Tx/Rx Pcb; Cpu Pcb - Furuno FM-8800D Service Manual

2. TX/RX PCB

This is to check the unlocked state of PLL circuit on TX/RX board (05P0774A, B).
Frequency to be checked is the frequency set up at the time of self-test. The
Un-lock/Lock signal is outputted from U12: PLL IC on TX/RX board. PLL circuit on
this board is used with both TX and RX. Tx Local frequency is Fo + 45 MHz, and RX
Local frequency is Fo + 51.2375 MHz.
PA
DRIVE
Tx out
U1 Q1,5
2SK3874
RA35H1516M
2SC3356

3. CPU PCB

This is a loop-back test where test signal is transmitted from U17: CODEC on CPU
board (05P0773) and is detected by U10: CODEC. A signal transmitted from U17 is
sine wave of 2 kHz. If this frequency and a designated level are detected by U10, it will
be assessed "OK''. U25: DDS check is carried out the same way and a test signal is
transmitted from DDS. U17 digitizes (A/D conversion) IF signal of 37.5 kHz
transmitted from CH70 RX board, TX/RX board and DUP RX board. U10 on the other
hand, digitizes (A/D, D/A conversion) mainly LINE input/output and AF input/output
from a Remote Handset. Refer to page 8-16 for DDS/CODEC test which takes the same
procedure.
TX/RX
05P0774
U5
TA4001
Tx Local
MIX
BPF(L/C)
(F0+45 MHz)
F0
Q101
SW
CR101
PMBF J310
ISS271
RX
Rx 1st Lo
circuit (Fo+51.2375MHz)
Rx 2nd Lo
(51.2MHz)
Fig. 8.1.2 TX/RX PLL Block Diagram
CPU
05P0773
AOUT R CODEC
U17
AOUT L
(AK4528VF)
CODEC
VIDEO L
U10
VIDEO R
(AK4543)
Fig. 8.1.3 CPU PCB Test
FL1: 45MHz
U10
Rx 2nd Lo
TA4001
(51.2MHz)
VCO
U8
Q14, CR11/12
Q13
BPF(L/C)
uPC2745TB
2SC3356
2SC3356
1SV229
LPF
Q15
PMBF M310
PLL
U12
LMX2353TMX
CPU
DSP
8-2
8.1 Self-test and Error Message
45 MHz
X2
25.6MHz
Q20
Ref. OSC
U11
TC75HU04F
CPU
51.2MHz
PLL1 DATA(STB/DATA/CLK)
PLL1 UN-LOCK
Q21
U25
DDS
05P0773
U30
CPU