Panasonic KX-TG3721BXB Service Manual
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Panasonic KX-TG3721BXB Service Manual

2.4 ghz digital cordless answering system
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Caller ID Compatible
KX-TGA371BXB/BXN
(Portable)
(Charger Unit)
Configuration for each model
Model No
Base Unit
Handset
KX-TG3721 1 (TG3721) 1 (TGA371)
KX-TG3722 1 (TG3721) 2 (TGA371)
1 (TGA371)
KX-TGA371*
*KX-TGA371 is also an optional accessory, which contains a
handset and a charger.
KX-TG3721BXB/BXN
(Base Unit)
Charger Unit
1
1
Telephone Equipment
KX-TG3721BXB
Model No.
KX-TG3721BXN
KX-TG3722BXB
KX-TG3722BXN
KX-TGA371BXB
KX-TGA371BXN
2.4 GHz Digital Cordless Answering
System
B: Black Version
N: Platinum Silver Version
(for Asia, Middle Near East and Other areas)
© Panasonic System Networks Co., Ltd. 2011
Unauthorized copying and distribution is a violation
of law.
ORDER NO. KM41108487CE

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Summary of Contents for Panasonic KX-TG3721BXB

  • Page 1 KX-TG3721 1 (TG3721) 1 (TGA371) KX-TG3722 1 (TG3721) 2 (TGA371) 1 (TGA371) KX-TGA371* *KX-TGA371 is also an optional accessory, which contains a handset and a charger. © Panasonic System Networks Co., Ltd. 2011 Unauthorized copying and distribution is a violation of law.
  • Page 2 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 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.

  • Page 3: Table Of Contents

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX TABLE OF CONTENTS PAGE PAGE 1 Safety Precautions----------------------------------------------- 4 15 Printed Circuit Board ------------------------------------------ 81 1.1. For Service Technicians --------------------------------- 4 15.1. Circuit Board (Base Unit_Main) ---------------------- 81 2 Warning -------------------------------------------------------------- 4 15.2. Circuit Board (Base Unit_Operation)---------------- 83 2.1. Battery Caution--------------------------------------------- 4 15.3.

  • Page 4: Safety Precautions

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 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.

  • Page 5: Discarding Of P. C. Board

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 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.

  • Page 6: Specifications

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 3 Specifications Handset Base Unit Charger Power Supply AC Adaptor Rechargeable Ni-MH battery AC Adaptor (PNLV226BX0Z, 100-240 V AC, (2 x 1.2 V, 550 mAh) (PNLV226BX0Z, 100-240 V AC, 50/60 Hz) 50/60 Hz) Receiving/Transmitting Frequency 91 channels within 2.4 GHz - 2.48 GHz 91 channels within 2.4 GHz - 2.48 GHz Receiving Method Super Heterodyne...

  • Page 7: Technical Descriptions

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4 Technical Descriptions 4.1. FHSS Description 4.1.1. Frequency The frequency range of 2.4 GHz-2.48 GHz is used. Transmitting and receiving channel between base unit and handset is same frequency. 4.1.2. FHSS (Frequency Hopping Spread Spectrum) This telephone is using an IC chip which has similar specification to WDCT (World Digital Cordless Telephone) and is the telephone system that can use multiple portable unit simultaneously.
  • Page 8 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.1.2.1. TDD Frame Format 5 ms 5 ms Up Link ( Handset - > Base Unit ) Down Link ( Base Unit - > Handset ) DATA rate : 576 Mbps 833 µs 4.1.2.2. 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.

  • Page 9: Block Diagram (Base Unit_Main)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.2. Block Diagram (Base Unit_Main)

  • Page 10: Tel Interface Circuit

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.3. Tel Interface Circuit...

