Identifying a zener diode

CN204 isn't shown on the circuit section I posted, but Q211 is just a switch, with the input on the emitter, and the output on the collector. As R274 is powered from this switched 9V rail, then the Q212 regulator is switched as well.

You already know that you can't have the different voltages on the same piece of track - is one perhaps on mains, and the other on battery?.

<You already know that you can't have the different voltages on the same piece of track - is one perhaps on mains, and the other on battery?.>

I don't see how--both tracks intersect with the fused + output track from the bridge rectifier. I'm measuring 11.9v at this point. My thinking has been, since the output of the rectifier goes directly to Q211 I should have 9v here (and battery is 9v), so if I measure 12, the problem is rectifier or pre-rectifier. On the other hand, since the output of the rectifier also goes directly to a connector labeled 12v, and that's what I have, the rectifier is OK. That's why I'm confused.

That's also why I'd hoped the white dots on the tracks might give me some clue: They are on the tracks to and from the transformer primary and secondaries, and they are on the bridge rectifier output, battery input, and a 3v track?

Thanks again.