Activating HKC Sounder on Bench

[Eugene's DIY Den]

I've taken my sounder off the wall and I'm checking it on my workbench. It's powered from a desk power supply set to 12 V, connected to the external bell input terminals. I would have thought it would activate with the back tamper open, but it didn't. I closed the back tamper for 4 seconds and opened it and it still didn't activate and tried the same with the battery connected. Shouldn't all of these tamper conditions and also open circuit holds activate the unit? If a burglar cuts the cable, shouldn't the 6 V battery activate it, or is it only edge triggered (i.e when the tampers were initially closed when the sounder was powered down and then opened that triggers it? ) In this case, how can I generate a false alarm? Which terminals do I need to connect?

Edited 12 hours ago by Eugene's DIY Den

[Eugene's DIY Den]

I'm thinking I need to connect 0V from the power supply to SAB Hold, because that's actually the negative power supply to the sounder. Then connect 0 V to to External Bell -, because that seems to be Trig - on the schematic.