  • Page 11: Block Diagram (Base Unit_Rf Part)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.4. Block Diagram (Base Unit_RF Part) ANT1 D801 ANT2 IC501 KX-TG3721/3722 BLOCK DIAGRAM (Base Unit_RF Part)

  • Page 12: Circuit Operation (Base Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5. Circuit Operation (Base Unit) General Description: (BBIC Flash Memory, EEPROM) is a digital speech/signal processing system that implements all the functions of speech compression, record and playback, and memory management required in a digital telephone answering machine. The BBIC system is fully controlled by a host processor. The host processor provides activation and control of all that functions as follows.
  • Page 13 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5.5. Power Supply Circuit/Reset Circuit The power supply voltage from AC adaptor is converted to VBAT (3.0V) in IC302. And +3.0V for peripherals and analog part is insulated from VBAT by Doubler of BBIC. Circuit Operation: VDD4 +5.5V +3.0V VDD3 IC502 IC501...
  • Page 14 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5.5.1. Charge Circuit The voltage from the AC adaptor is supplied to the charge circuits. +5.5V F301 R373 CHARGE+ C351 CHARGE-...
  • Page 15 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5.6. Telephone Line Interface Telephone Line Interface Circuit: Function • Bell signal detection • ON/OFF hook and pulse dial circuit • Side tone circuit Bell (RINGING) signal detection and OFF HOOK circuit: In the idle mode, Q141 is open to cut the DC loop current and decrease the ring load. When ring voltage appears at the Tip (T) and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows: L1T→L101→C105→R105→R110→R111→R112→BBIC pin18(RINGING) When the CPU (BBIC) detects a ring signal, Q141 turns on, thus providing an off-hook condition (active DC current flow through...
  • Page 16 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5.7. Parallel Connection Detect Circuit/Auto Disconnect Circuit Function: In order to disable call waiting and stutter tone functions when using telephones connected in parallel, it is necessary to have a circuit that judges whether a telephone connected in parallel is in use or not. This circuit determines whether the telephone connected in parallel is on hook or off hook by detecting changes in the T/R voltage.
  • Page 17 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.5.8. Calling Line Identification (Caller ID)/Call Waiting Caller ID Function: The caller ID is a chargeable ID which the user of a telephone circuit obtains by entering a contract with the telephone company to utilize a caller ID service. For this reason, the operation of this circuit assumes that a caller ID service contract has been entered for the circuit being used.

  • Page 18: Block Diagram (Handset)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.6. Block Diagram (Handset)

  • Page 19: Block Diagram (Handset_Rf Part)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.7. Block Diagram (Handset_RF Part) TXON KX-TGA371 BLOCK DIAGRAM (Handset_RF Part)

  • Page 20: Circuit Operation (Handset)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.8. Circuit Operation (Handset) 4.8.1. Outline Handset consists of the following ICs as shown in Block Diagram (Handset) (P.18). • DECT BBIC (Base Band IC): IC1 - All data signals (forming/analyzing ACK or CMD signal) - All interfaces (ex: Key, Detector Circuit, Charge, EEPROM, LCD) •...
  • Page 21 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.8.3. Charge Circuit Circuit Operation: When charging the handset on the Base Unit, the charge current is as follows; DCP+(5.5 V) → F301 → R371 → R372 → D362 → CHARGE+(Base) → CHARGE+(Handset) → → Q4 → F1 → BATTERY+...

  • Page 22: Behavior Of Electric Power Failure

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.9. Behavior of Electric Power Failure In case that the power from AC adaptor is lost and lose radio waves, BBIC (IC1) turns Q11 and Q10 ON since handset presumes that base unit's power is failed. Base unit detects that power voltage of AC adaptor +5.5V is OFF at IC351, then turns Q351 ON. It's possible to use the units during the power failure, supplying power to VBAT of base unit from battery of handset through IC6, CHG terminal and Q351.

  • Page 23: Signal Route

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 4.11. Signal Route ROUTE SIGNAL ROUTE HANDSET TX HANDSET MIC - C11/13 - RA4 - IC1(19/20) - <HANDSET_RF_TX_ROUTE> - ANT. --- ANT. - <BASE_UNIT_RF_RX_ROUTE> - IC501(2/3 - 27) - C184 - Q161 -Q141 - D101 - L101/[L102-P101] - T/R (TEL LINE) HANDSET RX T/R (TEL LINE) - L101/[P101-L102] - D101 - Q141 - R165 - C173 - R178 - IC501(25 - 94/95) - <BASE_UNIT_RF_TX_ROUTE>...
  • Page 24 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX SIGNAL ROUTE ROUTE GREETING HANDSET MIC - C11/13 - RA4 - IC1(19/20) RECORDING - <HANDSET_RF_TX_ROUTE> - ANT. --- ANT - <BASE_UNIT_RF_RX_ROUTE> - IC501(2/3 - 69/70) - IC601 IC601 - IC501(69/70 - 27) - C184 - Q161 -Q141- D101 - L101/[L102-P101] - T/R (TEL LINE) GREETING PLAY TO TEL LINE T/R (TEL LINE) - L101/[P101-L102] - D101 - Q141 - R165 - C173 - R178...

