Furuno FELCOM 12 Service Manual

6-6
Send Level NG
Send level is calculated based on the current on the power supply line to the antenna unit.
The current detector R51 locates at the output of the rectifier on the SW REG board. The
signal detected by R51 is sent to U8, Q55 and Q51, and output to the CPU board as ANT
CUR signal. On the CPU board, the ANT CUR signal is A/D-converted by U71 and
delivered to CPU2 U23.
Transmission sequences:
The HPA ON signal generated by CPU2 U23 is sent to the PIO U13 and then the voltage
controller Q52/U10 through U54 and U57 on the SW REG board. The voltage controller
selects +29V for transmission, resulting that the current on Q51 increases and Q56 goes
on to turn on the fun. The send level is more than 123, normally the maximum 255. If the
level is less than 123, TX circuit in the antenna unit or the SW REG board may be
defective.
CPU2
(U23)
PIO
(U13)
Power trans
(T1)
U8
•F
RC9083
Voltage control
(Q52/U10)
Q55
5V
Q51
Q57 Q54
+ 18V (RX)
or + 29V (TX)
ANT CUR
CPU
(16P0148)
SW REG
(16P0149)
J4-8
J4-7
J3-1
HPA ON
ANT VOLJ4-6
Q56
Rectifier
R51
(0.05
Ħ
)
R52
IN
FANJ5-2
12V
J5-2
FAN
ANT CUR
ANT VOL
A/D
(U71)
AGC LEV
TX LEV
J9-7
J9-8
J9-6
HPA ON
Antenna unit
R61
R62
J4-5

Furuno FELCOM 12 Specifications

General

Brand	Furuno
Model	FELCOM 12
Category	Marine GPS System
Language	English