Ok, so I may understand: the voltage divider composed of R34 R35 & R36 bias the V12 zener at a certain voltage, then bias the base of the NPN V11, it shorts to ground the PNP V9 that activates the relay. And I guess that, as the relay controls the center taps of both transformers, it doubles the output transformer voltage when the voltage divider reach the V12 bias voltage. Maybe to lower the voltage drop in the power transistors ?
Am I correct ?