Compatibility & scope
Based on Hisense's English e-manual whose PDF metadata title is E-Manual MT9603 VIDAA U9 NA/SA (the manual prints no date or version; the PDF was created in 2025), downloaded from Hisense Chile (hisense.cl), where it is hosted for the 58Q6QV, 40Q4SV and 50A4NV. These are model codes from Hisense Chile's site; equivalent models elsewhere and other TV brands that run VIDAA may differ. The manual says Auto Sleep and Auto Standby with No Signal may not apply to some models, countries or regions. It does not list the timer durations you can choose or the factory defaults, and it does not describe any overheating shutdown. Documentation reviewed; no TV hardware tested.
In this guide
Usually a timer, a lost signal or a connected device
When a VIDAA TV that matches Hisense’s 2025 U9 e-manual switches itself off, the manual points to four causes: the power supply, one of the TV’s timers, the Auto Standby with No Signal setting, or CEC Control putting the TV into standby when a connected HDMI device turns off. All the timers are in one place: press Home and open Settings → System → Timers.
If the TV restarted on its own just after you ran Remove User Data or Reset to Factory Default, that’s expected: Hisense says the TV restarts itself during those operations.
Match what you saw to the likely cause
| What happened | Most likely setting | Where to check |
|---|---|---|
| The TV went off at a particular time | Sleep Timer or Power Off Timer | Settings → System → Timers |
| The TV went off while you were watching but not touching the remote | Auto Sleep | Settings → System → Timers |
| The TV went off while showing an input with no signal (for example, a games console or set-top box that was off) | Auto Standby with No Signal | Settings → System → Timers |
| The TV went off when you switched off a soundbar, set-top box or other HDMI device | CEC Control | Settings → Connection → HDMI & CEC |
| The TV went completely dead, not into standby | Power cord or wall socket | The back of the TV |
Check the timers
- Press Home on the remote and open Settings (the gear icon).
- Open System → Timers.
- Look at each of these and switch off any you don’t want, or set a longer time:
- Sleep Timer turns the TV off at the time you set.
- Power Off Timer turns the TV off at a set time.
- Auto Sleep turns the TV off after a period with no activity, of the length you choose.
- Auto Standby with No Signal puts the TV into standby when the current input has had no signal for the set time and you haven’t used the TV.
The manual doesn’t list the time options or say which timers are on by default, so check each one rather than assuming. Auto Sleep and Auto Standby with No Signal aren’t on every model. Hisense presents these timers as energy-saving features, so switching them off may increase power use.
If the TV turns off with your soundbar or set-top box
With CEC Control on, the TV goes into standby when the HDMI-CEC devices connected to it are turned off, if those devices support it. That’s useful if you want everything to switch off together, but it can look like a fault.
To stop it, press Home and open Settings → Connection → HDMI & CEC → CEC Control, and set it to Off. With it off, you also lose the CEC link that lets the TV remote control the connected device. Device Auto Power Off on the same screen works the other way round: it turns the connected devices off when you turn the TV off, so it isn’t what’s switching your TV off.
If the TV loses power completely
Check the power cord is firmly plugged into the TV and the wall socket. Hisense notes that the TV shuts down if it’s disconnected. If the cord is fine, restart the TV: turn it off, unplug it, wait 60 seconds, plug it back in and turn it on. A restart doesn’t clear your settings.
If the TV keeps switching off after you’ve checked the timers, CEC Control and the power cord, note the TV model and when it happens, and contact Hisense support for your country.
Common questions
My TV turns itself on. Is that a timer too?
It can be. Check Power On Timer in Settings → System → Timers. Also check TV Auto Power On under Settings → Connection → HDMI & CEC: it switches the TV on when a connected HDMI-CEC device is turned on.
Does the TV turn off when it gets hot?
The manual doesn’t describe a heat shutdown. It says the TV getting warm during use is normal and recommends a well-ventilated position.
Sources & scope
Pages printed 35, 39–40, 64, 90–91, 101–103 (PDF 36, 40–41, 65, 91–92, 102–104)
View sourcePDF page = printed page + 1. Consulted: Use Timers (energy saving), Use HDMI & CEC (CEC Control, TV Auto Power On), Use Timer (Settings > System > Timers list), Restart your TV, and the Troubleshooting entries 'The TV automatically turns on or off by itself' and 'The TV is hot'. Home button icons checked on rendered PDF 36, 41 and 102. The same text is in the hisense.cl e-manuals hosted as User-Manual-40Q4SV.pdf (PDF 35, 39–40, 63, 90, 99–101) and User-Manual-50A4NV.pdf (PDF 38, 42–43, 66, 93, 102–104). The manual's front matter lists no models, date or VIDAA version: model names come from the hosted file names, and VIDAA U9 NA/SA and 2025 from the PDF metadata title and creation date (May 2025; uploaded to hisense.cl in November 2025).
These instructions are based on manufacturer documentation. They have not been device-tested for this guide.
Based on Hisense's English e-manual whose PDF metadata title is E-Manual MT9603 VIDAA U9 NA/SA (the manual prints no date or version; the PDF was created in 2025), downloaded from Hisense Chile (hisense.cl), where it is hosted for the 58Q6QV, 40Q4SV and 50A4NV. These are model codes from Hisense Chile's site; equivalent models elsewhere and other TV brands that run VIDAA may differ. The manual says Auto Sleep and Auto Standby with No Signal may not apply to some models, countries or regions. It does not list the timer durations you can choose or the factory defaults, and it does not describe any overheating shutdown. Documentation reviewed; no TV hardware tested.