A PCB of sprinkler Annunciation Fire Alarm.

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Joined Apr 13, 2022
I have a pcb of sprinkler Annunciation Fire Alarm . it is operated on both ac220v /dc 24v.on this pcb 7812 regulator is used . to its common pin2 +24v is given and through a resistance and diode a bc 547 transistor is operated. problem is this i get at pin no. 3 24v dc instead of 12v. due to flash on pcb circuit tracks are burnt and value of resistance is not available. kindly suggest how it works20220413_191407.jpg20220412_191306.jpg20220412_184122.jpg20220413_191407.jpg20220412_191306.jpg20220412_184122.jpg20220412_184149.jpg20220412_191306.jpg
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