Panasonic KX-TG8421HGN Service Manual
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Panasonic KX-TG8421HGN Service Manual

Panasonic KX-TG8421HGN Service Manual

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Telephone Equipment
KX-TG8421HGN
Model No.
KX-TGA840FXN
Digital Cordless Answering System
N:Platinum Silver Version
(for Hungary)
© Panasonic Communications Co., Ltd. 2009.
Unauthorized copying and distribution is a violation
of law.
ORDER NO. KM40904907CE

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Summary of Contents for Panasonic KX-TG8421HGN

  • Page 1 ORDER NO. KM40904907CE Telephone Equipment KX-TG8421HGN Model No. KX-TGA840FXN Digital Cordless Answering System N:Platinum Silver Version (for Hungary) © Panasonic Communications Co., Ltd. 2009. Unauthorized copying and distribution is a violation of law.
  • Page 2 KX-TG8421HGN/KX-TGA840FXN...

  • Page 3: Table Of Contents

    KX-TG8421HGN/KX-TGA840FXN TABLE OF CONTENTS PAGE PAGE 1 Safety Precautions----------------------------------------------- 4 12.5. Terminal Guide of the ICs, Transistors and 1.1. For Service Technicians --------------------------------- 4 Diodes ------------------------------------------------------ 80 2 Warning -------------------------------------------------------------- 4 13 Schematic Diagram -------------------------------------------- 81 2.1. Battery Caution--------------------------------------------- 4 13.1.

  • Page 4: Safety Precautions

    KX-TG8421HGN/KX-TGA840FXN 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 pre- vent fires, injury or electric shock, which can be caused by improper repair work.

  • Page 5: Discarding Of P.c. Board

    KX-TG8421HGN/KX-TGA840FXN 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-TG8421HGN/KX-TGA840FXN 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...

  • Page 7: Technical Descriptions

    KX-TG8421HGN/KX-TGA840FXN 4 Technical Descriptions 4.1. Block Diagram (Base Unit)

  • Page 8: Circuit Operation (Base Unit)

    KX-TG8421HGN/KX-TGA840FXN 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...

  • Page 9: Power Supply Circuit

    KX-TG8421HGN/KX-TGA840FXN 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): DC Jack (+6.5 V) →D1→ IC1 → IC7 DC Jack (+6.5 V) →D1→...
  • Page 10 KX-TG8421HGN/KX-TGA840FXN 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.

  • Page 11: Block Diagram (Handset)

    KX-TG8421HGN/KX-TGA840FXN 4.3. Block Diagram (Handset)

  • Page 12: Circuit Operation (Handset)

    KX-TG8421HGN/KX-TGA840FXN 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 Power Amp.)

  • Page 13: Circuit Operation (Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 4.5. Circuit Operation (Charger Unit) 4.5.1. Power Supply Circuit The power supply is as shown.

  • Page 14: Signal Route

    KX-TG8421HGN/KX-TGA840FXN 4.6. Signal Route...
  • Page 15 KX-TG8421HGN/KX-TGA840FXN...

  • Page 16: Location Of Controls And Components

    KX-TG8421HGN/KX-TGA840FXN 5 Location of Controls and 5.1.2. Handset Components 5.1. Controls 5.1.1. Base Unit...

  • Page 17: Installation Instructions

    KX-TG8421HGN/KX-TGA840FXN 6 Installation Instructions 6.2. Battery 6.2.1. Battery Installation 6.1. Connections See For Service Hint (P.28) 6.2.2. Battery Charge Note for service: The battery strength may not be indicated correctly if the battery is disconnected and connected again, even after it is fully charged.
  • Page 18 KX-TG8421HGN/KX-TGA840FXN 6.2.3. Battery Level 6.2.4. Panasonic Ni-MH Battery Performance (supplied batteries)

