Added a doorbell push button to newly installed Chamberlain garage door opener...linked push button wires to same contacts as the incoming control pad inputs (red and white). Doesn't work. Is this wired incorrect?
A regular push button either normally closed or open will not work on most modern garage door openers, because the control pad doesn't just short or open the wires. They use resistors or some other mechanism to vary the voltage going back to the motor controller.
You must purchase a Chamberlain compatible push button.
RE: LW3500 unit.
I like the wiring across the switch solution (above) in many cases, but I did not want to run wire over to the main switch. So, having another unit that I have not yet installed I did a little research.
Across the two input connectors are:
1 A 1500 ohm resistor in series with a green LED. Power light.
2 The primary switch with nothing else. In other words a dead short when pressed.
3 The Lock switch is wired in series with a 22uf cap. Long pulse when pressed.
4 The Light switch is wired in series with a 1uf cap. Short pulse when pressed.
CAUTION: these Caps are polarity sensitive, but if the LED lights, you wired it correctly.