  • Page 25: Location Of Controls And Components

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 5 Location of Controls and Components Refer to the Operating Instructions. Note: You can download and refer to the Operating Instructions (Instruction book) on TSN Server. 6 Installation Instructions Refer to the Operating Instructions. Note: You can download and refer to the Operating Instructions (Instruction book) on TSN Server. 7 Operating Instructions Refer to the Operating Instructions.

  • Page 26: Test Mode

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 8 Test Mode 8.1. Engineering Mode 8.1.1. Base Unit Important: Make sure the address on LCD is correct when entering new data. Otherwise, you may ruin the unit. soft keys {OFF} Navigator key ? (Volume) key {FLASH} {CALL WAIT} Dial keypad H/S LCD H/S key operation...
  • Page 27 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Set Addr.: 7). Press , a long confirmation beep New Data will be heard. CLEAR 8). Press {OFF} to return to standby mode. Set Addr.: After that, turn the base unit power off and then power on. _ _ _ _ BACK or {>} at "...
  • Page 28 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 8.1.2. Handset Important: Make sure the address on LCD is correct when entering new data. Otherwise, you may ruin the unit. soft keys {OFF} Navigator key ? (Volume) key {FLASH} {CALL WAIT} Dial keypad H/S key operation H/S LCD 1).
  • Page 29 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Frequently Used Items (Handset) ex.) Items Address Default Data New Data Possible Adjusted Possible Adjusted Remarks Value MAX (hex) Value MIN (hex) Battery Low 00 09 (*2) Frequency 00 07/00 08 70/02 00 02~00 06 Given value Note: (*1) When you enter the address or New Data, please refer to the table below. Desired Number (hex.) Input Keys Desired Number (hex.)

  • Page 30: Copying Phonebook Items When Repairing

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 8.2. Copying Phonebook Items when Repairing You can copy the handset phonebook to another (compatible Panasonic) handset. This will help to save the original phonebook data which the customer has registered. Refer to the following procedures. Phonebook data is stored in a handset.
  • Page 31 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Case 3: A handset has a defect. (Radio transmission is functioning.) Service center has a normal HS (B). HS (A) HS (A) HS (B) BS (A) BS (A) 1. Cancel HS (A). 2. Register HS (B) as a handset no. 1. 3.

  • Page 32: Service Mode

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 9 Service Mode 9.1. How to Clear User Setting Units are reset to the Factory settings by this operation (Erase recorded Voice messages, stored Phone numbers, Caller list and etc.) Note: • Some menus are not reset. Refer to Operating Instructions (P.25). •...