  • Page 19: Operating Instructions

    KX-TG8421HGN/KX-TGA840FXN 7 Operating Instructions 7.1. Programmable Settings You can customise the unit by programming the following features using the handset. 7.1.1. Programming by scrolling through the display menus...
  • Page 20 KX-TG8421HGN/KX-TGA840FXN *1 The item will not be reset when pressing keys. Refer to How to Clear User Setting (P.35). *2 The item will not be reset when pressing keys. Refer to How to Clear User Setting (P.35). Cross Reference: Registering a Handset to a Base Unit (P.22)

  • Page 21: Answering System Settings

    KX-TG8421HGN/KX-TGA840FXN 7.1.2. Answering System Settings 7.1.3. SMS Settings...

  • Page 22: Registering A Handset To A Base Unit

    KX-TG8421HGN/KX-TGA840FXN 7.2. Registering a Handset to a Base Unit If you forget your PIN, see For Service Hint (P.28) Note: • When you purchase an additional handset, refer to the additional handset's installation manual for registration. 7.2.1. Deregistering a Handset 7.2.2.

  • Page 23: Copying Phonebook Entries

    KX-TG8421HGN/KX-TGA840FXN 7.3. Copying Phonebook Entries You can copy phonebook entries to the phonebook of another compatible Panasonic handset. Note: • Category settings for phonebook entries are not copied. Copying all entries 7.3.1. 7.4. Dialling mode 7.5. Error Messages...

  • Page 24: Troubleshooting

    KX-TG8421HGN/KX-TGA840FXN 7.6. Troubleshooting...
  • Page 25 KX-TG8421HGN/KX-TGA840FXN Cross Rreference: For Service Hint (P.28)
  • Page 26 KX-TG8421HGN/KX-TGA840FXN...
  • Page 27 KX-TG8421HGN/KX-TGA840FXN...

  • Page 28: For Service Hint

    KX-TG8421HGN/KX-TGA840FXN 7.7. For Service Hint Cross Reference: Battery Charge (P.17)

  • Page 29: Service Mode

    KX-TG8421HGN/KX-TGA840FXN 8 Service Mode 8.1. Engineering Mode 8.1.1. Base Unit...
  • Page 30 KX-TG8421HGN/KX-TGA840FXN Frequently Used Items (Base Unit) ex.) Items Address Default Data New Data Remarks C-ID (FSK) sensitivity 04 B6 01 (6 dB up) 02 (12 dB up) When hex changes from “00” to “01” or “02”, gain increases by 6 dB or 12 dB.
  • Page 31 KX-TG8421HGN/KX-TGA840FXN 8.1.2. Handset...
  • Page 32 KX-TG8421HGN/KX-TGA840FXN Frequently Used Items (Handset) ex.) Items Address Default Data New Data Possible Adjusted Possible Adjusted Remarks Value MAX (hex) Value MIN (hex) Sending level 00 06 Adjusted value Given value (*2) Receiving level 00 07 Adjusted value Given value...

  • Page 33: Copying Phonebook Items When Repairing

    KX-TG8421HGN/KX-TGA840FXN 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. Available models: KX-TG8411/KX-TG8421 Refer to the following procedures.
  • Page 34 KX-TG8421HGN/KX-TGA840FXN Note: • BS=Base Unit , HS=Handset • If the max number of handsets are already registered to the base unit, a new handset cannot be registered. • To register the handset, refer to Registering a Handset to a Base Unit (P.22) •...

  • Page 35: How To Clear User Setting

    KX-TG8421HGN/KX-TGA840FXN 8.3. 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.19).

  • Page 36: Troubleshooting Guide

    KX-TG8421HGN/KX-TGA840FXN 9 Troubleshooting Guide 9.1. Troubleshooting Flowchart Flow Chart Cross Reference: Check Power (P.37) Bell Reception (P.47) Check Battery Charge (P.38) Check Link (P.39) Check the RF part (P.43) Check Handset Transmission (P.46) Check Handset Reception (P.46) Signal Route (P.14) Check Caller ID (P.46)

  • Page 37: Check Power

    KX-TG8421HGN/KX-TGA840FXN 9.1.1. Check Power 9.1.1.1. Base Unit Is the AC Adaptor inserted into AC outlet? (*1) Cross Reference: Note: Power Supply Circuit (P.9) (*1) Refer to Specifications (P.6) for part number and supply voltage of AC Adaptor. 9.1.1.2. Handset Cross Reference:...

