Locating Output Pin

[Teckno1]

I pull apart a Kidde PI2010 Smoke Alarm Dual Sensor smoke detector and was wondering if someone could help me find the output pin for the horn? I remove some of the wax from the board but cannot locate the output signal from the horn.

Thanks in advance.

 

[mgookin]

Why are you taking apart a radioactive device?

The control signal is via the red wire.

That "wax" is called a conformal coating.