Panasonic KX-TG7120FXT User manual

© 2006 Panasonic Communications Co., Ltd. All
rights reserved. Unauthorized copying and distribu-
tion is a violation of law.
ORDER NO. KM40606102CE
Telephone Equipment
KX-TG7120FXS
KX-TG7120FXT
KX-TGA711FXS
KX-TGA711FXT
Digital Cordless Answering System
Silver Version
Titanium Black Version
(for Central Europe)

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
TABLE OF CONTENTS
PAGE PAGE
1 Safety Precaution ------------------------------------------------ 4
1.1. For Service Technicians --------------------------------- 4
2 Warning -------------------------------------------------------------- 4
2.1. Battery Caution--------------------------------------------- 4
2.2. About Lead Free Solder (Pbf: Pb free)--------------- 4
3 Specifications ----------------------------------------------------- 6
4 Technical Descriptions ----------------------------------------- 7
4.1. Block Diagram (Base Unit)------------------------------ 7
4.2. Circuit Operation (Base Unit)--------------------------- 8
4.3. Block Diagram (Handset)-------------------------------11
4.4. Circuit Operation (Handset)----------------------------12
4.5. Circuit Operation (Charger Unit)----------------------13
4.6. Signal Route -----------------------------------------------14
5 Location of Controls and Components ------------------16
5.1. Controls -----------------------------------------------------16
6 Installation Instructions ---------------------------------------16
6.1. Connections------------------------------------------------16
6.2. Battery-------------------------------------------------------17
7 Operation Instructions-----------------------------------------19
7.1. Base Unit Settings----------------------------------------19
7.2. Handset Settings -----------------------------------------20
7.3. Registering a Handset to the Base Unit ------------21
7.4. For Service Hint-------------------------------------------22
8 Service Mode -----------------------------------------------------23
8.1. Engineering Mode ----------------------------------------23
9 Troubleshooting Guide ----------------------------------------27
9.1. Troubleshooting Flowchart -----------------------------27
9.2. Troubleshooting by Symptom (Base Unit and
Charger Unit) ----------------------------------------------36
9.3. Troubleshooting by Symptom (Handset) -----------40
9.4. How to Replace the Flat Package IC----------------43
9.5. How to Replace the LLP (Leadless Leadframe
Package) IC------------------------------------------------45
10 Disassembly and Assembly Instructions ---------------47
10.1. Disassembly Instructions -------------------------------47
10.2. How to Replace the Handset LCD -------------------50
11 Measurements and Adjustments---------------------------51
11.1. The Setting Method of JIG (Base Unit) -------------51
11.2. Adjustment Standard (Base Unit)---------------------53
11.3. Adjustment Standard (Charger Unit)-----------------54
11.4. The Setting Method of JIG (Handset) ---------------55
11.5. Adjustment Standard (Handset) ----------------------57
11.6. Things to Do after Replacing IC ----------------------58
11.7. RF Specification-------------------------------------------59
11.8. How to Check the Handset Speaker of
Receiver ----------------------------------------------------60
11.9. Frequency Table (MHz) ---------------------------------60
12 Schematic Diagram ---------------------------------------------61
12.1. For Schematic Diagram---------------------------------61
12.2. Schematic Diagram (Base Unit_Main) --------------62
12.3. Schematic Diagram (Base Unit_Operation) -------64
12.4. Schematic Diagram (Handset) ------------------------66
12.5. Schematic Diagram (Charger Unit) ------------------68
13 Printed Circuit Board-------------------------------------------69
13.1. Circuit Board (Base Unit_Main)-----------------------69
13.2. Circuit Board (Base Unit_Operation) ----------------71
13.3. Circuit Board (Handset) ---------------------------------73
13.4. Circuit Board (Charger Unit) ---------------------------75
14 Appendix Information of Schematic Diagram --------- 76
14.1. CPU Data (Base Unit) ---------------------------------- 76
14.2. CPU Data (Handset) ------------------------------------ 78
14.3. Terminal Guide of the ICs, Transistors and
Diodes ------------------------------------------------------ 80
15 Exploded View and Replacement Parts List ----------- 81
15.1. Cabinet and Electric Parts (Base Unit) ------------- 81
15.2. Cabinet and Electric Parts (Handset) --------------- 82
15.3. Cabinet and Electric Parts (Charger Unit) --------- 83
15.4. Accessories and Packing Materials ----------------- 84
15.5. Replacement Part List ---------------------------------- 86