  • Page 38: Charger Unit

    KX-TG8421HGN/KX-TGA840FXN 9.1.2. Check Battery Charge 9.1.2.1. Base Unit Cross Reference: Charge Circuit (P.12) 9.1.2.2. Handset Cross Reference: Check Power (P.37) Charge Circuit (P.12) 9.1.2.3. Charger Unit Cross Reference: Charge Circuit (P.12)

  • Page 39: Check Link

    KX-TG8421HGN/KX-TGA840FXN 9.1.3. Check Link 9.1.3.1. Base Unit Note: (*1) Refer to Troubleshooting by Symptom (Base Unit and Charger Unit) (P.48) Cross Reference: Check Point (Base Unit) (P.48) Power Supply Circuit (P.9)
  • Page 40 KX-TG8421HGN/KX-TGA840FXN Cross Reference: Check Point (Base Unit) (P.48)
  • Page 41 KX-TG8421HGN/KX-TGA840FXN 9.1.3.2. Handset Cross Reference: Check Point (Handset) (P.52) Power Supply Circuit/Reset Circuit (P.12)
  • Page 42 KX-TG8421HGN/KX-TGA840FXN Cross Reference: Check Point (Handset) (P.52)

  • Page 43: Check The Rf Part

    KX-TG8421HGN/KX-TGA840FXN 9.1.4. Check the RF part 9.1.4.1. Finding out the Defective part After All the Checkings or Repairing 1. Re-register the checked Handset to the checked Base Unit, and Regular HS to Regular BU. Note: If you need to register a handset, refer to Registering a Handset to a Base Unit (P.22)
  • Page 44 KX-TG8421HGN/KX-TGA840FXN 9.1.4.2. RF Check Flowchart Each item (1 ~ 3) of RF Check Flowchart corresponds to Check Table for RF part (P.45). Please refer to the each item. Note: (*1) Base unit - refer to (G) of Check Point (Base Unit) (P.48)
  • Page 45 KX-TG8421HGN/KX-TGA840FXN 9.1.4.3. Check Table for RF part Item BU (Base Unit) Check HS (Handset) Check Link Confirmation Normal 1. Register Regular HS to BU (to be 1. Register HS (to be checked) to Regular checked). HS, BU Mode: [Normal mode] 2.

  • Page 46: Check Handset Transmission

    KX-TG8421HGN/KX-TGA840FXN 9.1.5. Check Handset Transmission Cross Reference: Signal Route (P.14) 9.1.6. Check Handset Reception Cross Reference: How to Check the Handset Speaker or Receiver (P.71). Signal Route (P.14) 9.1.7. Check Caller ID Cross Reference: Signal Route (P.14)

  • Page 47: Base Unit

    KX-TG8421HGN/KX-TGA840FXN 9.1.8. Bell Reception 9.1.8.1. Base Unit 9.1.8.2. Handset Cross Reference: Telephone Line Interface (P.10) Check Link (P.39) How to Check the Handset Speaker or Receiver (P.71) 9.1.9. Check TAM Operation Cross Reference: Power Supply Circuit (P.9) Note: (*1) When replacing FLASH MEMORY (IC421), TAM data need to be written to it. Refer to Base Unit of Things to Do after...

