Panasonic KX-TG7741S User manual

© Panasonic System Networks Co., Ltd. 2012
Unauthorized copying and distribution is a violation
of law.
ORDER NO. KM41201533CE
F13
Telephone Equipment
Model No. KX-TG7741S
KX-TG7742S
KX-TG7743S
KX-TGA470S
Link-to-Cell Cellular Convergence
Solution
S: Silver Version
(for U.S.A.)
(Handset)
KX-TGA470S KX-TG7741S
(Base Unit)
(Charger Unit)
Model No
Base Unit Handset Charger Unit Expandable
KX-TG7741
1 (TG7741) 1 (TGA470) Up to 6
KX-TG7742
1 (TG7741) 2 (TGA470) 1 Up to 6
KX-TG7743
1 (TG7741) 3 (TGA470) 2 Up to 6
KX-TGA470*
1 (TGA470) 1
Configuration for each model
*KX-TGA470 is also an optional accessory, which contains a
handset and a charger.

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
WARNING
This service information is designed for experienced repair technicians only and is not designed for use by the general
public. It does not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting
to service a product. Products powered by electricity should be serviced or repaired only by experienced professional
technicians. Any attempt to service or repair the product or products dealt with in this service information by anyone
else could result in serious injury or death.
IMPORTANT SAFETY NOTICE
There are special components used in this equipment which are important for safety. These parts are marked by
in the Schematic Diagrams, Circuit Board Diagrams, Exploded Views and Replacement Parts List. It is essential that
these critical parts should be replaced with manufacturer’s specified parts to prevent shock, fire or other hazards.
Do not modify the original design without permission of manufacturer.
IMPORTANT INFORMATION ABOUT LEAD FREE, (PbF), SOLDERING
If lead free solder was used in the manufacture of this product, the printed circuit boards will be marked PbF.
Standard leaded, (Pb), solder can be used as usual on boards without the PbF mark.
When this mark does appear, please read and follow the special instructions described in this manual on the
use of PbF and how it might be permissible to use Pb solder during service and repair work.
LWhen you note the serial number, write down all 11 digits. The serial number may be found on the bottom of the unit.
LThe illustrations in this Service Manual may vary slightly from the actual product.

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
TABLE OF CONTENTS
PAGE PAGE
1 Safety Precautions----------------------------------------------- 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
2.3. Discarding of P. C. Board-------------------------------- 5
3 Specifications ----------------------------------------------------- 6
4 Technical Descriptions ----------------------------------------- 7
4.1. Circuit Configuration of TG774x Series
Phones ------------------------------------------------------- 7
4.2. US-DECT Description ------------------------------------ 8
4.3. Block Diagram (Base Unit_Main)---------------------10
4.4. Tel Interface Circuit---------------------------------------11
4.5. Block Diagram (Base Unit_RF Part) -----------------12
4.6. Circuit Operation (Base Unit)--------------------------13
4.7. Block Diagram (Handset)-------------------------------20
4.8. Block Diagram (Handset_RF Part)-------------------21
4.9. Circuit Operation (Handset)----------------------------22
4.10. Circuit Operation (Charger Unit) ----------------------23
4.11. Signal Route -----------------------------------------------24
5 Location of Controls and Components ------------------26
6 Installation Instructions ---------------------------------------26
7 Operating Instructions-----------------------------------------26
8 Test Mode ----------------------------------------------------------27
8.1. Engineering Mode ----------------------------------------27
9 Service Mode -----------------------------------------------------31
9.1. How to Clear User Setting (Handset Only)---------31
10 Troubleshooting Guide ----------------------------------------32
10.1. Troubleshooting Flowchart -----------------------------32
11 Disassembly and Assembly Instructions ---------------48
11.1. Disassembly Instructions -------------------------------48
11.2. How to Replace the Base unit LCD------------------52
11.3. How to Replace the Handset LCD -------------------54
12 Measurements and Adjustments---------------------------55
12.1. Equipment Required -------------------------------------55
12.2. The Setting Method of JIG -----------------------------55
12.3. Adjustment Standard (Base Unit)---------------------59
12.4. Adjustment Standard (Charger Unit)-----------------60
12.5. Adjustment Standard (Handset) ----------------------61
12.6. Things to Do after Replacing IC or X'tal ------------62
12.7. Frequency Table ------------------------------------------64
12.8. Bluetooth Frequency Table-----------------------------65
13 Miscellaneous ----------------------------------------------------66
13.1. How to Replace the LLP (Leadless Leadframe
Package) IC------------------------------------------------66
13.2. How to Replace the Flat Package IC----------------68
13.3. Terminal Guide of the ICs, Transistors and
Diodes -------------------------------------------------------70
14 Schematic Diagram ---------------------------------------------71
14.1. For Schematic Diagram---------------------------------71
14.2. Schematic Diagram (Base Unit_Main) --------------72
14.3. Schematic Diagram (Base Unit_RF)-----------------74
14.4. Schematic Diagram (Base Unit_Operation) -------75
14.5. Schematic Diagram (Handset_Main) ----------------76
14.6. Schematic Diagram (Handset_LED)-----------------78
14.7. Schematic Diagram (Charger Unit) -----------------79
15 Printed Circuit Board-------------------------------------------81
15.1. Circuit Board (Base Unit_Main)-----------------------81
15.2. Circuit Board (Base Unit_Operation)---------------- 83
15.3. Circuit Board (Handset_Main) ------------------------ 84
15.4. Circuit Board (Handset_LED)------------------------- 86
15.5. Circuit Board (Charger Unit)--------------------------- 87
16 Exploded View and Replacement Parts List ----------- 88
16.1. Cabinet and Electrical Parts (Base Unit) ----------- 88
16.2. Cabinet and Electrical Parts (Handset)------------- 89
16.3. Cabinet and Electrical Parts (Charger Unit)------- 90
16.4. Accessories and Packing Materials ----------------- 91
16.5. Replacement Parts List--------------------------------- 95

