BL Touch Wiring Harness Fault - Blows V2 Board



  • I have just got a real BlTouch from Creality, BUT, as soon as I plugged it into my board (carefully following the installation instructions), I could smell smoke, and the V2 board died.
    I am an electronics engineer and managed to fault find the board and discovered that the SMD fuse "F2" on the output of the 5V regulator on my V2 board was blown (it had turned to black charcoal). Fortunately, I was able to replace the fuse with a PTC resettable fuse, and this bought the board back to life.

    The fault was caused by a wiring harness error in the supplied Creality harness.
    After I had cut the harness wires (I had fitted the harness inside the cable mesh, so did not want to undo that), I noted that the 5 way connector on the BL Touch had swapped RED and BLUE wires. (they are correct on the "servo" connector). The result of this fault is that as soon as the BL Touch Is plugged in, it short circuits the 5V supply. The fuse then blows, and the board dies- nothing appears on the LCD and the machine is dead.
    If you get a BL Touch I would strongly recommend checking the wiring BEFORE turning the Ender ON to avoid this problem.

    I have seen other posts where "the board died after fitting a BL Touch" and I wonder if this faulty wiring harness is perhaps common?

    ![alt text](Screenshot 2021-05-12 120349.jpg image url)

    I have had clone BL Touches before, but thought I would get a "real " one this time, so I was very disappointed by the Creality or Antlabs failure of quality control.



  • Thanks for comments guys.
    I have updated firmware with "proper" marlin and configured using Platformio.

    Now working and about to add filament sensor,

    PS I used a standard wire ended 1A nominal PTC and soldered it to the nearby capacitors. See photo..
    I also found I was not the only one to have been caught!!>
    see this post..!
    Screenshot 2021-05-13 190826.jpg



  • @dagnall crappy deal indeed.

    Doesn't help you now, but side note/info to others: if you need to swap wire order, you can also release and pull the individual affected wires out of these connectors, and stick them back in the correct spot.



  • @dagnall Sorry to hear this.

    The BLTouch kit you purchased with that cable does indeed have the cables inverted and is a known issue with Creality 4.2.x boards. When I purchased my BLTouch I made sure I got the one with the dedicated cable for the Ender 3 V2 that plugs into the dedicated BLTouch port only (the cable only has one plug at each end) and not the one you have that uses the Z axis port.

    Glad you got it working though. Remember to use the right firmware to activate it and also to make sure the Z axis is not close to the bed at power on or the probe will error out or could be damaged while homing (I did this by mistake once).

    BLTouch Cable

    John


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