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
1 Safety Precaution
1.1. For Service Technicians
ICs and LSIs are vulnerable to static electricity.
When repairing, the following precautions will help prevent recurring malfunctions.
1. Cover the plastic parts boxes with aluminum foil and ground them.
2. Ground the soldering irons.
3. Use a conductive mat on the worktable.
4. Do not touch IC or LSI pins with bare fingers.
2Warning
2.1. Battery Caution
1. Danger of explosion if battery is incorrectly replaced.
2. Replace only with the same or equivalent type recommended by the manufacturer.
3. Dispose of used batteries according to the manufacture’s Instructions.
2.2. About Lead Free Solder (Pbf: Pb free)
Note:
In the information below, Pb, the symbol for lead in the periodic table of elements, will refer to standard solder or solder that con-
tains lead.
We will use PbF solder when discussing the lead free solder used in our manufacturing process which is made from Tin (Sn),
Silver (Ag), and Copper (Cu).
This model, and others like it, manufactured using lead free solder will have PbF stamped on the PCB. For service and repair
work we suggest using the same type of solder.
Caution
• PbF solder has a melting point that is 50 °F ~ 70 °F (30 °C ~ 40 °C) higher than Pb solder. Please use a soldering iron with
temperature control and adjust it to 700 °F ± 20 °F (370 °C ± 10 °C).
• Exercise care while using higher temperature soldering irons.:
Do not heat the PCB for too long time in order to prevent solder splash or damage to the PCB.
• PbF solder will tend to splash if it is heated much higher than its melting point, approximately 1100 °F (600 °C).
• When applying PbF solder to double layered boards, please check the component side for excess which may flow onto the
opposite side (See the figure below).

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
2.2.1. Suggested PbF Solder
There are several types of PbF solder available commercially. While this product is manufactured using Tin, Silver, and Copper
(Sn+Ag+Cu), you can also use Tin and Copper (Sn+Cu) or Tin, Zinc, and Bismuth (Sn+Zn+Bi). Please check the manufacturer’s
specific instructions for the melting points of their products and any precautions for using their product with other materials.
The following lead free (PbF) solder wire sizes are recommended for service of this product: 0.3 mm, 0.6 mm and 1.0 mm.
2.2.2. How to Recognize that Pb Free Solder is Used
(Example: Handset P.C.B.)
(Component View)
Note:
The location of the “PbF” mark is subject to change without notice.
PbF
C26 C39
110
16
17
11
32 27
26
IC1
IC3
IC4
1
80
20
21
4061
41
60
1
4
8
5
A
Marked

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
3 Specifications
Note:
• Specifications are subject to change.
Connections:
• The unit will not work during a power failure. We recommend you connect a standard telephone on the same line for power pro-
tection.
Note for Service:
•Operation range: Up to 300 m outdoors, Up to 50 m indoors
•Analog telephone connection: Telephone Line

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
4 Technical Descriptions
4.1. 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
CPU
59 54
61
52 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
TXDA
RXDA
15
21
20
22
RSSI SYCL SYDA SYEN
ANT1 ANT2
RF Module
18
16
2
31
8
21
14
13 12
12
13
XTAL
X1
10.368 MHz
EEPROM
SCL
SDA
6
5
To AC Adaptor
CN2
Limit
Resistor
CHARGE CONTACT
VUNREG
3.3V
Reg. IC1
2.5V
Reg. Q9
1.8V
Reg. Q8
3.3V 2.5V
1.8V
BBIC
IC5
FLASH
MEMORY
(TAM)
TAM Companion IC
RESET
CS
CS
10 11 12 13 14
SCK
SI SO
9
39 40 38 36 37 62
10 11 23 12
IC9
IC8
IC7
IC10
KX-TG7120 BLOCK DIAGRAM (BASE UNIT)

