How do I stop my TV from going into sleep mode when connected to Mac mini M4 with HDMI cable?

What make and model is the TV..?

Does it happen when the Mac mini is active and sending video to the TV or when the Mac mini is idle for 10 minutes..?

At this point, it's hard to say if it is the Mac mini or the TV is causing the problem.

Somethings to check and try on the Mac mini side:

1) Set the "Turn display off when inactive" timer to a longer period of time in the Lock Screen Setting.

2) Turn on "Prevent automatically sleeping when the display is off" in the Energy Settings.

Something to check on the TV side:

1) Go to the TV's menu and check the Standby, Power, Eco or Energy Saver settings.

meddle wrote:

Thanks for your reply.

The TV is a TCL - 55" Class F35-Series 4K UHD HDR LED Smart Fire TV (2025)

This happens when the Mini is active. I’ll be typing away or browsing the net and every 10 minutes the TV screen goes dark until I press a button on the remote to wake it back up.

I will check out the settings you mentioned.

You're welcome.

Yea' that's sounding more like a TV setting than an Mac mini setting.

Below is from a simple Google Search

If your TCL 55" F35 TV keeps falling asleep, it's likely due to an active sleep timer or power-saving setting. To fix this, you need to disable the sleep timer and power-saving modes in the TV's settings. 

Here's how to do it:

1. 1. Access the TV's settings menu.
2. Use the remote to navigate to the settings menu, typically found by pressing the "Settings" button on the remote or accessing it through the main menu. 
3. 2. Find the "Power Saving" or "Eco Mode" settings.
4. Look for options related to power consumption or energy saving. Disabling these modes will prevent the TV from automatically turning off due to inactivity. 
5. 3. Disable the sleep timer.
6. Locate the sleep timer setting (often found under "System" or "General" settings) and disable it. 
7. 4. Check for other connected devices.
8. If the TV still shuts down automatically, it might be due to a device connected via HDMI that's controlling the TV's power. Disable the "Control Other Devices" or "CEC" option in the settings menu to prevent this. 
9. 5. Ensure a stable power source.
10. Make sure the TV is securely plugged into a working wall outlet and that any power strips or surge protectors are functioning correctly.