If an HDMI input on the TCL QM8 shows no signal, check the source is on and the TV is on the right input from the input list. Reseat the cable at both ends, try another HDMI input and another cable, and turn the source off and on. Disable HDMI-CEC for a test if the screen goes black when devices wake. A console or streaming stick in sleep mode can show no signal until woken. If the picture works on another input, the first port may be damaged. For 4K HDR sources, use an Ultra High Speed cable and set the source to a lower resolution to find whether the cable is the limit. Unplug the TV for a minute and update it.
Differential
Likely causes of “TCL TV line shows no signal on HDMI”, and how to tell them apart
- 1
The wrong input selected
What separates it Blank screen with the source on
How to confirm Pick the correct HDMI input
- 2
A loose or poor cable
What separates it Signal flickers
How to confirm Reseat or replace the cable
- 3
CEC or sleep behavior
What separates it Black screen on wake
How to confirm Turn off CEC for a test
- 4
A resolution the cable cannot carry
What separates it Black screen at 4K HDR
How to confirm Lower the source resolution
- 5
A port fault
What separates it One input never works
How to confirm Contact TCL
Before you touch a setting
Record this first — changing settings destroys the evidence
- Input, source and cable
- Whether other inputs work
- The source's resolution setting
Try in this order
0 of 6 completedSelect the input
ReversibleUse the input button.
Reseat the cable
ReversibleBoth ends.
Try another input
ReversibleTest a different HDMI port.
Change the cable
ReversibleUse an Ultra High Speed cable.
Power cycle
ReversibleUnplug the TV and source for a minute.
Check the source's output
ReversibleMake sure the source's resolution and HDR settings suit the TV.
Model-specific
What is true of this model and not of its siblings
- Inputs
- Use the HDMI 2.1 inputs for the highest-bandwidth sources.
- Inputs
- Four HDMI inputs, two of them HDMI 2.1, according to one 2024 review.
- Other models this page answers
- These steps also fit models QM7, Q6, R655, R646, S555, S455.
Stop boundary
When this stops being a self-service repair
- !If multiple inputs fail with known-good cables, contact TCL
Evidence ledger
Sources behind this answer
Input, cable and reset steps.
Power cycle and remote tests.
HDMI issues.
General Google TV troubleshooting.
The company and its products.
Exact questions
Common questions
Why does my QM8 say no signal?+
The source may be asleep, the cable loose or the wrong input selected.
Does HDMI-CEC cause no signal?+
It can when devices wake each other. Turn it off for a test.
Which cable for 4K 120?+
A certified Ultra High Speed HDMI cable.
Can a bad HDMI port be repaired?+
TCL service can repair it, subject to warranty.
How do I find the HDMI 2.1 inputs?+
Check the labels or the manual.
Why does my game console show no signal on the QM8 only at 4K 120?+
The cable or input may not handle that bandwidth. Use an HDMI 2.1 input and an Ultra High Speed cable, or lower the console's output.
Does the QM8 need HDMI input settings for 4K?+
Some TVs need an enhanced or HDMI 2.1 mode for the highest bandwidth; check the input settings for a signal format option.
Why does my streaming stick show no signal after standby?+
The TV and stick may not wake together. Turn HDMI-CEC off, or restart the stick.
Can a surge or static cause no signal?+
A power glitch can upset the HDMI handshake. Unplugging the TV for a minute resets it.
Why is the picture black but the sound plays?+
An HDR or color format mismatch can cause it. Lower the source's resolution or switch HDR off for a test.