Panasonic KX-NT321RU (serv.man2) Service Manual ▷ View online
5
KX-NT321RU
4 Technical Descriptions
4.1.
Block Diagram
KX-NT321
RU
Block Diagram
nRS
T
_
P
H
Y
nRS
T
_
P
H
Y
JK1
X1
TX
_C
LK
DC/
DC
+5
.0
V
+3.3V
Et
he
rne
t I/F
25.
00
MH
z
PU
L
S
E
T
rans
T2
RJ
45
To
L
A
N
10/
100B
ase-t
To
P
C
10/
100B
ase-t
RJ
45
PU
L
S
E
T
rans
T1
X2
R
E
G(3.
3V
)
+9V
DC I
N
DC
AL
AR
M
IC
1
0
IC31
KE
Y/
L
E
D
/L
C
D
A
n
alog I
/F
CRS
TX
_C
LK
R
X
_C
LK
COL
MA
C
2
M
II2
T
X
_E
N,T
X
_E
R, TXD [3:0]
CRS
RX
_DV, RX_ER, RXD [3:0]
R
X
_C
LK
COL
MA
C
1
M
II1
Data B
u
s
SIO
GP
IO
IC
1
3
LCD
Q6
IC
2
8
IC24
IC
2
0
IC
2
0
Heads
et
Q1
1
IC
2
3
IC
2
1
IC28
SW
HS
_
IN
HS
_
O
UT
MIC
_I
N
SP
_
O
UT
G722
MU
T
E
_S
P
M
U
TE_
SP2
GP
IO
CN6
IC
1
2
IC
8
IC
5
IC
4
MU
T
E
_
SP0
Q12
JK5
Q13
Hands
et
SW
Q10
Q14
IC22
MI
C
SP
CN4
CN5
JK4
LE
D
SP-DATA, SP_CLK, SP_LCK
LC
D
_
C
O
NT1, LCD_CONT2
LCD_DA
T
A
,L
CD_S
T
B
,L
CD_
S
C
K
Ke
y
KE
Y_OUT [6:0]
JK
2
CN8
CN7
RJ1
1
REG(1.5V)
IC
1
1
IC29
IC
1
Vo
IP
/D
S
P
+48V
8.
192
MH
z
R
ESE
Tn
IN
T
A
d
dres
s B
u
s
LE
D_CO1,
CO2,
M
E
S
,I
C
M
,D
IA
L
,A
NS
,S
P
E
thernet
PH
Y
(K
S
Z
8041)
IC
6
E
thernet
PH
Y
(K
S
Z
8041)
IC
7
Po
w
er
I/
F
Po
E ch
ip
IC
9
A
nal
og
IF
S
DRA
M
8M
byt
e
FL
ASH
4M
byt
e
Res
et
IC
IC3
IC
2
KE
Y_IN [5:0]
T
X
_E
N,T
X
_E
R, TXD [3:0]
RX
_DV, RX_ER, RXD [3:0]
+3.3V
+1.5V
REG(
3.
3V)
6
KX-NT321RU
4.2.
Circuit Operations
4.2.1.
CPU (IC1)
The DSP, MAC, CODEC and the CPU are built into the VoIP (IC1).
The FLASH (IC2) and the SDRAM (IC3) are connected to the CPU. The contents of the FLASH are expanded to the SDRAM at
start-up. It also stores each setting.
If the LCD is not displayed in the operation but there is no problem on the LCD, then the failure of the CPU system memory (IC2
and IC3) should be considered.
The FLASH (IC2) and the SDRAM (IC3) are connected to the CPU. The contents of the FLASH are expanded to the SDRAM at
start-up. It also stores each setting.
If the LCD is not displayed in the operation but there is no problem on the LCD, then the failure of the CPU system memory (IC2
and IC3) should be considered.
4.2.2.
LCD Circuit
LCD data are output from pin 138 of IC1 to LCD module.
IC12 is an inverter for a charge pump circuit which outputs the voltage necessary for LCD driving.
LCD contrast is set by electronic volume - IC1 - pin142 and pin143.
KX-NT321 uses a 16 digits x 1 lines LCD.
IC12 is an inverter for a charge pump circuit which outputs the voltage necessary for LCD driving.
