Panasonic KX-TCD225UA / KX-TCA122UA / KX-TCA121UA Service Manual ▷ View online
18 HOW TO CHECK THE HANDSET SPEAKER OR
RECEIVER
1. Prepare the digital voltmeter, and set the selector knob to ohm meter.
2. Put the probes at the speaker terminals as shown below.
19 FREQUENCY TABLE (MHz)
BASE UNIT
HANDSET
Channel No
Transmit Frequency
Receive Frequency
Transmit Frequency
Receive Frequency
1
1897.344
1897.344
1897.344
1897.344
2
1895.616
1895.616
1895.616
1895.616
3
1893.888
1893.888
1893.888
1893.888
4
1892.160
1892.160
1892.160
1892.160
5
1890.432
1890.432
1890.432
1890.432
6
1888.704
1888.704
1888.704
1888.704
7
1886.976
1886.976
1886.976
1886.976
8
1885.248
1885.248
1885.248
1885.248
9
1883.520
1883.520
1883.520
1883.520
10
1881.792
1881.792
1881.792
1881.792
Note:
Channel No. 10: In the Test Mode on Base Unit and Handset.
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KX-TCD225UA / KX-TCA122UA / KX-TCA121UA
20 BLOCK DIAGRAM (BASE UNIT)
Analog
Front
End
To TEL_LINE
A
B
CN1
Bridge
Rect D3
D3
Hook Switch
Q4,Q5
Audio
Bell/Caller ID
Interface
Analog
Switch
Switch
CPU
59
54
54
61
52
60
56
60
56
55
BELL
HOOK
Off-Hook Line Voltage
64 ADCO
D/A
A/D
ADPCM
Codec Filter
DSP
Speech Decoding
Speech Encoding
BMC
Burst Decoding
Burst Encoding
RF
Interface
18
19
RXDA
TXDA
15
21
20
22
RSSI
SYCL
SYDA
SYEN
SYCL
SYDA
SYEN
ANT1
ANT2
ANT2
RF Module
4
10
2
31
8
21
14
13
12
12
12
13
XTAL
X1
10.368
MHz
MHz
EEPROM
SCL
SDA
6
5
To AC Adaptor
CN1
Limit
Resistor
CHARGE
CONTACT
CONTACT
VUNREG
3.3V
Reg.
Reg.
IC1
2.5V
Reg.
Reg.
Q2
1.8V
Reg. Q3
Reg. Q3
3.3V
2.5V
1.8V
BBIC
IC3
FLASH
MEMORY
(TAM)
RESET
CS
23
36
SCK
SI
38
39
SO
40
IC5
IC8
IC2
KX-TCD225 BLOCK DIAGRAM (BASE UNIT)
KX
-T
CD2
25UA
/
KX
-T
C
C
A
122U
A
/
/
KX
-T
CA1
21UA
66
21 CIRCUIT OPERATION (BASE UNIT)
21.1. Outline
Base Unit consists of the following ICs as shown in BLOCK DIAGRAM (BASE UNIT) (P.66).
·
DECT BBIC (Base Band IC): IC8
−
−
−
−
Handling all the audio, signal and data processing needed in a DECT base unit
−
−
−
−
Controlling the DECT specific physical layer and radio section (Burst Module Controller section)
−
−
−
−
ADPCM codec filter for speech encoding and speech decoding (DSP section)
−
−
−
−
Echo-cancellation and Echo-suppression (DSP section)
−
−
−
−
Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
−
−
−
−
DTMF receiver (DSP section)
−
−
−
−
Clock Generation for RF Module
−
−
−
−
ADC, DAC, timer, and power control circuitry
−
−
−
−
All interfaces (ex: RF module, EEPROM, LED, Analog Front End, etc.)
·
RF Module: IC2
−
−
−
−
PLL Oscillator
−
−
−
−
Detector
−
−
−
−
Compress/Expander
−
−
−
−
First/Second Mixer
−
−
−
−
Amplifier for transmission and reception
·
EEPROM: IC3
−
−
−
−
Temporary operating parameters (for RF, etc.)
·
Additionally,
−
−
−
−
Power Supply Circuit (+3.3V, +2.5V, +1.8V output)
−
−
−
−
Crystal Circuit (10.368MHz)
−
−
−
−
Charge Circuit
−
−
−
−
Telephone Line Interface Circuit
·
FLASH MEMORY: IC5
−
−
−
−
Voice Prompt (TAM) D/L Area
−
−
−
−
ICM/OGM/MEMO recording area
67
KX-TCD225UA / KX-TCA122UA / KX-TCA121UA
21.2. Power Supply Circuit
The power is supplied to the DECT BBIC, RF Module, EEPROM and Charge Contact from AC Adaptor (+6V) as shown in
Fig.101. The power supply is as follows;
Fig.101. The power supply is as follows;
·
DECT BBIC (IC8):
CN1 (+6V)
→
D1
→
IC1
→
Q2
→
IC8
·
RF Module (IC2):
CN1 (+6V)
→
D1
→
IC1
→
Q2
→
IC2 (PLL)
CN1 (+6V)
→
D1
→
IC1
→
IC2 (Power AMP)
·
EEPROM (IC3):
CN1 (+6V)
→
D1
→
IC1
→
Q2
→
IC3
·
FLASH MEMORY (IC5):
CN1 (+6V)
→
D1
→
IC1
→
IC5
·
Charge Contact (TP15):
CN1 (+6V)
→
D1
→
R3, R5
→
TP15
<Fig.101>
68
KX-TCD225UA / KX-TCA122UA / KX-TCA121UA
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