  • Page 33: Troubleshooting Guide

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10 Troubleshooting Guide 10.1. Troubleshooting Flowchart FLOW CHART Not working Power ON Base Unit Check Power Not record Record Check Record Not playback Playback Pre-Message Check Playback Link No link No charge Battery Charge Check Battery Charge Check Link Range Check the RF part No voice...
  • Page 34 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.1. Check Power 10.1.1.1. Base Unit Is the AC Adaptor inserted into AC outlet? (*1) AC Adaptor. Is output voltage of AC adaptor 5.5 V? Check Check Power Supply Circuit. Check VDD1(1.8V) :Test point (VDD1) RSTN: Reset = "High"? Check Reset Circuit.
  • Page 35 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.2. Check Record 10.1.2.1. Base Unit Not record Incoming Message Check Telephone Line Interface Check Bell signal. [Bell]. Check Telephone Line Interface Does the unit catch line? [OFF HOOK]. Check Line In: Pin 25 of BBIC. Check ICM Recording in Signal Route. Check Auto Disconnect Circuit.
  • Page 36 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.3. Check Playback 10.1.3.1. Base Unit Check VDD1(1.8V) :Test point (VDD1) Check Power Supply Circuit. Check output of BBIC (Pin 41,43). Check BBIC and Flash Memory. Check Speaker and its surroundings. Cross Reference: Note: Power Supply Circuit/Reset Circuit (P.13) Flash Memory is IC601.
  • Page 37 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.4.3. Charger Unit Plug in the AC Power source. Charge Handset on Charger Unit. Check Charge Circuit of Charger Unit. Is the voltage of two charge contacts about 3 V or more? Check Handset. Check Charge Contacts at Charger Unit from mechanical point of view.
  • Page 38 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.5. Check Link 10.1.5.1. Base Unit Does Base Unit make link with normal working Base Unit is OK. Check Handset. Handset? Is the voltage of VDD3 about 3.0V? Check around Power Supply Circuit. Is the voltage of VDD1 about 1.8V? Does the RF clock (CLK) oscillate at 10.368 MHz in Check around X501 and RF module and adjust Base Unit Test Mode?
  • Page 39 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.5.2. Handset Does Handset make link with Base Unit? Handset is OK. Check Base Unit. (Correct working unit) Is the voltage of TP BAT about 2.2~2.8 V? Check the batteries. Check around Power Supply Circuit/Reset Circuit. Is the voltage of TP 1.8V about 1.8 V? Is the voltage of TP CP3.0 about 3.0 V? Adjust +3.0V Vottage to 3.0V Does the RF clock (CLK) oscillate: 10.368 MHz...
  • Page 40 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.6. Check the RF part 10.1.6.1. Finding out the Defective part 1. Prepare Regular HS(*1) and Regular BU(*2). 2. a. Re-register regular HS (Normal mode) to base unit (to be checked). If this operation fails in some ways, the base unit is defective. b.
  • Page 41 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.6.2. RF Check Flowchart Please refer to the each item. Start Link Control Check BBIC interface parts. confirmation signal (RF Block <->BBIC on BU/HS P.C.B) Normal confirmation X'tal Frequency Adjust X'tal Frequency. (*1) confirmation TX confirmation Check TX Block. Range confirmation TEST RANGE Check.
  • Page 42 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.7. Registering a Handset to the Base Unit 1 Handset: {MENU} i # 1 3 0 2 Base unit: Press and hold {LOCATOR} for about 5 seconds until the registration tone sounds. If all registered handsets start ringing, press {LOCATOR} again to stop, then repeat this step.
  • Page 43 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 10.1.10. Check Handset Transmission Check MIC of handset. Check handset Tx in Signal Route. Cross Reference: Signal Route (P.23) 10.1.11. Check Handset Reception Check speaker of handset. Check handset Rx in Signal Route. Cross Reference: Signal Route (P.23) Note: When checking the RF part, Refer to Check the RF part (P.40).

  • Page 44: Disassembly And Assembly Instructions

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 11 Disassembly and Assembly Instructions 11.1. Disassembly Instructions 11.1.1. Base Unit Remove the 4 screws to remove the cabinet cover. Remove the tape and solders. Cabinet cover Tape and solders Remove the screw to remove the jack holder. Jack holder...
  • Page 45 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Remove the parallel wire and screw to remove the main P.C. board. Remove the 2 screws to remove the operational P.C. board.
  • Page 46 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 11.1.2. Handset 2 screws Remove the 2 screws. Insert a plastic card. (Ex. Used SIM card etc.) Cabinet body between the cabinet body and the cabinet cover, then pull it along the gap to open the cabinet. Cabinet cover Likewise, open the other side of the cabinet.
  • Page 47 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 11.1.3. Charger Unit 2 charge terminals...

  • Page 48: How To Replace The Base Unit Lcd

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 11.2. How to Replace the Base unit LCD Fit the heatseal of a new LCD. Vertical Interval Tolerance 0.2mm Horizontal Interval Tolerance 0.2mm If interval tolerance between center lines is less than 0.2 mm, it is o.k. New LCD Operational P.C.B.
  • Page 49 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Attach the LCD and fix by hook A (two points).

  • Page 50: How To Replace The Handset Lcd

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 11.3. How to Replace the Handset LCD Note: The illustrations are simplified in this page. They may differ from the actual product. P. C. board Vertical Interval Tolerance Peel off the FFC (Flexible Flat Cable) from 0.2 mm the LCD, in the direction of the arrow. Take care to ensure that the foil on the P.C.