  • Page 48: Troubleshooting By Symptom (Base Unit And Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 9.2. Troubleshooting by Symptom (Base Unit and Charger Unit) If your unit has below symptoms, follow the instructions in remedy column. Remedies depend on whether you have DECT tester (*1) or not. Note: (*1) A general repair is possible even if you don’t have the DECT tester because it is for confirming the levels, such as Acoustic level in detail.
  • Page 49 KX-TG8421HGN/KX-TGA840FXN Items Check Procedure Check or Point Replace Parts (H)* Hookswitch Check with 1. Connect Telephone Socket to Tel-simulator which is connected with 600 Ω. L1, L2, Q3, R14, DC Characteristics 2. Set line voltage to 48 V and line current to 40mA at off-hook condition of nor- R15, Q4, R16, mal telephone.
  • Page 50 KX-TG8421HGN/KX-TGA840FXN Items Check Procedure Check or Point Replace Parts (M)* Frequency Drift Confir- Follow steps 1 to 6 of (J). IC7, mation ANTI_TP 7.Confirm that the frequency drift is < ± 35 kHz/ms. C802~C806, C808~C814, C820, C819, C822, C823, C825, C827,...
  • Page 51 KX-TG8421HGN/KX-TGA840FXN Items Check Procedure Check or Point Replace Parts Audio Check 1. Link with Handset. IC7, SA1, L1, 2. Input -45dBm/1kHz to MIC of Handset. L2, D3, Q3, Q4, Measure the Level at Line I/F and distortion level. R14, R15, R16, 3.

  • Page 52: Troubleshooting By Symptom (Handset)

    KX-TG8421HGN/KX-TGA840FXN 9.3. Troubleshooting by Symptom (Handset) If your unit has below symptoms, follow the instructions in remedy column. Remedies depend on whether you have DECT tester (*1) or not. Note: (*1) A general repair is possible even if you don’t have the DECT tester because it is for confirming the levels, such as Acoustic level in detail.
  • Page 53 KX-TG8421HGN/KX-TGA840FXN Items Check Procedure Check or Point Replace Parts (F)* Battery Monitor Check 1. Apply 2.25 V between BATT+ and BATT-. IC1, F1, C1, 2. Execute the command R12, R45 sendchar PAD sendchar LED 0 sendchar CRX 0 1 sendchar AD1 It assumes that the return value is XX.
  • Page 54 KX-TG8421HGN/KX-TGA840FXN Items Check Procedure Check or Point Replace Parts (K)* Frequency Offset Confir- Follow steps 1 to 3 of (I). IC1, mation 4.Confirm that the frequency Offset is < ± 50 kHz. C802~C806, C808~C814, C819~C820, C822, C825~C827, C834, C859~C864, L801~L804,...
  • Page 55 KX-TG8421HGN/KX-TGA840FXN 9.3.2. Troubleshooting for Speakerphone When the customer’s telephone line corresponds to the following conditions, and the transmission signal of SP-Phone is inter- rupted, performing the next set up to a cordless handset will improve it to some extent. Conditions 1.

  • Page 56: Disassembly And Assembly Instructions

    KX-TG8421HGN/KX-TGA840FXN 10 Disassembly and Assembly Instructions 10.1. Disassembly Instructions 10.1.1. Base Unit...
  • Page 57 KX-TG8421HGN/KX-TGA840FXN...
  • Page 58 KX-TG8421HGN/KX-TGA840FXN 10.1.2. Handset...
  • Page 59 KX-TG8421HGN/KX-TGA840FXN 10.1.3. Charger Unit...

  • Page 60: How To Replace The Handset Lcd

    KX-TG8421HGN/KX-TGA840FXN 10.2. How to Replace the Handset LCD...

  • Page 61: Measurements And Adjustments

    KX-TG8421HGN/KX-TGA840FXN 11 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.36) 11.1. Equipment Required • Digital multi-meter (DMM): it must be able to measure voltage and current.
  • Page 62 KX-TG8421HGN/KX-TGA840FXN 11.2.2. How to install Batch file into P.C. Note: • “*****” varies depending on the country or models. 11.2.3. 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”...

