Furuno FS-1570, Service Manual

Page: 132 / 322

5.3 T-CPU board (05P0732)
5-15
Table 5.3.4 Signals generated by DATA 1 on TX/RX board
(Cont’d)
TX/
RX
Pin No.
& Name
Order of
execution
Signal name Function
#15 QA
1
ST1 (NOR: ST CONT1)
ST signal to U44 for VCO
frequency band selection
#1 QB 2 ST2 ST signal to DDS (U42)
#2 QC 3 ST3 ST signal to DDS (U45)
#3 QD
4
ST (NOR: ST CONT1)
Used to generate latch timing
signal for U3 to U8
#4 QE 5 ST (NOR: ST CONT1) ST signal to PLL (U43)
#5 QF 6 N.C
#6 QG 7 N.C
U1
#7 QH 8 N.C
U2
9-16
N.C Not used
#15 QA 17 POWER data-1
#1 QB 18 POWER data-2
#2 QC 19 POWER data-3
#3 QD 20 POWER data-4
#4 QE 21 POWER data-5
#5 QF 22 POWER data-6
#6 QG 23 POWER data-7
U3
#7 QH 24 POWER data-8
D/A converted by R88 and
sent to Automatic Power
Control (APC) circuit to control
output power
#15 QA 25 N.C
#1 QB 26 N.C
#2 QC 27 RF GAIN data-1
#3 QD 28 RF GAIN data-2
#4 QE 29 RF GAIN data-3
#5 QF 30 RF GAIN data-4
#6 QG 31 RF GAIN data-5
U4
#7 QH 32 RF GAIN data-6
D/A converted by R138 for RF
AGC voltage control
#16 Q1 33 PR8
#15 Q2 34 PR7
#14 Q3 35 PR6
#13 Q4 36 PR5
#12 Q5 37 PR4
#11 Q6 38 PR3
#10 Q7 39 PR2
U5
#9 Q8 40 PR1
Selects capacitors in the
tuning circuit for 1.45 to 4.99
MHz band on PRESEL board
(05P0746)
#16 Q1 41 BPF2 (1.45 to 4.99 MHz)
#15 Q2 42 BPF5 (18 to 30 MHz)
#14 Q3 43 BPF4 (8 to 18 MHz)
#13 Q4 44 BPF3 (5 to 8 MHz)
#12 Q5 45 BPF1 (0.1 to 1.45 MHz)
Selects a filter (BPF) on
PRESEL board (05P0746)
#11 Q6 46 N.C
#10 Q7 47 N.C
U6
#9 Q8 48 N.C