Power Supply Circuit (Ac) - Furuno FR-2115 Service Manual

Power Supply Circuit (AC)

AC PWR Board (03P9245)
The PWR board contains a main-inverter, a sub-inverter, and protectors. The main-inverter
produces +24 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
110 VAC
220 VAC
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.
Power for Scanner Motor:
Rectified +32 VDC is applied to the scanner motor through the ANT MOTOR line, MOTOR(+)
and MOTOR(-). The F/V (Frequency to Voltage) converter U93 receives bearing pulses (BP)
from the scanner unit and outputs DC signal depending on the frequency received. The
comparator Q94 compares the output of the F/V converter with the antenna speed data, 24 rpm
or 42 rpm. If the antenna speed is lower or higher than the rating, the comparator outputs the
signal to control the scanner motor supply voltage. Thus, the motor rotates stably. The VR91
adjusts the antenna rotation to 24 rpm (no adjuster for 42 rpm). The number of the antenna
rotation can be read on the self-test menu. The table below summarizes how to select the antenna
speed data.
Rotation
24 rpm Removed
42 rpm Removed
JP1
Connected Connected
Removed Removed
JP91 JP92
Removed
Connected
JP2 JP3
Connected
Removed
R98
4.7 k ohms Disregarding menu setting
1.2 k ohms Ant. revolution, Radar 3 menu; H
2-29
JP4
Removed 10 A
Connected 5 A
Menu selection
Fuse