Leaderboard

I would think the panel is still "in alarm". Perhaps it needs to be reset, possibly engineer reset (different code) It is common for the sounder to silence but for the strobe to continue to activate - this was to indicate where the alarm activation was. It is unlikely that the bell/sounder/strobe assembly has just developed a fault - credit to you for disconnecting wires and measuring voltages etc but you might be heading towards the "somethings gone wrong" route when in fact the answer is most likely more simple.

Replacing transformers wouldn't be general practice at all, you would replace the whole control panel. It's all down to competence with being able to connect and isolate the electrical/electronics if your DIYing.