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

TomTom Go 910 Repair

The following describes the repair of a TomTom Go 910 which had been overvoltaged (connected directly to 12V).

https://docs.google.com/file/d/0B43XXiSt0MIdcnJyQVJHQVM1YlE/edit?usp=sharing

The root cause of the failure was a break in the feedback conductor in the GPS power cable, which had caused the input voltage to rise above the absolute maximum of 6V, destroying 3 power supply components.

The design of the car power supply is poor in that a simple break in one of the cable conductors can cause a damaging voltage to be applied to the GPS.

The components have been replaced, and the GPS tested with a clean 5V supply.

The power supply was later repaired by shorting the red and white conductors at the power supply end of the cable.

Burned out components in TomTom Go 910