Welcome to Just Answer, my name is XXXXX XXXXX would be glad to assist.
First, look in the panel for a Master Relay, as many of the low voltage panels had a Master that would disable power to each of the relay circuits.
Follow the wires from the transformers and find the first location that the wire is connected .
Is the transformer labeled? Wanting to be sure the 12 volt is supposed to be 12 and not 24 volts as well.
What relays are in the panel? RR-8,RR-9,RR-7?
Post what information you find.
There is no Master Relay that I could see.
Transformers are correct with proper voltage outputs (one 24VAC; one 12VAC). One leg of the 24VAC transformer foes to a rectifier; the other into the main panel where it connects to 4 or 5 other wires. The transformers have some writing on them which is hard to read without removing - don't want to do that, especially since there's nothing wrong with them. My neighbor has the identical system so I can compare - mine looks the same and has same voltage readings - 24 and 12 VAC.
Cannot tell what Model the relays are - impossible to read them the way they're installed in the panel. I don't want to remove them - relays were all working one minute, then all 12 stopped working all at once.
Cannot fathom what went wrong.