  • Page 63: Adjustment Standard (Base Unit)

    KX-TG8421HGN/KX-TGA840FXN 11.3. Adjustment Standard (Base Unit) When connecting the simulator equipments for checking, please refer to below. 11.3.1. Bottom View Note: (A) - (T) is referred to Check Point (Base Unit) (P.48)

  • Page 64: Adjustment Standard (Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 11.4. Adjustment Standard (Charger Unit) When connecting the simulator equipment for checking, please refer to below. 11.4.1. Bottom View Digital Volt Meter /2 W DC POWER DC 6.5 V Note: (A) is referred to Check Point (Charger Unit) (P.51)

  • Page 65: The Setting Method Of Jig (Handset)

    KX-TG8421HGN/KX-TGA840FXN 11.5. The Setting Method of JIG (Handset) This section explains the PC setting to use command required in Check Point (Handset)(P.52). <Preparation> Note: *: If you have the JIG Cable for TCD500 series • Serial JIG cable: PQZZ1CD300E* (PQZZ1CD505E), change the following values of resis- •...
  • Page 66 KX-TG8421HGN/KX-TGA840FXN 11.5.2. How to install Batch file into P.C. Note: • “*****” varies depending on the country or models. 11.5.3. 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”...

  • Page 67: Adjustment Standard (Handset)

    KX-TG8421HGN/KX-TGA840FXN 11.6. Adjustment Standard (Handset) When connecting the simulator equipments for checking, please refer to below. 11.6.1. Component View Note: (A) - (R) is referred to Check Point (Handset) (P.52)

  • Page 68: Things To Do After Replacing Ic Or X'tal

    KX-TG8421HGN/KX-TGA840FXN 11.7. Things to Do after Replacing IC or X'tal If repairing or replacing BBIC (FLASH type), EEPROM and X'tal, it is necessary to download the required data such as Program- ming data or adjustment data, etc in memory. The set doesn't operate if it is not executed.
  • Page 69 KX-TG8421HGN/KX-TGA840FXN 11.7.1.2. Handset First, operate the PC setting according to The Setting Method of JIG (Handset)(P.65). Then download the appropriate data according to the following procedures. Items How to download/Required adjustment BBIC (FLASH type) Programming data is stored in memory.

  • Page 70: Rf Specification

    KX-TG8421HGN/KX-TGA840FXN 11.8. RF Specification 11.8.1. Base Unit Item Value Refer to -. * TX Power 19 dBm ~ 25 dBm Check Point (Base Unit) (J) Modulation -370±30/+370±30 kHz/div & Modulated Check Point (Base Unit) (K) width 690 kHz Frequency Offset...

  • Page 71: How To Check The Handset Speaker Or Receiver

    KX-TG8421HGN/KX-TGA840FXN 11.9. 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. 11.10. Frequency Table (MHz) BASE UNIT...

  • Page 72: Miscellaneous

    KX-TG8421HGN/KX-TGA840FXN 12 Miscellaneous 12.1. CPU Data (Base Unit) 12.1.1. IC7 (BBIC) Pin No. Description Connection at Normal mode at Reset mode VSS_LNA1 RF_RXp RF_RXp RF_RXn RF_RXn VSS_LNA2 RFP1 RXON O_0/1 Hi-Z RFP0 ANT1 O_0/1 Hi-Z REF_RES REF_RES AVS_XTAL XTAL2 XTAL2...
  • Page 73 KX-TG8421HGN/KX-TGA840FXN Pin No. Description Connection at Normal mode at Reset mode P0_1/URX I_0/1 P0_0/UTX O_0/1 RSTn RSTn O_0/1 JTAG D.I/O JTAG I/O_0/1 I-PU P2_5/PCM_FSC/SF EEP_WP P2_4/SCL1/PCM_DO/ TEST P2_3/SDA1/PCM_DI/DP2 N.C. P2_2/PCM_CLK/CLK100 N.C. P2_1/ECZ2/PWM1/LED4 LED2 P2_0/ECZ1/PWM0/LED3 LED1 VDD2 +1.8V LDORF_CTRL LDORF_CTRL RF_SUPPLY2...

