Retropie working on one TV but not another

Ballardian

I set up a Pi2 B with retropie the other night on my main TV in the living room. Everything went fine. Had a bit of a play.
Next day, I brought it into the other room and connected it to a different TV to add some more stuff. Again, everything went fine.
That night, I brought it back into the living room so the kids play some games. Plugged in, red and green lights were solidly on, but nothing else. Plugged it back into the other TV, green flickering light, booted up and it was still working fine.
I tried forcing HDMI in config.txt to no avail.
Just now, I reinstalled retropie and plugged it straight into the main TV. Nothing. Just constant red and green lights, no activity.
Any ideas, before I pull my hair out?
Thanks

mediamogul

@Ballardian

Are you using the same power supply between the two locations?

Ballardian

Yes exact same setup even the same HDMI cable.

TMNTturtlguy

@Ballardian not sure others can replicate this, but I have the same issue on a few TV's. What I found is I have to make sure I have the raspberry pi connected to the tv via hmdi prior to powering up the pi. If i do this, it works perfectly on every TV. If I power up the pi before the hmdi is connected, I am unable to get the TV to get the signal. Have you tried this?

AlexMurphy

@Ballardian post the contents of /boot/config.txt Use code blocks to format or it won't make sense. That is 3 back ticks in the line above and below the file text.

IT WILL
THEN LOOK LIKE
THIS

Ballardian

OK so after a bit of fiddling about, it now works, kind of.
I connected a switchable HDMI hub to the TV. If I have the hub preset to where the Pi input is, nothing happens.
If I have the hub set to any other input, and then power the Pi on, the hub switches to the correct input, the Pi boots and everything is fine.
I have tried this a couple of times so it's repeatable. Seems like I have a workaround but I'm scratching my head as to why it would be. Surely if the HDMI line to the TV is already in place, it should just boot up?

Ballardian

Also I managed to get a nice little shock during said fiddling. Serves me right I supose.