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Model
KX-TG8205RUB KX-TG8205RUJ KX-TG8205RUM KX-TG8205RUW KX-TG8206RUB KX-TG8206RUM KX-TG8206RUW KX-TGA820RUB KX-TGA820RUJ KX-TGA820RUM KX-TGA820RUW
Pages
95
Size
2.74 MB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS PHONE
File
kx-tg8205rub-kx-tg8205ruj-kx-tg8205rum-kx-tg8205ru.pdf
Date

Panasonic KX-TG8205RUB / KX-TG8205RUJ / KX-TG8205RUM / KX-TG8205RUW / KX-TG8206RUB / KX-TG8206RUM / KX-TG8206RUW / KX-TGA820RUB / KX-TGA820RUJ / KX-TGA820RUM / KX-TGA820RUW Service Manual ▷ View online

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KX-TG8205RUB/KX-TG8205RUJ/KX-TG8205RUM/KX-TG8205RUW/KX-TG8206RUB/KX-TG8206RUM/KX-TG8206RUW/KX-TGA820RUB/KX-TGA820RUJ/KX-TGA820RUM/KX-TGA820RUW
4.2.
Circuit Operation (Base Unit)
4.2.1.
Outline
Base unit consists of the following ICs as shown in Block Diagram (Base Unit) (P.7).
• DECT BBIC (Base Band IC): IC7
- 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 code 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: IC10
- PLL Oscillator
- Detector
- Compress/Expander
- First Mixer
- Amplifier for transmission and reception
• EEPROM: IC5
- Temporary operating parameters (for RF, etc.)
• Additionally,
- Power Supply Circuit (+3.3 V, +2.5 V, +1.8 V output)
- Crystal Circuit (10.368 MHz)
- Charge Circuit
- Telephone Line Interface Circuit
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KX-TG8205RUB/KX-TG8205RUJ/KX-TG8205RUM/KX-TG8205RUW/KX-TG8206RUB/KX-TG8206RUM/KX-TG8206RUW/KX-TGA820RUB/KX-TGA820RUJ/KX-TGA820RUM/KX-TGA820RUW
4.2.2.
Power Supply Circuit
The power is supplied to the DECT BBIC, RF Module, EEPROM and Charge Contact from AC Adaptor (+6.5 V) as shown in
Fig.101. The power supply is as follows;
• DECT BBIC (IC7): 
CN2 (+6.5 V) 
→ IC1 → Q9 → IC7
CN2 (+6.5 V) 
→ IC1 → Q8 → IC7
• RF Module (IC10): 
CN2 (+6.5 V) 
→ IC1 → Q8 → IC10 (Radio Transceiver) (Digital)
CN2 (+6.5 V) 
→ IC1 → Q9 → IC10 (Radio Transceiver) (Analog)
CN2 (+6.5 V) 
→ IC1 → R125 → IC10 (Power AMP)
• EEPROM (IC5): 
CN2 (+6.5 V) 
→ IC1 → Q9 → IC5
• Charge Contact (TP16): 
CN2 (+6.5 V) 
→ R57 → R56 → R55 → D22 → TP16
<Fig.101>
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KX-TG8205RUB/KX-TG8205RUJ/KX-TG8205RUM/KX-TG8205RUW/KX-TG8206RUB/KX-TG8206RUM/KX-TG8206RUW/KX-TGA820RUB/KX-TGA820RUJ/KX-TGA820RUM/KX-TGA820RUW
4.2.3.
Telephone Line Interface
<Function>
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
Bell & Clip (: Calling Line Identification Presentation: Caller ID) signal detection:
In the standby mode, Q3 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the L1T (A) and L1R (B) leads (when the telephone rings), the AC ring voltage is transferred as
follows;
• A 
→ C4 → R6 → R33 → IC7 Pin 60 (CID INp) 
• B 
→ C3 → R4 → R35 → IC7 Pin 52 (CID INn)
ON/OFF hook circuit:
In the standby mode, Q3 is open, and connected as to cut the DC loop current and to cut the voice signal. The unit is conse-
quently in an on-hook condition
When IC7 detects a ring signal or press the TALK Key onto the handset, Q4 turns on and then Q3 turns on, thus providing an
off-hook condition (DC current flows through the circuit) and the following signal flow makes the loop current.
