When I’m faced with an unfamiliar unit I “xray” the unit’s front panel with my pocket flashlight — inch by inch. I can usually spot the sensor because of a change in color. This does not always work. Sony will sometimes place the sensor in the logo’s “o” or Samsung will burry it in the power/operation button. The worst case is when I must systematically block areas with a business card or by relocating the emitter while giving commands.