Furuno FR-2155, Service Manual

Page: 43 / 152

2-29
2.28 Power Supply Circuit (AC)
AC PWR Board (03P9245)
The PWR board contains a main-inverter, a sub-inverter, and protectors. The main-inverter
pr24 V and +32 V (for scanner motor), while the sub-inverter produces –12 V, +12 V,
+32 V, and +140 V from +24 V, output of the main-inverter. +5 V is generated by chopping
+24V. Power fail (P.F.) signal generator outputs “High” signal normally and “Low” signal
when the main-inverter fails. The RP data is backed-up when the P.F. signal is received. +24 V is
adjusted by VR51.
Main-inverter:
With the POWER switch pressed, +12 V regulator, Q1 turns on, and over-voltage and low-
voltage protector, relay drive circuit, and switching regulator controller are powered up. The
protector U1 activates when ship’s main is lower than 85 VAC and higher than 135 to 150 VAC.
If ship’s mains is higher than 135 to 150 VAC, the relay in the input line, K1 is turned off by the
signal from the protector U1, and no power is supplied to the main-inverter. The switching
frequency is adjusted by VR1. A rush current protector Q1 and R2 prevents rush current from
being flow into smoothing capacitors C11 and C12. When the smoothing capacitors are charged
to the rated voltage, the main inverter starts oscillating. The output of the T1 turns on triac Q1
and the R2 10 ohms, 5 W is short-circuited. Ship’s mains 110 VAC or 220 VAC is jumper
selectable as show in the table below. Smoothing capacitors C11 and C12 are charged by 100 to
170 VDC respectively. +5 V is generated from 24 V by a chopper IC.
Ship’s Mains JP1 JP2 JP3 JP4 Fuse
110 VAC Connected Connected Connected Removed 10 A
220 VAC Removed Removed Removed Connected 5 A
Sub-inverter:
The sub-inverter produces –12 V, +12 V, +32 V, and +140 V from +24 V, output of the main-
inverter. These lines are not stabilized, but the +24 V line is stabilized by the main-inverter. The
switching frequency is adjusted by VR71.
Protector:
Over-current detector U91in the scanner motor power line (ANT MOTOR line) activates when
the current is 6 A or more for 0.8 seconds. The short circuit protector U72 operates when +140 V
line is short-circuited. The output from the U72 is latched by Q33 and then send to the switching
regulator controller U11.