Kenwood_TH-K2_serv.pdf

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1、144MHz FM TRANSCEIVER TH-K2AT/K2E/K2ET 2003-8 PRINTED IN JAPAN B51-8658-00 (S) 836 SERVICE MANUAL DISASSEMBLY FOR REPAIR .2 CIRCUIT DESCRIPTION .6 SEMICONDUCTOR DATA .14 COMPONENTS DESCRIPTION .15 PARTS LIST.17 EXPLODED VIEW.23 PACKING .25 ADJUSTMENT .27 TERMINAL FUNCTION.43 PC BOARD TX-RX UNIT (X57

2、-674X-XX) (A/3) .44 TX-RX UNIT (X57-674X-XX) (B/3),(C/3) . 48 CONTENTS SCHEMATIC DIAGRAM.50 LEVEL DIAGRAM.55 BLOCK DIAGRAM.56 BC-21 (WALL CHARGER) .58 PB-43N (Ni-MH BATTERY PACK) .58 BT-14 (BATTERY CASE) .59 PG-4Y (PROGRAMMING INTERFACE CABLE) . 59 MCP-1A (MEMORY CONTROL PROGRAM) . 59 SPECIFICATIONS

3、.BACK COVER Knob (ENC) (K29-5159-03) