Continuous alarm sound.

This problem usually occurs when trying to drive the Universal Alarm from a set of normally-open PBX dry-contacts. With just the power adaptor and the speaker connected to the Universal Alarm (and links J1 and J2 removed), one of the four selectable "exchange line #1 alarm-tones" is heard continuously.

The fault is usually caused by accidentally connecting a voltage across screw terminals 3 and 10 (i.e. the PBX contacts are not actually "dry"). This damages a component on the alarm's PCB causing the fault to appear. The only solution is to replace the Universal Alarm with a new one.