  • Page 74: Cpu Data (Handset)

    KX-TG8421HGN/KX-TGA840FXN 12.2. CPU Data (Handset) 12.2.1. IC1 (BBIC) Pin No. Description Connection at Normal mode at Reset mode VSS_LNA1 RF_RXp RF_RXp RF_RXn RF_RXn VSS_LNA2 RFP1 RXON O_0/1 RFP0 ANT1 O_0/1 REF_RES REF_RES AVS_XTAL XTAL2 XTAL2 XTAL1 XTAL1 AVD_XTAL AVD_XTAL RF_SUPPLY1...
  • Page 75 KX-TG8421HGN/KX-TGA840FXN Pin No. Description Connection at Normal mode at Reset mode JTAG D.I/O JTAG D.I/O I-PU P2_5/PCM_FSC/SF LCD_CSB I-PU P2_4/SCL1/PCM_DO/ N.C. P2_3/SDA1/PCM_DI/DP2 N.C. P2_2/PCM_CLK/CLK100 LCD_RESET P2_1/ECZ2/PWM1/LED4 N.C. P2_0/ECZ1/PWM0/LED3 BELL_LED_A VDD2 +1.8V LDORF_CTRL N.C. RF_SUPPLY2 RF_SUPPLY2 RF0n ANT2 RFP4 RFP3 PSEL...

  • Page 76: How To Replace The Flat Package Ic

    KX-TG8421HGN/KX-TGA840FXN 12.3. 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.
  • Page 77 KX-TG8421HGN/KX-TGA840FXN 12.3.3. 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.

  • Page 78: How To Replace The Llp (Leadless Leadframe Package) Ic

    KX-TG8421HGN/KX-TGA840FXN 12.4. How to Replace the LLP (Leadless Leadframe Package) IC 12.4.1. 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 79 KX-TG8421HGN/KX-TGA840FXN 12.4.4. 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. : PNMC1013Z 1. Put the shield case. 2. Solder the surroundings.

  • Page 80: Terminal Guide Of The Ics, Transistors And Diodes

    KX-TG8421HGN/KX-TGA840FXN 12.5. Terminal Guide of the ICs, Transistors and Diodes 12.5.1. Base Unit 12.5.2. Handset...

  • Page 81: Schematic Diagram

    KX-TG8421HGN/KX-TGA840FXN 13 Schematic Diagram 13.1. For Schematic Diagram 13.1.1. Base Unit (Schematic Diagram (Base Unit)) Notes: 1. DC voltage measurements are taken with voltmeter from the negative voltage line. 2. The schematic diagrams may be modified at any time with the development of new technology.

  • Page 82: Schematic Diagram (Base Unit)

    KX-TG8421HGN/KX-TGA840FXN 13.2. Schematic Diagram (Base Unit) ANT1_TP ANT2_TP ANT_1 ANT_2 C851 C853 W 0.15mm W 0.15mm L 22+/-4mm L 22+/-4mm Beep 1st or 4th layer 1st or 4th layer Bell signal DA802 *R86 W 0.15mm L 22+/-4mm 1st or 4th layer W 0.15mm...
  • Page 83 KX-TG8421HGN/KX-TGA840FXN Loop Current LINE_DC *R30 100k (1005) NC C155 6.8k *R13 TP10 *R20 3.9k R116 2.2k 100k +1.8V +1.8V 100k GND GND HAK_CL1 Caller ID RX_AF Bell signal 0.001 180k *C147 TX _AF 0.001 180k *C148 Bell signal 1.8V 3.0V 0.022...