  • Page 51: Measurements And Adjustments

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12 Measurements and Adjustments This chapter explains the measuring equipment, the JIG connection, and the PC setting method necessary for the measurement in Troubleshooting Guide (P.33) 12.1. Equipment Required • Digital multi-meter (DMM): it must be able to measure voltage and current. •...
  • Page 52 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.2.2. Connections (Handset) Connect the DC Power or Battery to BATT+ and BATT-. Connect the JIG cable GND (black) to GND. Connect the JIG cable UTX (yellow) to UTX and URX (red) to URX. URX (red) To Serial Port UTX (yellow) (com port 1*) GND (black)
  • Page 53 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.2.3. How to install Batch file into P.C. Insert the Batch file CD-ROM into CD-ROM drive and copy PNZZTG**** folder to your PC (example: D drive). <Example for Windows> On your computer, click [Start], select Programs Open an MS-DOS mode window. (All Programs for Windows XP/Windows Server 2003), then click MS-DOS Prompt.
  • Page 54 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.2.4. Commands See the table below for frequently used commands. Command name Function Example rdeeprom Read the data of EEPROM Type “rdeeprom 00 00 FF”, and the data from address “00 00” to “FF” is read out. readid Read ID (RFPI) Type “readid”, and the registered ID is read out.

  • Page 55: Adjustment Of Base Unit

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.3. Adjustment of Base Unit When IC501 (BBIC) or IC611 (EEPROM) is exchanged, the Bandgap adjustment and the Frequency adjustment are necessary. When X501 (X'tal) is exchanged, the Frequency adjustment is necessary. Procedure: 1. Open a window of MS-DOS mode from the start-up menu. 2.

  • Page 56: Adjustment Of Handset

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.4. Adjustment of Handset When IC5(BBIC) or IC3 (EEPROM) is exchanged, the Bandgap adjustment and the Frequency adjustment are necessary. When X1 (X'tal) is exchanged, the Frequency adjustment is necessary. Procedure: 1. Open a window of MS-DOS mode from the start-up menu. 2.
  • Page 57 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Adjustment of backup power supply: Supply a handset with 2.6V power, then connect serial JIG cables. The power should be DC 2.6V 0.02V between BAT and GND. Run the batch file "DAVchk_TGA371_381.bat", which is found in the CD-ROM. Read and confirm the display data. If successful, "OK" is displayed as below. Press any key, and verify backup power supply.
  • Page 58 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Verifying backup power supply: Run the batch file "DAVread_only_TGA371_381.bat", which is found in the CD-ROM. As shown in the picture below, the readout of four times detection are displayed. The average should be within the range of 00 to 06 hex. Press any key to continue.

  • Page 59: Adjustment Standard (Base Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.5. Adjustment Standard (Base Unit) When connecting the simulator equipment for checking, please refer to below. 12.5.1. Bottom View Spectrum Analyzer ANT2_TP ANT1_TP D301 5.5V C301 VDD3 R363 R321 R362 R364 C343 3.0A R361 F301 C321 Q363 STM/CKM/P15 R365 JTAG Q362 Q361...

  • Page 60: Adjustment Standard (Charger Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.6. Adjustment Standard (Charger Unit) When connecting the simulator equipment for checking, please refer to below. 12.6.1. Bottom View Digital Volt Meter /2 W 3.0A DC POWER DC 5.5 V...

  • Page 61: Adjustment Standard (Handset)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.7. Adjustment Standard (Handset) When connecting the simulator equipment for checking, please refer to below. 12.7.1. Component View ANT-SHORT ANT-SHORT-GND PNLB1168Z KX-TGA371 KX-TGA32CN ANT1_TP C850 C838 C812 C837 L826 C822 C814 C827 C810 R807 C820 C805 L803 L863 JTAG C866 C806 L864...

  • Page 62: Things To Do After Replacing Ic Or X'tal

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.8. Things to Do after Replacing IC or X'tal If repairing or replacing EEPROM or X'tal, it is necessary to download the required data such as Programming data or adjustment data, etc. in memory. The set doesn't operate if it is not executed. 12.8.1.
  • Page 63 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.8.1.2. Handset First, operate the PC setting according to The Setting Method of JIG (P.51). Then download the appropriate data according to the following procedures. Items How to download/Required adjustment FLASH (IC4) Program D/L 1) Make sure to connect the JIG cable, then disconnect the DC Power in order to download the data.

  • Page 64: How To Check The Handset Receiver

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.9. How to Check the Handset 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. SPEAKER: Is the value between (+) terminal and (–) terminal about 8 ? RECEIVER: Is the value between (+) terminal and (–) terminal about 34 ?