• A 
→ D3 → Q3 → Q5 → R21 → R22 → D3 → B [OFF HOOK]
4.2.4.
Transmitter/Receiver
• Audio Circuits and DTMF tone signal circuits.
Base unit and handset mainly consist of RF Module and DECT BBIC. 
Base unit and handset transmit/receive voice signal and data signal through the antenna on carrier frequency.
Signal Path:
*Refer to Signal Route (P.14).
4.2.4.1.
Transmitter Block
The voice signal input from the TEL LINE interface goes to RF Module (IC10) through DECT BBIC (IC7) as shown in Block Dia-
gram (Base Unit) 
(P.7)
The voice signal passes through the analog part of IC7 where it is amplified and converted to a digital audio stream signal. The
burst switch controller processes this stream performing encryption and scrambling, adding the various other fields to produce
the GAP (Generic Access Profile) standard DECT frame, assigning to a time slot and channel etc.
In IC10, the carrier frequency is changing, and frequency modulated RF signal is generated and amplified, and radiated from
antenna. Handset detects the voice signal or data signal in the circuit same as the following explanation of Receiver Block.
4.2.4.2.
Receiver Block
The signal of 1900 MHz band (1881.792 MHz ~ 1897.344 MHz) which is input from antenna is input to IC10 as shown in Block
Diagram (Base Unit)
 (P.7).
In IC10, the signal of 1900 MHz band is downconverted to 864 kHz signal and demodulated, and goes to IC7 as GAP (Generic
Access Profile) standard DECT frames. It passes through the decoding section burst switch controller where it separates out the
frame information and performs de-encryption and de-scrambling as required. It then goes to the DSP section where it is turned
back into analog audio. This is amplified by the analog front end, and goes to the TEL LINE Interface.
4.2.5.
Pulse Dialling
During pulse dialing the hookswitch (Q3, Q4) is used to generate the pulses using the HOOK control signal, which is set high
during pulses. To force the line impedance low during the “pause” intervals between dial pulses, the PULSE_DIAL signal turns
on Q2.
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KX-TG8205RUB/KX-TG8205RUJ/KX-TG8205RUM/KX-TG8205RUW/KX-TG8206RUB/KX-TG8206RUM/KX-TG8206RUW/KX-TGA820RUB/KX-TGA820RUJ/KX-TGA820RUM/KX-TGA820RUW
4.3.
Block Diagram (Handset)
SPEAKER
RECEIVER
MIC
CN4
Headset
CHARGE
LOGIC IC
CIRCUIT
Q4,Q5,Q9
R7
CHARGE
CONTACTS
CHARGE(+)
CHARGE(-)
CHARGE
CHARGE DETECT
EEPROM
SCL
SDA
SWITCHED
SUPPLY
    Q1
Q1
BATTERY
TERMINAL
D7
VBAT1
DC/DC-SWITCH
J1
J2
2.5V
Q3
1.8V
Q2
4.0V
2.5V
1.8V
LCD
CD
RESET
CSB
SDA
 SCL
CPU
Analog
Front
End
D/A
A/D
18
25
MIDI_SCL
MIDI_SDA
MIDI_CS
27
19
1
10
9
7
19
13
17
66
67
72
62
52
45
44
 58
56
  59 
 60
6
47
46
77
ADPCM
Codec
Filter
DSP
Speech
Decoding
Speech
Encoding
BMC
Burst
Decoding
Burst
Encoding
RF
Interface
RF
Module
IC4
23
22
RXDA
TXDA
19
26
25
24
RSSI
SYDA
SYEN
SYCL
16
17
XTAL
X1
10.368
MHz
BATTERY
61
ON SWITCH
KEYPAD
ROWS
COLUMNS
1,12,40,76
27,28,34,35,36,74
BBIC
IC1
IC3
 11
LCD-BACK  LIGHT
KEY-BACK  LIGHT
5
1
2
3
4
5
16.9 M
MIDI
IC12
KX-TGA820  BLOCK DIAGRAM (HANDSET)
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