THEORY OF OPERATION MODEL MBC8 BATTERY CHARGER
CRANK DISCONNECT The crank disconnect relay is supplied by the DK terminals. This reed relay shunts the SCR
pulse transformer input when operated which prevents SCR turn on.
SHUTDOWN The shutdown sense line (SD) is connected to the internal SCR trigger drive signal on the regulator board
through a diode. The SD line does not input current and will not discharge the battery on power outage. Thus with a
shorted output, the load will "Steal" the SCR trigger drive signal (via terminal +B), preventing SCR turn on, to shutdown the
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