KX-TG6421CAM, KX-TG6421CAT, KX-TG6422CAT, KX-TGA641RUM, KX-TGA641RUT - Panasonic Telephone Service Manual (repair manual). Page 3

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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. 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 ---------------------------------------17

6.1. Connections------------------------------------------------17
6.2. Battery-------------------------------------------------------17

7 Operating Instructions-----------------------------------------19

7.1. Programmable Settings ---------------------------------19
7.2. Registering a Handset to a Base Unit---------------21
7.3. Copying Phonebook Entries ---------------------------21
7.4. Dialling Mode ----------------------------------------------22
7.5. Error Messages -------------------------------------------22
7.6. Troubleshooting-------------------------------------------23
7.7. For Service Hint-------------------------------------------27

8 Service Mode -----------------------------------------------------28

8.1. Engineering Mode ----------------------------------------28
8.2. Copying Phonebook Items when Repairing -------32
8.3. How to Clear User Setting------------------------------34

9 Troubleshooting Guide ----------------------------------------35

9.1. Troubleshooting Flowchart -----------------------------35
9.2. Troubleshooting by Symptom (Base Unit and

Charger Unit) ----------------------------------------------47

9.3. Troubleshooting by Symptom (Handset) -----------51

10 Disassembly and Assembly Instructions ---------------55

10.1. Disassembly Instructions -------------------------------55
10.2. How to Replace the Handset LCD -------------------59

11 Measurements and Adjustments---------------------------60

11.1. Equipment Required -------------------------------------60
11.2. The Setting Method of JIG (Base Unit) -------------60
11.3. Adjustment Standard (Base Unit)---------------------62
11.4. Adjustment Standard (Charger Unit)-----------------63
11.5. The Setting Method of JIG (Handset) ---------------64
11.6. Adjustment Standard (Handset) ----------------------66
11.7. Things to Do after Replacing IC or X'tal ------------67
11.8. RF Specification-------------------------------------------69
11.9. How to Check the Handset Speaker or

Receiver ----------------------------------------------------70

11.10. Frequency Table (MHz) ---------------------------------70

12 Miscellaneous ----------------------------------------------------71

12.1. CPU Data (Base Unit) -----------------------------------71
12.2. CPU Data (Handset)-------------------------------------73
12.3. How to Replace the Flat Package IC----------------75
12.4. How to Replace the LLP (Leadless Leadframe

Package) IC------------------------------------------------77

12.5. Terminal Guide of the ICs, Transistors and

Diodes ------------------------------------------------------ 79

13 Schematic Diagram -------------------------------------------- 81

13.1. For Schematic Diagram -------------------------------- 81
13.2. Schematic Diagram (Base Unit)---------------------- 82
13.3. Schematic Diagram (Base Unit_Operation) ------- 84
13.4. Schematic Diagram (Handset)------------------------ 86
13.5. Schematic Diagram (Charger Unit)------------------ 88

14 Printed Circuit Board ------------------------------------------ 89

14.1. Circuit Board (Base Unit_Main) ---------------------- 89
14.2. Circuit Board (Base Unit_Operation)---------------- 91
14.3. Circuit Board (Handset) -------------------------------- 93
14.4. Circuit Board (Charger Unit)--------------------------- 95

15 Exploded View and Replacement Parts List ----------- 96

15.1. Cabinet and Electrical Parts (Base Unit) ----------- 96
15.2. Cabinet and Electrical Parts (Handset)------------- 97
15.3. Cabinet and Electrical Parts (Charger Unit) ------- 98
15.4. Accessories and Packing Materials ----------------- 99
15.5. Replacement Part List -------------------------------- 102