to power a Roku reliably. A Roku connected this way often appears to start up normally, but if it runs into an activity that requires more power than the USB port can deliver, something will fail, commonly taking you back to the Roku home screen. Again, if this is a new problem, it could be caused by an update to the channel, the tv, or Roku software that causes the Roku to require more power than before from a USB port that was barely adequate to begin with.
The permanent solution in either case is to power the Roku, not from the TV's USB port, but from house power via the USB power adapter that came with the Roku. If you don't have the Roku adapter handy, any other you have from another device should work as long as the fine print on it says it outputs at least 1 amp.
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