  • Page 84: Schematic Diagram (Base Unit_Operation)

    KX-TG8421HGN/KX-TGA840FXN 13.3. Schematic Diagram (Base Unit_Operation) 2APVCC LED902 MEG_LED LED901 ANS_LED KEYS_B KEYIN1 KEYIN2 KEYIN3 KEYS_C KEYS_D KEYS_E ANS1 ERASE MSG2 SKIP MSG1 DOWN LOCAT/INT STOP KX-TG8421 SCHEMATIC DIAGRAM (Base Unit_Operation)
  • Page 85 KX-TG8421HGN/KX-TGA840FXN Memo...

  • Page 86: Schematic Diagram (Handset)

    KX-TG8421HGN/KX-TGA840FXN 13.4. Schematic Diagram (Handset) Charge Current BATTERY BATT+ 5.6n C1 CP1 BATTERY 6.3V 330u To Battery C150 R330 BATT- C331 R331 C2 CP2 6.3V C332 330u R332 X_CLK 2.5V 4.0V CP+2.5V CP+4.0V CP2.5V CP4.0V 1.2k 3.9k K10u CHG(+) K0.1u...
  • Page 87 KX-TG8421HGN/KX-TGA840FXN W 0.15mm L 20+/-2mm 1.8V 3rd layer (MAX500mA) R807 RXON +1.8V 1.8V L801 C827 C826 RX_RF K2.2u ANT_TP RF_RXn C859 C803 1.5p DA801 RF_RXp W 0.125mm L 7.6mm Gap 0.125mm W 0.15mm W 0.15mm 1st layer L 5.0mm L 5.0mm CP+2.5V...

  • Page 88: Schematic Diagram (Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 13.5. Schematic Diagram (Charger Unit) 10 (2W) SCHEMATIC DIAGRAM (Charger Unit)

  • Page 89: Printed Circuit Board

    KX-TG8421HGN/KX-TGA840FXN 14 Printed Circuit Board 14.1. Circuit Board (Base Unit_MAIN) 14.1.1. Component View R129 R130 C157 R126 C516 C506 R657 C515 C514 C513 C512 C861 R511 R808 R542 C511 C163 R532 R801 C517 R802 C860 C518 C520 C823 R805 IC801...
  • Page 90 KX-TG8421HGN/KX-TGA840FXN 14.1.2. Bottom View VDD4 (CP3.0V) (10.368MHZ) CHG- VDD1 1.8V CHG+ KX-TG8421 CIRCUIT BOARD (Base Unit_Main (Bottom View))

  • Page 91: Circuit Board (Base Unit_Operation)

    KX-TG8421HGN/KX-TGA840FXN 14.2. Circuit Board (Base Unit_Operation) 14.2.1. Component View PNLB1092Z KX-TG7431/8421/8431H LED901 ERASE ANS1 LED902 MSG1 MSG2 SKIP STOP LOCAT/INT DOWN KEYS_E KEYS_C KEYIN2 KEYS_B MEG_LED KEYS_D KEYIN3 KEYIN1 ANS_LED 2APVCC KX-TG8421 CIRCUIT BOARD (Base Unit_Operation (Component View))

  • Page 92: Circuit Board (Handset)

    KX-TG8421HGN/KX-TGA840FXN 14.3. Circuit Board (Handset) 14.3.1. Component View PNLB1104Z KX-TGA840XX EU RECEIVER RCV+ RCV- C152 C138 C139 L804 SPEAKER C863 C864 C814 C811 C804 IC801 C813 D14 D13 R802 L802 C802 R209 R208 JTAG R805 TEST C834 R225 C837 R807 R203 1.8V...
  • Page 93 KX-TG8421HGN/KX-TGA840FXN 14.3.2. Bottom View LED12 PNLB1104Z KX-TGA840XX EU C105 SOFT_C SOFT_A TALK LED4 LED1 LED5 LED2 LED6 LED3 CARBON_CL1 MIC- MIC+ KX-TGA840 CIRCUIT BOARD (Handset_Main (Bottom View))

