Meeting room TV says No Signal — the fix both LG and Samsung document

What this error means

The industry calls it an HDMI handshake failure; the manufacturers just document the cure: power off the TV AND the source device, physically disconnect the HDMI cable at BOTH ends, reconnect firmly, and cold-boot (Samsung's version: unplug the TV itself for 30 seconds). Their other documented steps: verify the right input, try a different HDMI port, try a different (certified) cable, and update the TV firmware — Samsung even builds in an HDMI Cable Test on many models.

Symptoms

• 'No Signal' on the correct input
• Worked last meeting
• Picture but no sound, or intermittent black flashes (same family of fault)

Try this first (safe DIY steps)

1. Power off TV and source; unplug HDMI at BOTH ends; wait 10 seconds; reconnect firmly
2. Still dead: unplug the TV from wall power 30 seconds (cold boot), retry
3. Try the next HDMI port, then a known-good cable
4. Samsung models: run Settings → Support → Device Care → HDMI Cable Test
5. Check for TV firmware updates — HDMI quirks are patched constantly

Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.

When to call a technician

A port that never works with known-good everything = board-level TV repair; on consumer sets used as room displays, compare against replacement.