HDMI CEC Craziness

General Discussions
1

No related to plex but I thought maybe someone here could be helpful.

For reasons of using the shield pro for plex and complete tv control I have turned on cec

For some strange reason both of my TVs are doing odd things to the receivers. They are shutting them off switching inputs, etc.

Now this is important here, these are classic 2 channel receiver with IR control only. They have no video capability at all (not even a third rca video port for vintage electronics) they are hooked up to the TVs with 3.5 mm to rca cables from the TVs to the audio ports on the receiver. Seriously this is set up just like you would set a home theater system up in the 80s.

The TVs are different, LG and Samsung, the receivers are the same Sony two channel receivers from 2005. Just a basic receiver. Both sets do have NVIDIA shield pros and Xbox ones connected.

The shield and the Xbox are set to have IR blasting capabilities to control the receivers, however the receiver is behaving oddly even when both devices are off, shield has green light off and Xbox is 100% off. Example I turned the Nintendo switch on and turned the tv on and the receiver went off. Even running an update check on the Samsung tv shut the receiver off when the tv blinked off for a second.

Two changes I made that would be the culprit (turning on hdmi cec and adding the shield pros to my setup)

I’ve even put the shield remote in another room with the door closed so the Ir transmitter on it can be ruled out,

Either the shield pro has a hidden Ir blaster in the box itself or for some crazy reason the tv is actually able to turn off the receiver through its rca cables??? And I’m not sure why it always wants to change the state of the receiver when it should not be going off (like nobody who changes hdmi1 to hdmi2 would ever want their stereo to go off) the Xbox has also been unplugged.

Anyone have a clue or do I just have a ghost trying to piss me off lol

2

CEC can be a pain in the butt, many devices do not do what they are supposed to even when told.

just fiddle until you get something you are happy with.

CEC is designed to let devices interact with others (power states, etc), just know that everyone implements it differently. I found my XB1 to be quite unruly and often turn my TV off even when it was specifically set to NOT do this.

Ironically Nintendo devices seem to behave the best. which kind of blew my mind.

it’s all done via the HDMI cable too, not IR.

3

Do those receivers have an auto-off feature? It could be co-incidence that the instant you try to turn the TV on using the Switch, the receiver notices no input over a long time and turns itself off.

Alternatively, some devices give out an inaudible “noise” signal to prevent receivers from turning off for precisely this reason. If you turned the TV on via the Switch, the TV is swapping inputs. Even with the shield “off”, it’s still “on” passively sucking power… mostly to be able to boot up faster, but it could still be giving out this silent “noise” signal. So when the TV turns on (even THAT was probably half-on, listening to the HDMI port for a CEC signal, while hearing the silent “noise” from it) and swaps input, suddenly there is ZERO sound from the switch (doesn’t have this capability), and the receiver turns off from zero input.