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
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.)
• FLASH MEMORY: IC9
- Voice Prompt (TAM) D/L Area
- ICM/OGM/MEMO Recording Area
• TAM Companion: IC8
- Voice data compression and decompression
- Speaker Amp
-LEDDriver
• 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-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
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 →Q9 →IC10 (PLL)
CN2 (+6.5 V) →IC1 →Q10 →IC10 (Power AMP)
• EEPROM (IC5):
CN2 (+6.5 V) →IC1 →Q9 →IC5
• FLASH MEMORY (IC9):
CN2 (+6.5 V) →IC1 →IC9
• TAM Companion (IC8):
CN2 (+6.5 V) →IC1 →Q9 →IC8
CN2 (+6.5 V) →IC1 →Q8 →IC8
• Charge Contact (TP16):
CN2 (+6.5 V) →R55, R56 →TP16
<Fig.101>
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]

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
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 Dialing
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-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
4.3. Block Diagram (Handset)
SPEAKER
RECEIVER
MIC
CHARGE
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
RS
RESET
CS
SI
SCL
CPU
Analog
Front
End
D/A
A/D
30
32
66
67
72
62
52
45
44
58
56
59
60
6
9
10
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
Ringer LED
7
75
46
KX-TGA711 BLOCK DIAGRAM (HANDSET)

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
4.4. Circuit Operation (Handset)
4.4.1. Outline
Handset consists of the following ICs as shown in Block Diagram (Handset) (P.11).
• DECT BBIC (Base Band IC): IC1
- All data signals (forming/analyzing ACK or CMD signal)
- All interfaces (ex: Key, Detector Circuit, Charge, DC/DC Converter, EEPROM, LCD)
• RF Module: IC4
- PLL Oscillator
-Detector
- Compress/Expander
- Amplifier for transmission and reception
• EEPROM: IC3
- Temporary operating parameters (for RF, etc.)
4.4.2. Power Supply Circuit/Reset Circuit
Circuit Operation:
When power on the Handset, the voltage is as follows;
BATTERY(2.2 V ~ 2.6 V: J1) →F1, L1, D1 →Q2 (1.8 V), Q3 (2.5 V), Q1 (3.3 V)
The Reset signal generates IC1 (66 pin) and 1.8 V.
4.4.3. Charge Circuit
Circuit Operation:
When charging the handset on the Base Unit, the charge current is as follows;
DC+(6.5 V) →R55, R56 →CHARGE+(Base) →CHARGE+(Handset) →L4 →Q4 →D7→F1 →BATTERY+... Battery...
BATTERY- →R45 →GND →L5 →CHARGE-(Handset)→CHARGE-(Base) →GND →DC-(GND)
In this way, the BBIC on Handset detects the fact that the battery is charged.
The charge current is controlled by switching Q5 of Handset.
Refer to Fig.101 in Power Supply Circuit (P.9).
4.4.4. Battery Low/Power Down Detector
Circuit Operation:
“Battery Low” and “Power Down” are detected by BBIC which check the voltage from battery.
The detected voltage is as follows;
• Battery Low
Battery voltage: V(Batt) 2.25 V ± 50 mV
The BBIC detects this level and " " starts flashing.
• Power Down
Battery voltage: V(Batt) 2.0 V ± 50 mV
The BBIC detects this level and power down.
4.4.5. Speakerphone
The hands-free loudspeaker at SP+ and SP- is used to generate the ring alarm.

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
4.5. Circuit Operation (Charger Unit)
4.5.1. Power Supply Circuit
The power supply is as shown.