  • Page 94: Circuit Board (Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 14.4. Circuit Board (Charger Unit) 14.4.1. Component View CIRCUIT BOARD (Charger unit (Component View)) 14.4.2. Bottom View TP4 (GND) CIRCUIT BOARD (Charger unit (Bottom View))

  • Page 95: Exploded View And Replacement Parts List

    KX-TG8421HGN/KX-TGA840FXN 15 Exploded View and Replacement Parts List 15.1. Cabinet and Electrical Parts (Base Unit) Note: (*1) Attach the double side tape to the exact location described above. (*2) Refer to the spacer (No.109) of Cabinet and Electrical Parts (Handset) (P.96)

  • Page 96: Cabinet And Electrical Parts (Handset)

    (*1) This cable is fixed by welding. Refer to How to Replace the Handset LCD (P.60). (*2) The rechargeable Ni-MH battery P03Por HHR-4MRE is available through sales route of Panasonic. (*3) Attach the spacer (No. 123) to the exact location described above.

  • Page 97: Cabinet And Electrical Parts (Charger Unit)

    KX-TG8421HGN/KX-TGA840FXN 15.3. Cabinet and Electrical Parts (Charger Unit)

  • Page 98: Accessories And Packing Materials

    KX-TG8421HGN/KX-TGA840FXN 15.4. Accessories and Packing Materials 15.4.1. KX-TG8421HGN...
  • Page 99 KX-TG8421HGN/KX-TGA840FXN 15.4.2. KX-TGA840FXN...

  • Page 100: Replacement Part List

    KX-TG8421HGN/KX-TGA840FXN 15.5. Replacement Part List Safety Ref. Part No. Part Name & Description Remarks 1. RTL (Retention Time Limited) PNBC1266Y1 BUTTON, ANSWER ON ABS-HB Note: PNBC1024Z1 BUTTON, STOP ABS-HB The “RTL” marking indicates that its Retention Time is PNBC1025Z1 BUTTON, LOCATOR...
  • Page 101 KX-TG8421HGN/KX-TGA840FXN Safety Ref. Part No. Part Name & Description Remarks Safety Ref. Part No. Part Name & Description Remarks PQ4R10XJ105 ECUV1H102KBV 0.001 PQ4R10XJ184 180k ECUV1C104KBV 0.1 PQ4R10XJ105 ECUV1C104KBV 0.1 ERJ3GEYJ104 100k F1K2H681A008 680p ERJ3GEYJ104 100k F1K2H681A008 680p ERJ2GEJ103 ECUE1E472KBQ 0.0047 ERJ2GEJ681 PQCUV1A225KB 2.2...
  • Page 102 KX-TG8421HGN/KX-TGA840FXN 15.5.2.2. Main P.C.Board Parts Safety Ref. Part No. Part Name & Description Remarks Note: C811 ECUE1H100DCQ 10p (*1) Reconfirm the model No. written on the handset’s name C812 ECUE1H100DCQ 10p plate when replacing PCB100. Because the model No. of C813 F1G1H2R2A480 2.2p...
  • Page 103 KX-TG8421HGN/KX-TGA840FXN Safety Ref. Part No. Part Name & Description Remarks Safety Ref. Part No. Part Name & Description Remarks ERJ2GEJ222 2.2k ECUE1H100DCQ 10p ERJ2GEJ821 ECUE1H100DCQ 10p ERJ2GEJ821 ECUE1H100DCQ 10p ERJ3GEYJ273 ECUE1H100DCQ 10p ERJ2GEJ104 100k ECUE1H100DCQ 10p ERJ2GE0R00 ECUE1H100DCQ 10p ERJ2GEJ104...
  • Page 104 ERG2SJ120 (FUSE) K5H302Y00003 FUSE 15.5.4. Accessories and Packing Materials Note: (*1) You can download and refer to the Operating Instruc- tions (Instruction book) on TSN Server. 15.5.4.1. KX-TG8421HGN Safety Ref. Part No. Part Name & Description Remarks PQLV219CEX AC ADAPTOR...

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