Table of Contents
Advertisement
TM-V7A/E
CIRCUIT DESCRIPTION
Digital Control Circuit
The digital control section controls each function with
one microprocessor (IC508) and comprises the subtone
signal, DTMF encode and DTMF decode circuit (IC506), the
electronic control circuit (IC504), and the analog signal
select cross point switch (IC503 and 1C510) circuit.
The
reset and backup circuits, mic amp circuit, and microphone
key input circuit are also included in the control unit.
IC508
78P058GC
SI
Control panel
Panel and Control Unit Data Communications
Figure 7 shows the control unit data communication
circuits. Sl is the serial data in and SO is the serial data out.
There is an inverter for protecting the microprocessor board.
Data communication is asynchronous, with a communi-
cations speed of 3125 bps.
The control unit side micro-
processor checks the connection once every 0.5 second
and if the connection is NG twice in a row, in other words if
the panel section is removed for more than one second, the
power is cut off.
IC4
|
|
pPD78058GC
Panel surface
Fig.7 Panel, control unit data communications circuit
Speaker Switching Circuit
There are two speaker jacks, J1 and J2. The AF signals
can be output in various combinations matching the internal
speakers.
When no external speaker is connected to J1, Pins 10
and 11 of the multiplexer (IC18: XBU4053BCF) go low, the
AF signals AO 0 and AO 1 from the control unit are added
and input to the power amp (IC1: LA4446).
When an external speaker is connected to J1, Pins 10
and 11 of the multiplexer (1C18) go high and AO 0 and AO 1
are input separately to the power amp.
The AF signal output combinations are as in the speaker
combination cable on the right.
AOO
AO1
Internal speaker
external speaker
Internal speaker | external speaker
external speaker | external speaker
Internal speakers only
1 external speaker (J2)
1 external speaker (J1)
2 external speaker
Speaker combination table
ICt
POWER AMP
Ri2
R10
AO1
AN
AN
u
I>
8
1C18
a
o
15]
8
A
°
1 |
[40
12
R14
14
RQ
_ AAA
AOO
Wr
"TS
13
w—?
hM_{8
A
11
~
fem
Dé
f.
KHKH-+
PNA
2s
c>
7
Fig.8 Speaker switching circuit
Advertisement
Table of Contents
