KX-TG2521CAT, KX-TGA251RUT - 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. Signal Route -----------------------------------------------13

5 Location of Controls and Components ------------------15
6 Installation Instructions ---------------------------------------15
7 Operating Instructions-----------------------------------------15

7.1. For Service Hint-------------------------------------------15

8 Service Mode -----------------------------------------------------16

8.1. Engineering Mode ----------------------------------------16
8.2. Copying Phonebook Items when Repairing -------20
8.3. How to Clear User Setting------------------------------22

9 Troubleshooting Guide ----------------------------------------23

9.1. Troubleshooting Flowchart -----------------------------23
9.2. Troubleshooting by Symptom (Base Unit) ---------35
9.3. Troubleshooting by Symptom (Handset) -----------39

10 Disassembly and Assembly Instructions ---------------42

10.1. Disassembly Instructions -------------------------------42
10.2. How to Replace the Handset LCD -------------------44

11 Measurements and Adjustments---------------------------45

11.1. Equipment Required -------------------------------------45
11.2. The Setting Method of JIG (Base Unit) -------------45
11.3. Adjustment Standard (Base Unit)---------------------47
11.4. The Setting Method of JIG (Handset) ---------------48
11.5. Adjustment Standard (Handset) ----------------------50
11.6. Things to Do after Replacing IC or X'tal ------------51
11.7. RF Specification-------------------------------------------53
11.8. How to Check the Handset Speaker or

Receiver ----------------------------------------------------54

11.9. Frequency Table (MHz) ---------------------------------54

12 Miscellaneous ----------------------------------------------------55

12.1. How to Replace the Flat Package IC ----------------55
12.2. How to Replace the Shield Case ---------------------57
12.3. Terminal Guide of the ICs, Transistors, Diodes

and Electrolytic Capacitors-----------------------------59

13 Schematic Diagram ---------------------------------------------60

13.1. For Schematic Diagram---------------------------------60
13.2. Schematic Diagram (Base Unit) ----------------------62
13.3. Schematic Diagram (Handset) ------------------------64

14 Printed Circuit Board-------------------------------------------67

14.1. Circuit Board (Base Unit_Main)-----------------------67
14.2. Circuit Board (Handset) ---------------------------------69

15 Exploded View and Replacement Parts List -----------71

15.1. Cabinet and Electrical Parts (Base Unit) -----------71
15.2. Cabinet and Electrical Parts (Handset) -------------72
15.3. Accessories ------------------------------------------------73
15.4. Replacement Part List-----------------------------------74