THEORY OF OPERATION MODEL MBC8 BATTERY CHARGER
(continued)
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 Charger.
MBC8(10003) iss2
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