4
KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
1 Safety Precautions
1.1. For Service Technicians
•Repair service shall be provided in accordance with repair technology information such as service manual so as to
prevent fires, injury or electric shock, which can be caused by improper repair work.
1. When repair services are provided, neither the products nor their parts or members shall be remodeled.
2. If a lead wire assembly is supplied as a repair part, the lead wire assembly shall be replaced.
3. FASTON terminals shall be plugged straight in and unplugged straight out.
•ICs and LSIs are vulnerable to static electricity.
When repairing, the following precautions will help prevent recurring malfunctions.
1. Cover plastic parts boxes with aluminum foil.
2. Ground the soldering irons.
3. Use a conductive mat on worktable.
4. Do not grasp IC or LSI pins with bare fingers.
2Warning
2.1. Battery Caution
Risk of explosion if battery is replaced by an incorrect type. Dispose of used batteries according to the instructions.
Attention:
A nickel metal hydride battery that is recyclable powers the product you have purchased.
Please call 1-800-8-BATTERY (1-800-822-8837) for information on how to recycle this battery.
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
contains 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).
Component
Component
pin
Solder
Remove all of the
excess solder
(Slice View)

5
KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
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.
2.3. Discarding of P. C. Board
When discarding P. C. Board, delete all personal information such as telephone directory and caller list or scrap P. C. Board.
0.3 mm X 100 g 0.6 mm X 100 g 1.0 mm X 100 g

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
3 Specifications
Note:
• Design and specifications are subject to change without notice.
Note for Service:
•Operation range: Up to 300 m outdoors, Up to 50 m indoors, depending on the condition.
•Analog telephone connection: Telephone Line
•Optional headset: KX-TCA60, KX-TCA93, KX-TCA400, KX-TCA430
•Optional Range extender: KX-TGA405
Power source
Receiving Method
Oscillation Method
Detecting Method
Tolerance of OSC Frequency
Modulation Method
ID Code
Ringer Equivalence No. (REN)
Dialing Mode
Redial
Speed Dialer
Power Consumption
Operating Conditions
Dimensions (W x D x H)
Mass (Weight)
AC Adaptor
(PNLV226Z, 120 V AC, 60 Hz)
Super Heterodyne
PLL synthesizer
Quadrature Discriminator
10.368 MHz ±100 Hz
Frequency Modulation
40 bit
0.1B
Standby: Approx. 1.2 W
Maximum: Approx. 4.5 W
0 ˚C - 40 ˚C (32 ˚F – 104 ˚F)
20 % – 80 % relative air humidity
(dry)
Approx. 200 mm × 119 mm × 71 mm
Approx. 350 g
Rechargeable Ni-MH battery
AAA (R03) size (1.2 V 550 mAh)
Super Heterodyne
PLL synthesizer
Quadrature Discriminator
13.824 MHz ±100 Hz
Frequency Modulation
40 bit
Tone (DTMF)/Pulse
Up to 48 digits
Up to 24 digits (Phonebook)
11 days at Standby,
13 hours at Talk
0 ˚C - 40 ˚C (32 ˚F – 104 ˚F)
20 % – 80 % relative air humidity
(dry)
Approx. 54
mm × 34 mm × 174 mm
Approx. 150 g
Base Unit Handset Charger
AC Adaptor
(PNLV226Z, 120 V AC, 60 Hz)
Standby: Approx 0.1 W
Maximum: Approx 2.0 W
0 ˚C - 40 ˚C (32 ˚F – 104 ˚F)
20 % – 80 % relative air humidity
(dry)
Approx. 73 mm × 76 mm × 43 mm
Approx. 50 g
Duplex procedure:
TDMA (Time Division Multiple Access)
Channel spacing:
1.728MHz (DECT 6.0)
1.0MHz(Bluetooth)
Bit rate:
1.152Mbit/s (DECT 6.0)
1.0 Mbit/s (Bluetooth)
Modulation:
GFSK (Gaussian Frequency Shift Keying)
RF transmission power:
115 mW (max/DECT6.0)
Voice coding:
ADPCM 32 kbit/s (DECT 6.0)
Tone (DTMF)/Pulse
Up to 48 digits
CVSD/PCM 64kbit/s (Bluetooth)
PCM 64kbit/s(BT_IC)
■
■
■
■
■
■
■Standard:
DECT 6.0 (Digital Enhanced Cordless
Telecommunications 6.0)
■Number of channels:
60 Duplex Channels (DECT 6.0)
79 Duplex channels(Bluetooth)
Bluetooth wireless technology 2.0
■Frequency range:
1.92 GHz to 1.93 GHz (DECT 6.0)
2.402 GHz to 2.48 GHz (Bluetooth)

