Bose SoundDock 10 Service Manual page 66

SoundDock 10 Theory of Operation
Microcontroller supply voltage
+3.3V supply for PIC micro-controller
Always on
+24V reduced to below 7V in low power mode
iPod Charging
+5V_DKSW is the iPod charging voltage
ZR400, R431-432 and Q406-407 are the over voltage protection for iPhone
compatibility
8