How do I wire my lj18A3-8-Z/BX to my prusa? going insane
May 04, 2016 04:19AM
Hello, I am having troubles wiring and installing a LJ12A3-4-Z/BX sensor. I found several tutorials but I do have some questions and confusions.
1. I found three tutorials. One saying you need one 10k and 15k resistances, another 15k and 20k and one that says if I put 5 volts as a source I don't even need to put resistances. Which one to follow?
2. Where to put the wires? In one of the tutorials, I saw a person cut the standard z-sensor and wire up the z sensor slot and its connector :| Others take 2 specific of the soldered wires, hook them up to 12v and the third into the one of the 3 holes in the z-stop.

My final stance is to cut the 3 wires of the Z endstop and solder brown/brown blue/blue black/black. I found that the zendstop provides 5 volts and althtough the 6-36v source is more than 5, people say it still works nicely. Its also less to solder and no waste of electricity. I still am not sure its ok to do this. Reaching out for a pro. I am also requesting some pictures of your soldering and setup if you have such a setup.

My board is "mks gen-2z v1.2" and the sensor is LJ12A3-4-Z/BX, with the yellow knob.
I have a glass + aluminium bed and the upgraded hotend, everything else is stock.
Re: How do I wire my lj18A3-8-Z/BX to my prusa? going insane
May 10, 2016 05:17PM
On a glass, you need a sensor type LJC12A3-4-Z / BX
the sensor LJ12A3-4-Z / BX detects only the metal.

1) After everything depends if your sensor is an NPN or PNP.
With a PNP sensor, it is mandatory the resistors to a voltage divider.
With NPN sensor, no need for resistors, you can connect it directly.
I have a LJC18A3 H Z / BX I connected like this:
- Brown on the 12V
- Blue on the ground
- Black on signal

2) If the sensor is NO. In the firmware to: const bool Z_MIN_ENDSTOP_INVERTING = true
If the sensor is NC. In firmware to: const bool Z_MIN_ENDSTOP_INVERTING = false
AH, an other useless auto bed leveling probe saga . smiling smiley
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