KX-DT521RU - Panasonic Telephone Service Manual (repair manual). Page 2

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1 Safety Precautions -----------------------------------------------3

1.1. For Service Technicians  ---------------------------------3

2 Warning --------------------------------------------------------------4

2.1. About Lead Free Solder (PbF: Pb free) --------------4

2.1.1. Suggested PbF Solder -------------------------------4

2.2. Discarding of P. C. Board --------------------------------4

3 Specifications ------------------------------------------------------5
4 Technical Descriptions------------------------------------------6

4.1. Block Diagram ----------------------------------------------6
4.2. Circuit Operations ------------------------------------------7

4.2.1. LCD Circuit ----------------------------------------------7
4.2.2. Reset Circuit --------------------------------------------7
4.2.3. Data Communication ---------------------------------8
4.2.4. DXDP Communication -------------------------------9
4.2.5. Analog Circuit ---------------------------------------- 10
4.2.6. ASIC (IC300) ----------------------------------------- 11
4.2.7. ASIC (IC205) ----------------------------------------- 12
4.2.8. Key Circuit--------------------------------------------- 13
4.2.9. LED Circuit -------------------------------------------- 14

4.2.10. Power Supply Circuit ------------------------------- 16

5 Location of Controls and Components------------------ 17

5.1. Name and Locations ------------------------------------ 17

6 Installation Instructions--------------------------------------- 18

6.1. Connections ----------------------------------------------- 18

7 Test Mode ---------------------------------------------------------- 19

7.1. Function Test Mode-------------------------------------- 19

7.1.1. Preparation-------------------------------------------- 19
7.1.2. KEYs and LEDs Test ------------------------------- 19

8 Troubleshooting Guide---------------------------------------- 20

8.1. No Operation ---------------------------------------------- 20
8.2. ASIC1(IC300) Does Not Operate -------------------- 26
8.3. LCD Does Not Operate --------------------------------- 27
8.4. DXDP Does Not Work ---------------------------------- 28
8.5. Audio Problem -------------------------------------------- 29
8.6. Handset Does Not Work-------------------------------- 29

8.6.1. Receive ------------------------------------------------ 29
8.6.2. Send ---------------------------------------------------- 30

8.7. Headset Does Not Work-------------------------------- 31

8.7.1. Receive ------------------------------------------------ 31
8.7.2. Send ---------------------------------------------------- 32

8.8. Speaker-Phone/Ringer Does Not Work ------------ 32

8.8.1. Receive / Ringer ------------------------------------- 32
8.8.2. Send ---------------------------------------------------- 33

8.9. LED Does Not Light ------------------------------------- 34

9 Disassembly and Assembly Instructions --------------- 35

9.1. Remove Main Board and Ope Board --------------- 35
9.2. Remove and Assembly for LCD   -------------------- 36
9.3. Assembly for Lead wire--------------------------------- 37

10 Miscellaneous ---------------------------------------------------- 39

10.1. Terminal Guide of the ICs Transistors and

Diodes------------------------------------------------------- 39

10.1.1. Main Board-------------------------------------------- 39
10.1.2. Operation Board ------------------------------------- 39

10.2. How To Replace a Flat Package IC ----------------- 40

10.2.1. Preparation-------------------------------------------- 40
10.2.2. Removal Procedure--------------------------------- 40
10.2.3. Procedure --------------------------------------------- 40
10.2.4. Removing Solder From Between Pins --------- 40

10.2.5. Memo -------------------------------------------------- 41

11 Schematic Diagram -------------------------------------------- 42

11.1. Main No.1-------------------------------------------------- 42
11.2. Main No.2-------------------------------------------------- 44
11.3. Ope---------------------------------------------------------- 46
11.4. Waveform -------------------------------------------------- 48

11.4.1. No.(1)-(6)---------------------------------------------- 48
11.4.2.  No.(7)-(10) ------------------------------------------- 49
11.4.3. No.(11)-(12)------------------------------------------- 50
11.4.4. No.(13)-(15) ------------------------------------------ 51
11.4.5. No.(16)-(17) ------------------------------------------ 52

12 Printed Circuit Board------------------------------------------ 53

12.1. Main Board ------------------------------------------------ 53

12.1.1. Component View ------------------------------------ 53
12.1.2. Bottom View ------------------------------------------ 54

12.2. Operation Board ----------------------------------------- 55

12.2.1. Component(No.1) View --------------------------- 55
12.2.2. Component(No.2) View --------------------------- 56
12.2.3. MIC Board Component View--------------------- 56

13 Appendix Information of Schematic Diagram -------- 57
14 Exploded View and Replacement Parts List----------- 58

14.1. IC Data ----------------------------------------------------- 58

14.1.1. IC410--------------------------------------------------- 58
14.1.2. IC300--------------------------------------------------- 61
14.1.3. IC205--------------------------------------------------- 62

14.2. Cabinet and Electric Parts----------------------------- 63
14.3. Accessories and Packing Materials ----------------- 64
14.4. Replacement Parts List -------------------------------- 65

14.4.1. Cabinet and Electrical Parts---------------------- 65
14.4.2. Accessories and Packing Materials ------------ 65
14.4.3. Main Board Parts ----------------------------------- 65
14.4.4. Ope Board Parts ------------------------------------ 68