Symptoms
- Screen flashes black briefly then returns
- Picture cuts out for a second at random intervals
- Problem happens on all apps and sometimes on other inputs too
- Wiggling the HDMI cable changes the behavior
Likely causes
- CommonLoose or damaged HDMI cable or connectorA cable that isn't fully seated can cause intermittent signal loss.
- CommonHDMI-CEC or HDCP renegotiation happening repeatedlySome devices re-check copy protection periodically, causing a brief flash.
- PossibleCable not rated for the resolution/refresh rate being usedBandwidth-insufficient cables can drop signal intermittently at higher settings.
- PossibleFailing HDMI port on the TV or the streaming devicePhysical port wear can cause an unstable connection.
- Less commonOverheating device causing it to briefly reset video outputDevices tucked in tight spaces can behave erratically when hot.
What to do
- Unplug and firmly reseat the HDMI cable at both the TV and streaming device ends.
- Try a different HDMI cable, ideally one rated for high speed/4K.
- Test a different HDMI port on the TV to rule out a failing port.
- Lower the output resolution on the streaming device temporarily to see if the issue stops.
- Give the device more airflow if it's tucked behind the TV or in a cabinet.
- Turn off HDMI-CEC features temporarily to rule out renegotiation causing the flash.
- If the flashing happens on every input regardless of cable or device, the TV's HDMI board may need professional repair.
Tools and parts
High-speed HDMI cableSearch: “high speed HDMI cable 4K”
When to call a pro
If the flashing persists across all cables, ports, and devices, have a technician check the TV's HDMI board.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.