Furuno FM-8800D - Page 160

5.4 Block Description
5-28
U13 is IC that switches MIC and SP line. There are two different switch functions as
below.
- X and Y (linked function) : switch between a normal state and DTMF(Not used)
- Z : ON/OFF switch of loud speaker.
Fig. 5.4.23 MIC/SP Switching Block Diagram
CPU
Loudspeaker
(Handfree)
U2:
U6
Vol.
CONT.
Mulutiplexer
U13: TC4053
Earspeaker
(Handset)
U5
U5
U4
U7
U1
A
B
C
Z0
Z1
Y0
Y1
X0
Zcom
Ycom
Xcom
X1
DTMF
Line out
Handset MIC
Line in
Mute
R34