Furuno FAR-2107 Series Service Manual page 411

3. Turning the power ON
The status of power switch of RCU-014 and RCU-015 is detected at the window
comparator comprised of U3 and U4. The power switch is of a latch type and
opens when the power is ON and closes when the power is OFF. U4 output
switches +12 VDC power supply at Q3 via U2 and Q4 and generate "PR12_A".
This power is supplied to the +32 VDC switching power supply circuit and the
+24VDC, +12 VDC and –14 VDC switching power supply circuits.
4. Tuning AC input circuit on by PWR ON1 signal
When the PR12_A power supply is turned on, U12 is turned on and PWR ON-1
signals control the triac and K1 control circuit.
First K1 is turned on, AC current runs through R40/124. Next the triac is turned on
and AC input power supply is connected to the rectifier circuit CR26. This circuit
is intended to reduce rush current. The rectifier circuit operates as a voltage
doubler rectifier circuit by the setting of J108 when 100 VAC is inputted
5. Turning on the switching power supply by PWR ON2 signal
PWR ON-2 signals from the triac and K1 control circuit drive two "DT Cont., Soft
start" circuits of Q41/42 and Q43/44 via U13, Q16, Q17 and control the HIC for
controlling the switching power supply of U21 and U22. The HIC incorporates
MB3759 for controlling the switching power supply of a pulse length modulation
type.
Control of antenna DC motor power supply
The antenna revolving speed differs according to the models of antenna motrs and
power boards. In case of the power board of 42 rpm type, the antenna revolving speed
can be changed by the setting according to 03Pxxxxx-B and 03Pxxxxx-D types.
ANT ON
BP
ANT SPEED
BP
SPU-013
Fig. 7.3.25 Schematic diagram of antenna DC motor power supply
ANT
Control
(Speed, ON/OFF)
RPU-013
ANT Motor
+24VDC 42rpm
J610
+20VDC 36rpm
REG
(ANT Motor)
[SCANNER]
PWR
7-67
7.3 Processor Unit: RPU-013