  • Page 65: Frequency Table (Mhz)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 12.10. Frequency Table (MHz) Channel Center Frequency (MHz) RX Local Frequency (MHz) 65 (41H) 2457.216 2458.08 Channel Center Frequency (MHz) RX Local Frequency (MHz) 66 (42H) 2458.08 2458.944 2 (02H) 2402.784 2403.648 67 (43H) 2458.944 2459.808 3 (03H) 2403.648 2404.512 68 (44H) 2459.808...

  • Page 66: Miscellaneous

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13 Miscellaneous 13.1. How to Replace the LLP (Leadless Leadframe Package) IC Note: This description is only applied on the model with Shield case. 13.1.1. Preparation • PbF (: Pb free) Solder • Soldering Iron Tip Temperature of 700 °F ± 20 °F (370 °C ± 10 °C) Note: We recommend a 30 to 40 Watt soldering iron.
  • Page 67 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.1.4. How to Install the IC 1. Place the solder a little on the land where the radiation GND pad on IC bottom is to be attached. Soldering Iron Land Solder P.C.Board 2. Place the solder a little on the land where IC pins are to be attached, then place the IC. Note: •...

  • Page 68: How To Replace The Flat Package

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.2. How to Replace the Flat Package IC Even if you do not have the special tools (for example, a spot heater) to remove the Flat IC, with some solder (large amount), a soldering iron and a cutter knife, you can easily remove the ICs that have more than 100 pins. 13.2.1.
  • Page 69 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.2.3. How to Install the IC 1. Temporarily fix the FLAT PACKAGE IC, soldering the two marked pins. *Check the accuracy of the IC setting with the corresponding soldering foil. 2. Apply flux to all pins of the FLAT PACKAGE IC. 3.

  • Page 70: How To Replace The Shield Case

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.3. How to Replace the Shield Case 13.3.1. Preparation • PbF (: Pb free) Solder • Soldering Iron Tip Temperature of 700°F ± 20°F (370°C ± 10°C) Note: We recommend a 30 to 40 Watt soldering iron. An expert may be able to use a 60 to 80 Watt iron where someone with less experience could overheat and damage the PCB foil.
  • Page 71 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.3.4. How to Install the Shield Case Note: • If you don’t have special tools (ex. Hot air disordering tool), conduct the following operations. • Shield case’s No. : PNMC1032Z, PNMC1033Z 1. Put the shield case. 2. Solder the surroundings.

  • Page 72: Terminal Guide Of The Ics, Transistors And Diodes

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 13.4. Terminal Guide of the ICs, Transistors and Diodes 13.4.1. Base Unit (Reverse View) C3FBLY000125 C3FBLY000124 C0EBE0000124 C0DBEYY00102 B1ACGP000008 PNWIG3411BXH C1CB00003545 B1ABDM000001, B1ADGE000012 B1ADNB000003, B1ABDF000017 B1GBCFYY0010, B1GBCFYY0020 DSC7003S0L PSVTUMG11NTR PQVDMD5S Cathode Cathode Cathode Anode Anode Anode B0ECKM000008 1SS355 PQVDPTZT2530 B0DCCD000013 LNJ237W82RA 13.4.2.

  • Page 73: Schematic Diagram

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14 Schematic Diagram 14.1. For Schematic Diagram 14.1.1. Base Unit (Schematic Diagram (Base Unit_Main)) Notes: 1. DC voltage measurements are taken with voltmeter from the negative voltage line. Important Safety Notice: Components identified by mark have special characteristics important for safety.

  • Page 74: Schematic Diagram (Base Unit_Main)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14.2. Schematic Diagram (Base Unit_Main) WBX02 10pin PARALLEL WIRE +3.0_CP2 +3.0_CP2 Q653 LCD_BLTR LCD_BLTL LCD_BLT1 L661 LCD_GND LCD_RST LCD_RST L665 LCD_CS LCD_CS L664 LCD_CD LCD_CD L662 SPI2_DO LCD_SID L663 SPI2_CLK +1.8V LCD_SCL C473 10p LCD_VDD LCD_BLT2 C472 10p C506 +3.0V 2.2u +3.0_CP2...
  • Page 75 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX REFERENCE *Q141 *R160 1XX : TEL LINE 3XX : POWER, CHARGE 4XX : MIC, SP Q161 5XX : BBIC R141 6XX : FLASH, EEPROM, KEY, LCD 7XX : FOR DK/BT 100k 8XX : RF C165 NC C163 NC *R169 C173 R164 R161...

