Block Diagram Power; Dc Power Supply Circuit (03P9223); Main/Sub-Inverter; Protector - Furuno FR-1505 MARK-3 Series Service Manual

Block Diagram Power

DC Power Supply Circuit (03P9223)

The power supply circuit consists of a main-inverter, a sub-inverter, and a protectors. A P.F
(Power Failure) signal of "Low or 0V" is generated when the main-inverter cannot work
normally. This signal is sent to the RP-17 and all data is stored before shutdown.
Main-inverter
When the power switch is pressed, +12V regulator Q5 starts operating, and power is applied to
the input voltage detector and switching regulator control circuit.
The switching regulator is turned on with the input voltage of 21.6 V or more, and turned off
when the input voltage is 19 V or less. The main-inverter derives +/-12 V from the input voltage.
Sub-inverter
The sub-inverter derives +115 V for the CRT circuit from +/-12 V, output of main-inverter. +5 V
and +32 V for tuning control is generated by a regulator from +12 V.

Protector

The protector activates when the input voltage is lower than 19 V or higher than 43 V. The
protector in the power supply line for antenna motor trips when the current is 8 A or more for
more than 2.5 seconds. The TX-HV protector circuit is turned on when 8 A flows on the +12 V
line. The short circuit protector for +115 V is provided in the sub-inverter.
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