BlTouch Probe Trouble

I have recently bought a BlTouch Probe and tried installing it on my DIY Printer with a Smoothieboard v1.0a
After following the available guide i could extend the pin and probe the printer bed. But after retracting the pin, it wont stay up and keeps falling down and immediately retracting in irregular intervals. Also, when i extend the pin of the probe, the led on the third big mosfet, controlled by same pin 1.23 as the BlTouch Servo, is lighting up and wont go out even after retracting the pin.
Video (htt p s://youtu . be/vGfeLOe1YYA) of the pin going up and down.
Thanks for any help solving this problem

Imported from wikidot

How long is the cable from your Smoothieboard to your bltouch ?

Bltouch is a flawed concept in that it uses PWM over long cables, and for some users, noise will make that unworkable. Very possible that’s what’s going on for you, if so switching to shielded cable and twisted pairs may help. If not, your only chance is switching to differential signaling, which is a lot of work.

Thanks for the answer.
My cable is an about 1,5m long Cat5 Shielded Network Cable. So shielding shouldn’t be the problem, but maybe the length is.
Could the LED on the Mosfet lighting up be in any way related to the problem?

1.5m is very very long for a 3.3v PWM signal … most bltouch users have prusa-i3-sized printers where this is much less of a problem.

I don’t expect the mosfet to mean much.

I recently had he same problem. But for me the BL-Touch was OK until the extruder was hot. When the PWM of the extruder was keeping it at the constant temperature the BL-Touch was going up and down randomly.

The fix was to separate the wires from the extruder heater. I used thick wires for the extruder heater, and tried to put some distance to the wires of the BL-Touch. This solved my problem.

In your case, maybe use shielded wires for the BL-Touch