BF BoardFaults
MODEL-SPECIFIC DIAGNOSTIC

Diagnostics / SMART / GX series

HDMI source reports no signal

The SMART Board GX is powered, but the selected HDMI input shows no signal from the connected device.

Applies to this documented familySBID-GX165, SBID-GX175, SBID-GX186

Likely causes, most useful checks first

  • Incorrect input selected.
  • Source device is asleep or outputting elsewhere.
  • Cable, adapter, wall plate or extender failure.
  • Input-specific hardware fault.

Safe checks

01

Confirm the exact input

Select the HDMI socket number that physically matches the connected cable.

What the result means: An image after input selection indicates a routing issue, not a panel repair.

02

Confirm the source output

Wake or restart the source and test it on another known-good display if available.

What the result means: Failure on another display points to the source or adapter.

03

Test a direct known-good cable

Bypass adapters, wall plates and extenders.

What the result means: A working direct path isolates the room cabling or accessory.

04

Compare another external input

Use a known-good source on another supported input without opening the display.

What the result means: One failed input with other inputs working should be escalated with the exact port recorded.

Sources

Reviewed under the BoardFaults safe-external-check policy · risk class: low · updated 2026-09-03