My 12-year-old house security alarm 12V outputs are a siren and a strobe. I've just discovered that although the strobe itself is OK (12V starts it flashing) it isn't being activated. Hardly surprising as a quick check shows that the output connection marked 'Strobe +ve' goes to a low and rapidly varying value under 1V when the alarm is triggered, not 12V.
The company who made this 'Series 2000' unit (the 2250 model) is Autona Ltd, of Princes Risborough, Buckinghamshire, UK, but they seem to have disappeared. I'm assuming the strobe circuitry is faulty. So I've re-connected the strobe wire to the main alarm output instead. A test confirms it works.
Presumably the only effect of this is that instead of the strobe continuing indefinitely (as specified in the user instructions) it will time out with the siren? Respective consumptions for siren and strobe are 500 mA and 200 mA respectively, which doesn't seem like too much of an extra load for the siren circuitry.