  • Page 76: Schematic Diagram (Base Unit_Rf)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14.3. Schematic Diagram (Base Unit_RF) ANT_2 ANT_1 ANT1_TP ANT2_TP L=17mm *D803 C851 C859 C853 W 0.15mm W 0.15mm L 22+/-4mm L 22+/-4mm 1st or 4th layer 1st or 4th layer W 0.15mm L 20+/-2mm 3rd layer R807 TXON *D802 C826 L804 4.7n...

  • Page 77: Schematic Diagram (Base Unit_Operation)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14.4. Schematic Diagram (Base Unit_Operation) @CBN12-0.9-2.8X14. CN901 R901 LED905 KEY_1 R902 LED906 C901 /RSTB LCD_GND /CSB LCD_RST LCD_CS LCD_CD SCLK LCD_SID VDD1 LCD_SCL VDD2 C902 LCD_VDD R903 LED907 R904 LED908 ERASE KEYS_E MSG4 KEYS_C MSG3 KEYIN2 KEYS_D MSG2 KEYIN3 MSG1 SKIP KEYIN1...

  • Page 78: Schematic Diagram (Handset_Main)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14.5. Schematic Diagram (Handset_Main) Charge Current BATTERY R1 NC BATT+ 2.5A To Battery BATT- POWER K1000p 220k R9 30k CHG+ +1.8V 3.3(3216) 1.2k CHARGE Terminal CHG- 61 P0_0/UTX +1.8V K0.1u 62 RSTn R3 1k 63 JTAG LCD_CSB 64 P2_5/PCM_FSC/SF 65 P2_4/SCL1/PCM_DO/DP3 66 P2_3/SDA1/PCM_DI/DP2 LCD_RESET...
  • Page 79 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX (MAX500mA) +1.8V 1.8V W 0.15mm L 20+/-2mm RF BLOCK ANT-Short 3rd layer R807 ANT-Short-GND TXON RF_RX ANT1_TP *D801 C826 L826 RF_RXn 4.7n L863 1.5n L864 1.5n RF_RXp L=17mm W 0.125mm 3.0V L 7.6mm 3.0V Gap 0.125mm CP_V2 CP+3.0V BATTERY 1st layer CP_V2 CP3.0V...

  • Page 80: Schematic Diagram (Charger Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 14.6. Schematic Diagram (Charger Unit) 6.8 (2W) SCHEMATIC DIAGRAM (Charger Unit)

  • Page 81: Printed Circuit Board

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15 Printed Circuit Board 15.1. Circuit Board (Base Unit_Main) 15.1.1. Component View C851 C859 D803 ANT_1 C341 ANT_2 C857 C858 R891 SA101 C342 C855 P101 C861 C856 C306 C345 SA103 D101 C828 D801 C823 C812 R132 D142 C811 C822 R133 L803 C810...
  • Page 82 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15.1.2. Bottom View ANT2 ANT2_TP ANT1_TP D301 C301 VDD3 R363 R321 R362 C343 R364 3.0A R361 F301 C321 Q363 STM/CKM/P15 R365 JTAG Q362 Q361 C602 PNLB1165Z Q601 IC611 KX-TG372xH R606 TG33CNH C603 RSTN R611 R312 R104 R612 C809 R613 R106 Q302 IC601...

  • Page 83: Circuit Board (Base Unit_Operation)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15.2. Circuit Board (Base Unit_Operation) R903 R901 LED905 LED907 R904 R902 LED908 LED906 C902 C901 ERASE TG413xUS MSG1 MSG1 TG662xEU LED902 SKIP TG372xBX TG33CN MSG3 MSG4 STOP LOCAT/INT DOWN PNLB1911Z KX-TG3721/3722 CIRCUIT BOARD (Base Unit_Operation (Component View))
  • Page 84 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Memo...