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
4 Technical Descriptions
4.1. Circuit Configuration of TG774x Series Phones
TG774x consists of DECT cordless telephone and Bluetooth Module.
Both voices of transmission and reception are transferred by PCM.
BBIC on DECT side controls the cordless telephone system, which makes control data communication with BT_IC on BT
Module in serial data.
DECT6.0
Bluetooth
Headset
Bluetooth Devices
Cellular Phone
(For Link to Cell
communication)
TGA470
Handset
PSTN DC
5.5V
BBIC
FLASH IC601
(TAM)
EEPROM IC611
(Data)
TEL I/F POWER
QSPI FLASH
IC502
(Program)
Main PCB
Audio signal
(PCM)
Control/Data
Bluetooth Bluetooth
signal
(UART)
BT_Module
(IC721)
(IC501)
MIC
SPEAKER

8
KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
4.2. US-DECT Description
The frequency range of 1.92 GHz-1.93 GHz is used. Transmitting and receiving carrier between base unit and handset is same
frequency. Refer to Frequency Table (P.64).
4.2.1. TDD Frame Format
4.2.2. TDMA system
This system is the cycles of 10 ms, and has 6 duplex paths, but maximum duplex communication path is 5 because of dummy
bearer use.
In 1 slot 417 µs, the 10 ms of voice data is transmitted.
•2 - Handsets Link
Traffic Bearer
A link is established between base unit and handset.
The state where duplex communication is performed.
Handset doesn't make up duplex in no free RF channels because of interference. (*1)
Dummy Bearer
Base unit sends Dummy-data to the all stand-by state handsets.
Handsets receive that data for synchronization and monitoring request from the base unit.
Base unit doesn't send Dummy bearer in no free RF channels because of interference. (*1)
Note:
(*1) It is a feature under FCC 15 regulation and for interference avoidance.
In the case of checking RF parts, it is better in least interference condition.
417 µs (available) 417 µs (blind)
5 ms 5 ms
Up Link ( Handset ->Base Unit ) Down Link ( Base Unit ->Handset )
DATA rate : 1.152 Mbps
RX1 RX2 RX3 RX4 RX5 RX6 TX1 TX2 TX3 TX4 TX5 TX6
RX1 RX2 RX3 RX4 RX5 RX6 TX1 TX2 TX3 TX4 TX5 TX6
TX RX
RXTX
Traffic Bearer Dummy bearer
Base unit
Handset 1
(Stand by)
Handset 2
(Link)
Handset 3
(Link)

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
4.2.3. Signal Flowchart in the Radio Parts
Reception
Base unit:
A voice signal from TEL line is encoded to digital data and converted into a 1.9GHz modulated radio signal by BBIC(IC501).
The RF signal, after which is amplified in BBIC, is fed to selected antenna.
Handset:
As for a handset RF, RF signal is received in one antenna.
BBIC down-converts to 864 kHz IF signal from RX signal and demodulates it to digital data "RXDATA".
BBIC (IC1) converts RXDATA into a voice signal and outputs it to speaker.
Transmission
Handset:
A voice signal from microphone is encoded to digital data and converted into a 1.9GHz modulated radio signal by BBIC(IC1).
The RF signal, after which is amplified in BBIC, is fed to an antenna.
Base unit:
As for a base unit RF, RF signal is received in two antennas.
BBIC (IC501) compares RF signal levels and selects the antenna to be used. Then BBIC down-converts to 864 kHz IF signal
from RX signal in the selected antenna, and demodulates it to digital data "RXDATA".
BBIC (IC501) converts RXDATA into a voice signal and outputs it to TEL line.

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KX-TG7741S/KX-TG7742S/KX-TG7743S/KX-TGA470S
4.3. Block Diagram (Base Unit_Main)
KX-TG7741/7742/7743 BLOCK DIAGRAM (Base Unit_Main)
SIDE_TONE CIRCUIT
Crystal 10.368MHz
TR_RLY
TIP
RING
TEL_JACK
VRF
/
VPA
RF_Block
IC501 BBIC
DC5.5V+ GND
DC_JACK
+
-
CHARGE
3
4
2
1
D1
0
1
CHARGE DETECT
Q
7
0
1
Q141
Q161
REGULATOR
I
C30
2
KEY PAD
LED
VBAT
IC611
LCD
IC502
IC751
IC601
IC721 BT Module
Q301
+1.8V
AVD/VDD
RF_VDD
Q302
+2.4V
VDD_PA