Ch70 Rx Pcb - Furuno FM-8800D Service Manual

4. CH70 RX PCB

Modulated signal 37.5 kHz of CH70 TEST signal is outputted from U17: CODEC on
CPU board. This test checks the test signal modulated by 1300 Hz and that modulated
by 2100 Hz. If the same signal transmitted from U17: CODEC on CPU board via R37
on CH70 RX board is detected, it will be assessed "OK''. "NG'' means there may be a
problem with CPU board (05P0773). Refer to page 8-12 for CH70 RX test which takes
the same procedure.
MIX
CR4
5. DUP RX PCB
This is indicated when FM-8800D is in use. This is to check the unlocked state of PLL
circuit on DUP RX board (05P0777). Frequency to be checked it is 161.5 MHz at the
time of self-test. The Un-lock/Lock signal is outputted from U8: PLL IC on DUP RX
board. "NG" means there may be a problem with DUP RX board.
st
RX 1 Lo is Fo + 51.2375 MHz.
BPF(L/C)
DUP RX
Q1
CH70 RX
J3
05P0775
#3 CH70 TEST
#5 CH70 IF OUT
37.5kHz
R36
Q7
Fig. 8.1.4 CH70 RX PCB Test
FL1
BPF(L/C)
(51.2375MHz)
Q13
CR10/11
PMBFJ310
ISS271
BPF(L/C)
uPC2745TB
2SC3356
DUP RX
05P0777
Fig. 8.1.5 DUP RX PLL Block Diagram
CPU
05P0773
J4
CODEC
37.5MHz
#3
U17
#5
(AK4528VF)
CODEC
U18
U10
(AK4543)
CR8/9
MA2J728
Q14
2SK882
Q4
VCO
U5
Q6, CR3/4
Q5
2SC3356
1SV229
LPF
Q11
PMBF M310
51.2MHz
PLL
PLL2 DATA(STB/DATA/CLK)
U8
Q10
LMX2353TMX
8-3
8.1 Self-test and Error Message
DSP CPU
U17
37.5kHz
Q14
CODEC
2SC3324
X2
25.6MHz
Ref. OSC
U3
TC75HU04F
CPU
05P0773
U30
CPU
PLL2 UN-LOCK