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
4.6. Signal Route

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
5 Location of Controls and
Components
5.1. Controls
5.1.1. Base Unit
5.1.2. Handset
6 Installation Instructions
6.1. Connections
Base unit
When connecting the AC adaptor to the base unit, a short
beep will be heard. If it is not heard, check the connections.
Charger
Connect the AC adaptor to the charger and route the cable
as shown. The charger can be mounted on the wall, if
required.
Note:
• Never install telephone wiring during a lightning storm.
• The AC adaptor must remain connected at all times. (It is
normal for the adaptor to feel warm during use.)
• The AC adaptor should be connected to a vertically oriented
or floor-mounted AC outlet. Do not connect the AC adaptor
to a ceiling-mounted AC outlet, as the weight of the adaptor
may cause it to become disconnected.
Location
• For maximum distance and noise-free operation, place your
base unit:
- away from electrical appliances such as TVs, radios,
personal computers or other phones.
- in a convenient, high and central location.

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
6.2. Battery
6.2.1. Battery Installation/Replacement
Important:
• Use only the included rechargeable batteries HHR-55AAAB
or HHR-4EPT.
• When replacing batteries, we recommend using the
Panasonic rechargeable batteries P03P.
Notice:
When inserting the batteries:
• Wipe the battery ends ( , ) with a dry cloth.
• Install the batteries without touching the battery ends ( ,
) or the unit contacts.
I fullly charged the batteries, but the operating time
seems to be short:
• Wipe the battery ends ( , ) and the unit contacts with a
dry cloth.
6.2.2. Battery Charge
Place the handset on the base unit or charger for about
7 hours before initial use.
When charging, the battery icon is shown as follows.
When the batteries are fully charged, remains on the
display.
• The charge indicator lights up when the handset is placed on
the base unit or charger.
Note:
• It is normal for the handset to feel warm during charging.
• If you want to use the unit immediately, charge the batteries
for at least 15 minutes.
• Clean the charge contacts of the handset, base unit, and
charger with a soft, dry cloth, otherwise the batteries may
not charge properly. Clean if the unit is exposed to grease,
dust or high humidity.
6.2.3. Battery Strength

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
6.2.4. Panasonic Ni-MH Battery
Performance (included batteries)
Note:
• It is normal for batteries not to reach full capacity at the initial
charge. Maximum battery performance is reached after a
few complete cycles of charge/discharge (use).
• Actual battery performance depends on a combination of
how often the handset is in use and how often it is not in use
(standby).
• Battery operating time may be shortened over time
depending on usage conditions and ambient temperature.
• Even after the handset is fully charged, the handset can be
left on the base unit or charger without any ill effect on the
batteries.
• The battery strength may not be displayed correctly after you
replace the batteries. In this case, place the handset on the
base unit or charger and charge for at least 7 hours.

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
7 Operation Instructions
7.1. Base Unit Settings
• Use the handset to customise the base unit.
• When customising the base unit, the current item or setting is indicated by .
*1 Change the recall time, if necessary, depending on the requirements of your service provider/telephone company or PBX.
*2 The default setting will be as follows if you select the following regional codes when changing the unitís region setting:
CZ=100 msec.
SK=100 msec.
*3 If you forget your PIN, see For Service Hint (P.22).
*4 If you change the PIN, please make note of your new PIN. The unit will not reveal the PIN to you.
*5 The items are not shown on the display.
7.1.1. SMS Settings
If the base unit is reset to its default settings, the following SMS-related settings will be reset. The contents of the receive and
send lists will be erased.
*1 If you set the unit’s region setting to “CZ” or “SK”, the default setting is “On”.
7.1.2. Answering System Settings
If the base unit is reset to its default settings, the following answering systemrelated settings will be reset.

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KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT
7.2. Handset Settings
Cross Reference:
Registering a Handset to the Base Unit (P.21)
Base Unit Settings (P.19)