LCD contrast is set by electronic volume - IC1 - pin142 and pin143.
KX-NT321 uses a 16 digits x 1 lines LCD.
7
KX-NT321RU
4.2.3.
Reset Circuit
Reset Signal is output from IC4 and input into IC1 and IC2.
4.2.4.
Ethernet Circuit
The Ethernet hub IC (IC6, IC7) is used for the Ethernet interface.
It is connected from IC6 to the Ethernet port (JK2) through a transformer and so is isolated.
Also, LAN port (JK2) gets power from the Ethernet line for PoE (Power over Ethernet) as shown below.
It is connected between IC7 and the VoIP (IC1) by high-speed bus called MII (Media Independent Interface) bus operating with
25MHz.
It is connected from IC6 to the Ethernet port (JK2) through a transformer and so is isolated.
Also, LAN port (JK2) gets power from the Ethernet line for PoE (Power over Ethernet) as shown below.
It is connected between IC7 and the VoIP (IC1) by high-speed bus called MII (Media Independent Interface) bus operating with
25MHz.
8
KX-NT321RU
4.2.5.
Analog Circuit
This circuit performs the setting of the call path/vol. adjustment in each call mode by a built-in DSP of VoIP(IC1).The audio gain
of each call is determined by download data from PBX or by internal data from flash memory(IC2).
In case of the extension call between NT300 series, The telephone call uses G722 codec.
of each call is determined by download data from PBX or by internal data from flash memory(IC2).
In case of the extension call between NT300 series, The telephone call uses G722 codec.
1. Handset Call
Transmitting signal is input from handset microphone, and amplified by IC24
→ input to IC1-pin112 → A/D conversion and
Gain adjustment by a built-in DSP of IC1
→ then sent to PBX.
Transmitting signal input from handset microphone is controlled by transmission switching SW IC29 as follows;
IC29-pin5 L: Handset Call
(IC29-pin5 H: Headset Call)
Transmitting signal input from PBX
IC29-pin5 L: Handset Call
(IC29-pin5 H: Headset Call)
Transmitting signal input from PBX
→ Gain adjustment by a built-in DSP.
Receiving signal input from PBX
→ Gain adjustment by a built-in DSP of IC1 → D/A conversion and output from IC1-pin115.
→ Amplified by IC20, and output to handset.
2. Headset Call
Transmitting signal is input from headset microphone, and amplified by IC24
→ input to IC1-pin112 → A/D conversion and
Gain adjustment by a built-in DSP of IC1
→ then sent to PBX.
Transmitting signal input from headset microphone is controlled by transmission switching SW IC29 as follows;
IC29-pin5 H: Headset Call
(IC29-pin5 L: Handset Call)
IC29-pin5 H: Headset Call
(IC29-pin5 L: Handset Call)
Receiving signal input from PBX
→ Gain adjustment by a built-in DSP of IC1 → D/A conversion and output from IC1-pin115.→
Amplified by IC20, and output to headset.
3. Speakerphone Call
Speakerphone call realize a full duplex call by a built-in DSP (echo-canceller) of IC1. For a call In the most appropriate condi-
tion, DSP checks voice level of the calling party, acoustics in a room, voice level of the other party and state of the line of con-
tact, and cancels echo in transmitting and receiving at the start of calling. It operates in a half duplex state in a few seconds for
the check.
tion, DSP checks voice level of the calling party, acoustics in a room, voice level of the other party and state of the line of con-
tact, and cancels echo in transmitting and receiving at the start of calling. It operates in a half duplex state in a few seconds for
the check.
Transmitting signal is input from microphone and amplified by IC23
→ input to IC1-pin113 → A/D conversion and Gain adjust-
ment by a built-in DSP of IC1, then sent to PBX through echo canceller.
Receiving signal input from PBX
→ Gain adjustment by DSP through a built-in echo canceller of IC1 → D/A conversion and
output from IC1-pin116
→ Amplified by IC21 and output to Speaker.
Power Amp IC21 is controlled as follows;
IC21-pin1 L: MUTE OFF
IC21-pin1 H: MUTE ON
IC21-pin1 L: MUTE OFF
IC21-pin1 H: MUTE ON
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