Dettol Soap Dispenser Repair

The following describes the "repair" of a Dettol no-touch soap dispenser, which was producing too much soap then flashing the red light.

https://docs.google.com/file/d/0B43XXiSt0MIdTFZGS0hqc3J6QWs/edit?usp=sharing

The root cause is that the design is not tolerant to the high voltage provided by good quality fresh batteries.  A diode was inserted in the circuit to ensure it works with fresh batteries.

Disassembled Dettol Soap Dispenser showing PCB