My 10 year old TV Is getting harder to turn off..

chrisw

To check the remote itself, look at the end led through a camera such as on your phone. When you press a button on the remote you should be able to see the led flickering red. Make sure it does it with the power button.

flaneurs_lobster

That's interesting, why with a camera and not the naked eye? Is the camera doing some kind of frequency shift?

[Deleted User]

flaneurs_lobster said:

That's interesting, why with a camera and not the naked eye? Is the camera doing some kind of frequency shift?

No frequency shift, just the filters allowing IR light through.

Digital camera sensors are colour blind. They don't work like the human eye which has 3 primary colour sensitive parts specifically for red, green and blue frequencies.

Instead, digital camera sensors are just sensitive to photons of light regardless of colour / frequency and they pick up a wider range covering both UV and infrared that humans cannot see, as well as visible light we can see.

The trick that cameras do is to have a dyed filter in front of each of the millions of light sensors (pixels) which is either red, green or blue, and therefore each sensor will "see" red, green or blue passing to it, but it each sensor has no idea what that colour is. It is just a photon of light as far as the sensor is concerned. Computer processing then decides what it should do with that based on the filters assigned to each sensor and the number of photons detected (brightness).

These filters however do allow some infrared light through, in fact the infra red is picked up by all 3 of the RGB filtered sensors and so it appears more of a purple colour because sensors under the red, green and blue filters are all being triggered by infrared.



Most cameras do have infrared filtering (and UV), but it isn't enough to exclude all IR and in the case of really "bright" sources such as the remote control, it passes some through the filter - maybe as little as 10% of the IR gets through, but it is enough as shown in the photo above.

If our eyes could actually see IR, then looking at a remote control would appear like dazzling bright LED flashing away.

Here is the frequency response of a camera sensor vs human eye - the narrow green line is human eye, grey line for comparison is a standard camera.

For reference UV is on the left from 200-400 on the axis and infrared is to the right, 700 -1000.

flaneurs_lobster

Most interesting (and useful) thing I've learnt this week. Thank you@Deleted_User 

another_casualty

Well , I'm back ! 😼
I haven't had time / inclination to find other remote . However,  I just took the above advice from @chrisw and here is update as to what's going on now ..

While looking on the remote , I notice a very faint red emision which tells me the remote is still working . The light is not very powerful as in the pic above of @[Deleted User].
Bizarrely when pressing the remote buttons awa from the  tv  and while the iPhone camera was above it , the remote did every command immediately ! 

When I point the remote to the wall opposite the tv , again the remote works flawlessly !
When pointing the remote at the tv it now seems to work fine , testing it as I type this.
over the last couple of days it was more random. I have wiped the tv sensors with record cleaner and pledge and cloth on other occasions . 

So for now , it seems to be fine again ..