Demonstrating one of the perils of being right on the coast, this is the PC board from the outdoor sounder box of an alarm system which has been up for about 6 to 7 years.

It doesn't look too bad from the front:

[Linked Image]

But looking at the back shows how once the protective screen starts to deteriorate at the edges, the board soon starts to suffer from the weather:

[Linked Image]

The strobe light had stopped working completely, and the alarm had started to sound randomly, sometimes just a "chirp," sometimes a blast of two or three seconds.