A board consisting of a Zmin Pin with built-in large capacity Capacitor.

(Melzi, Ender-3, ANET, etc.)

Since 2015, we have announced that Zmin Pin which one has a  large capacity capacitor on Melzi compatible board can make an issue. Most board manufacturers are aware of this, and generally, produce boards by removing capacitors from the Endstop(X-, X+, Y-, Y+, Z-,Z+) input or reducing them to a smaller capacity.


However, some boards still produce large capacitors, which negatively affects sensor operation. Of course around 0.1㎌(100㎋) is not a problem. BLTouch does not operate normally with a large capacitor in the Z-Stop. And we do not guarantee its normal operation. It just seemed to work well.

If noise, etc. interference is expected, you should use a anti-interference extension cable(Shielded or Twisted  Cable or Copper Shield Network etc.).

In principle, capacitors should not be attached to signals(e.g., interrupt, end-stop, emergency switch, data bus) that do not tolerate delay times, as opposed to intended signals(e.g., a temperature sensor).


Removing misplaced capacitors from the beginning is the only and complete solution.

For the use of BLTouch with a board with a large capacity capacitor in Endstop, you must choose one of the following two solutions:

1. Remove the capacitor(recommended)

          Even if Smart V3.0 produced since April 5th, 2019, we still recommend removing capacitors.

It is a safe and complete solution.  Removing it does not cause any problems in your system. 

Moreover, also any future use of any sensor will provide better precision. 

It works well in Logic voltage Free mode (default : open drain).

ex)   Step 1 : Turn off the power of the 3D printer.           

        Step 2 : Remove the capacitor : C7(Melzi/Ender-3) / C45(Anet)​            

        Step 3 : Clean the debris on the board.

2. Install around 1KΩ resistance(pull-up) between +5V(Red) and Zmin(White). ← only Smart V3.0 produced by April 4th, 2019.

However, this method provides poor precision because of the capacitor. This is because when triggered, the control board can be recognized as a position value that differs from the actual position. 

A smaller resistance may be necessary to reduce the delay time. It may damage your control board.

This issue has been and will continue to be in the previous version. That's because it can't be solved without removing the capacitor.


          You can track production dates with unique QR codes marked on BLTouch. Please click here.


If you want more precision bed leveling, please choose number 1.