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I am using two PWM outputs from a Netduino 2 to control two servos. One of the PWM pins works perfectly fine but the other doesn't work until I have touched it with an oscope probe. The probe doesn't need to remain connected or even grounded. Just a small tap gets it running.

I removed the pin headers so I could directly solder the wires to the PCB so perhaps I damaged something? It's strange because everything works fine after I tap the connection with the probe. Both servos are powered and grounded from the same rails.

Any ideas/solutions?

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  • \$\begingroup\$ Could it be a cold joint? \$\endgroup\$ – venny Sep 18 '14 at 1:05
  • \$\begingroup\$ If you touch it with something non-conducting does it have the same effect? \$\endgroup\$ – copper.hat Sep 18 '14 at 2:04
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    \$\begingroup\$ Could it be configured as an open-drain output and you need a pullup to make it work reliably? \$\endgroup\$ – John D Sep 18 '14 at 4:50
  • \$\begingroup\$ I just switched to another PWM port. I don't think it was a cold joint, the joint looked pretty solid and I re soldered it twice to make sure. \$\endgroup\$ – user3588119 Sep 18 '14 at 5:08
  • \$\begingroup\$ Can you show a circuit diagram and photo of what you built? \$\endgroup\$ – jippie Sep 18 '14 at 5:54

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