That flickering TV light..... - Page 1
Forum section: electronics / general

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 20, 2022, 05:11:42 pm
content: This question is on behalf of an acquaintance, who has observed a peculiar event on his TV. Its a Toshiba flatscreen. I don't know whether its a smart TV or not, but he seemed uncertain of what I was talking about when I asked him, so I simply asked him whether it was connected to the Internet and he said no. He just uses it as a TV.The TV has a light that flickers when he turns it On and also when he turns it Off, presumably indicating some activity on startup and shutdown. What he has also observed is that every 3.00am, without any intervention the light comes on and flickers for around half an hour before turning off again. He was asking me what is happening when it does that?The only thing that springs to my mind is some form of OTA update, but why would it do it 30 mins every night?I didn't have time to properly examin the setup, but he lives in accommodation designed for elderly people. I don't think there is any antenna on the roof for reception and in any case they have Virgin media, so its possible the TV is connected to some kind of VM cable receiver.Does anyone know what the TV might be doing, and can it/should it be turned off?

author: james_s
author_rank: Super Contributor
timestamp: October 20, 2022, 05:27:48 pm
content: Is there any mention of it in the owners manual? My guess is it's some kind of software update, or information harvesting. Is it connected to his wifi or ethernet network? Maybe check that for traffic.

author: AndyC_772
author_rank: Super Contributor
timestamp: October 20, 2022, 05:39:31 pm
content: It's possible that it's testing and compensating for the natural degradation of the panel over time.I know my LG OLED TV does this, though the process is far less frequent - I maybe notice an unexpected flash of the screen every couple of months or so. It does a longer panel refresh overnight even less often, so I'm told.If that's the case then it's totally normal, not sinister at all, and just done to keep the perceived image quality as consistent as possible for as long as possible.

author: tom66
author_rank: Super Contributor
timestamp: October 20, 2022, 05:56:18 pm
content: My Panasonic plasma TV used to do this, it was indeed searching for OTA updates. These were done over a certain Freeview channel and Panasonic's slot was at 1.30 am if I recall correctly, and it was around half an hour as well. It used to sit in our bedroom and the relay click on would sometimes wake me up, the power light would blink green rapidly while the board 'booted' then the LED would turn off. The really annoying thing was it would pull 20 watts sitting there with all the power electronics running but screen off, only to not download an update as they weren't released after a few years of that model's life cycle. It seemed a bit bonkers to me.

author: Bud
author_rank: Super Contributor
timestamp: October 20, 2022, 06:07:37 pm
content: You guys could check if you can turn off automatic updates in the TV setup menu.

author: themadhippy
author_rank: Super Contributor
timestamp: October 20, 2022, 06:15:00 pm
content: simple solution,unplug ,or turn off the socket when the tellys not in use,added advantage you'll save a few pennys compared to leaving it in standby

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 20, 2022, 06:35:01 pm
content: Quote from: tom66 on October 20, 2022, 05:56:18 pmIt would sit there for 30 minutes even thought there was no update to download? That would be consistent with what is happening here, but why would it sit for so long? Ok, thinking about it, its OTA right, so the whole thing would be transmitted periodically and the telly would have to sit a while waiting for the transmission to start. I am not sure how long the transmission takes or how often or how many times they were broadcast during the given time window, but I guess it would not be unreasonable for it to have a timeout of a few minutes.Next time I see him, I will ask him whether he has a manual and I can get more details and check whether it can be turned off.Quote from: AndyC_772 on October 20, 2022, 05:39:31 pmInteresting. I was not aware of such a process. This set is a little older and not likely to be an OLED. Most likely an LED display so am curious as to whether it would apply?

author: tom66
author_rank: Super Contributor
timestamp: October 20, 2022, 09:35:30 pm
content: Quote from: WaveyDipole on October 20, 2022, 06:35:01 pmMy understanding was when I worked at a certain set-top box manufacturer was every one of the manufacturers who worked/licenced Freeview tech/branding would get an allocated slot on a channel for an update but this was for all of their models.So perhaps the 30 minutes was there because it had to download the full update only to figure out it's not any good. But it does seem a bit stupid to me.It would have probably been over a data channel over MHEG (not MPEG) so the data rate is not spectacular, probably a few hundred kbit/s at best.

author: eti
author_rank: Super Contributor
timestamp: October 20, 2022, 11:31:28 pm
content: A strip of insulating tape over the LED = problem solved!

author: Ranayna
author_rank: Super Contributor
timestamp: October 21, 2022, 04:35:54 pm
content: Our now 18 year old Metz with satellite tuner does that during the night (or did, i'm rarely awake at that time anymore) to update the EPG with info that is, or was, broadcast on a special channel.Well, it does not flicker, but when it's in standby, with it's red LED, the LED turns greens, as if it was turned on. Stays green for a couple of minutes, then goes red again.But the EPG is broken for quite some time now (we don't use it anyway), so they might have stopped broadcasting the data, at least in a format compatible with the TV.This TV is way older than current "smart" technology, it's not even Full HD yet.

author: james_s
author_rank: Super Contributor
timestamp: October 21, 2022, 05:22:01 pm
content: Quote from: Ranayna on October 21, 2022, 04:35:54 pmI worked at a company that made settop boxes for a while and I am fairly certain that what happened to your TV is what happened to our earlier boxes as well. At some point they were old enough that the company decided to stop supporting them and simply shut off the servers that had been providing the data. This is why I like everything standalone with no dependency to external systems for basic operation.

author: WaveyDipole
author_rank: Frequent Contributor
timestamp: October 27, 2022, 05:43:07 pm
content: Thank you for all your feedback. I have passed all that on to my acquaintance and he was grateful for the information.

author: Twoflower
author_rank: Frequent Contributor
timestamp: October 27, 2022, 06:55:10 pm
content: Quote from: themadhippy on October 20, 2022, 06:15:00 pmThe problem with that is, at least for OLED displays: They do a kind of wear leveling when not in use. If you don't allow that the screen will show artifacts reasonably soon. You should check the manual to see if they warn you not to unplug the telly.