Is my SN04-N defective?

Hello.
My first 3d printer arrived.
Just assembled Tevo Tarantula and I manually leveled the bed and was trying to get the proximity sensor working. I plugged the SN04-N sensor where I had my Z-stop trigger.
The led on the sensor is always on. Tried to get it close or far from metal parts. Have flashed to Marlin and it's still on. Is the sensor defective, badly wired or needs settings in Marlin?

SN04-N: DC 10-30V, NPN NO, Three wire

The brown wire will need to go to 12v
Blue = 0v
Black = signal

The connector feeds the brown wire with only 4.85 V.
I tried to connect only brown and blue to 12V and the light is still always on.

Well the light should only be on when the probe is close to a metal trigger, so definitely seems like it is faulty.

The same thing happened to me.
Watch Video

[youtu.be]

Note that light light actually changes when metal is placed in both cases, light gets brighter in the second socket.
And set all to =true for HIC i3, was all =false
Plug into X_Min

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
#define X_MIN_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING false // set to true for SN-04N False for TL-W3M.
#define X_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING false // set to same logic as "Z_MIN_ENDSTOP_INVERTING".


If light get brighter when metal is in close proximity then you need to check both programming and wiring.
Mine was both - the Video is programming

I ordered 5 new sensors, and all of them work as expected. How unlucky was I with the first one.

No,
Today it happen to me! I turned on my printer and saw that the sensor's LED is on.
There might be an issue with the wire. In my case the black wire was broken and most probably your too!