  • Page 85: Circuit Board (Handset_Main)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15.3. Circuit Board (Handset_Main) 15.3.1. Component View ANT-SHORT ANT-SHORT-GND PNLB1168Z KX-TGA371 KX-TGA32CN ANT1_TP ANT1_TP ANT_GND C850 C838 C812 C837 C822 L826 C814 C827 C810 R807 C820 C805 L803 L863 JTAG C866 C806 L864 R203 C701 C702 R215 VDD 1.8V C189 1.8V C190...
  • Page 86 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15.3.2. Bottom View C106 C580 C103 SOFT_A SOFT_B SOFT_C TALK LED8 LED6 LEFT RIGHT DOWN CARBON_CL1 KX-TGA371 CIRCUIT BOARD (Handset_Main (Bottom View))

  • Page 87: Circuit Board (Charger Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 15.4. Circuit Board (Charger Unit) 15.4.1. Component View CIRCUIT BOARD (Charger Unit (Component View)) 15.4.2. Bottom View 3.0A CIRCUIT BOARD (Charger Unit (Bottom View))

  • Page 88: Exploded View And Replacement Parts List

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 16 Exploded View and Replacement Parts List 16.1. Cabinet and Electrical Parts (Base Unit) 19 (*1) (CUSHION/LCD) Push the lead wire toward the arrow after it puts a seal. (*1) PCB1 Do not process a lead wire on jack holder. PCB2 Ref.No.

  • Page 89: Cabinet And Electrical Parts (Handset)

    (*1) This cable is fixed by welding. Refer to How to Replace the Handset LCD (P.50). (*2) The rechargeable Ni-MH battery HHR-4MRT is available through sales route of Panasonic. (*3) Attach the SPACER (No. 115) to the exact location described above.

  • Page 90: Cabinet And Electrical Parts (Charger Unit)

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 16.3. Cabinet and Electrical Parts (Charger Unit) 200-1 PCB200 200-2 200-3 200-4...

  • Page 91: Accessories

    KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 16.4. Accessories...

  • Page 92: Replacement Parts List

    1. RTL (Retention Time Limited) PQHR11313Z GUIDE, SPEAKER ABS-HB Note: PNKE1090Z1 CASE, CHARGE TERMINAL PS-HB (for KX-TG3721BXB)(for The “RTL” marking indicates that its Retention Time is KX-TG3722BXB) Limited. PNKE1090Z3 CASE, CHARGE TERMINAL PS-HB When production is discontinued, this item will...
  • Page 93 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX Safety Ref. Part No. Part Name & Description Remarks Safety Ref. Part No. Part Name & Description Remarks Q363 B1ABDF000017 TRANSISTOR(SI) R354 ERJ2GEJ103 Q601 B1ABDF000017 TRANSISTOR(SI) R355 ERJ2GEJ681 Q653 PSVTUMG11NTR TRANSISTOR(SI) R358 ERJ2GEJ103 (DIODES) R359 ERJ2GEJ103 D101 PQVDMD5S DIODE(SI) R360 ERJ2GEJ563 D133...
  • Page 94 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 16.5.1.3. Operational P.C.Board parts Safety Ref. Part No. Part Name & Description Remarks C312 ECUV1C105KBV 1 C321 ECUV1A105KBV 1 Safety Ref. Part No. Part Name & Description Remarks C341 EEE0JA221WP C342 ECUE1A104KBQ 0.1 PCB2 PNWP23721BXH OPERATIONAL P.C.BOARD ASS'Y (RTL) C343 ECUE1H100DCQ 10p (LEDS)
  • Page 95 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX (*3) When removing E106, use special tools (ex. Hot air Safety Ref. Part No. Part Name & Description Remarks disordering tool). ERJ2GEJ100 ERJ2GEJ102 ERJ2GEJ821 Safety Ref. Part No. Part Name & Description Remarks ERJ2GEJ821 PCB100 PNWPGA371BXR MAIN P.C.BOARD ASS'Y ERJ2GEJ152 1.5k (RTL)
  • Page 96 KX-TG3721BX/KX-TG3722BX/KX-TGA371BX 16.5.3.2. Main P.C. Board Parts Safety Ref. Part No. Part Name & Description Remarks C344 ECUE1A104KBQ 0.1 C345 ECUE1H100DCQ 10p Safety Ref. Part No. Part Name & Description Remarks C580 ECUE1H100DCQ 10p C701 ECUV1A105KBV 1 PCB200 PNWPTGA660CH MAIN P.C.BOARD ASS'Y (RTL) C702 ECUE1H100DCQ 10p...

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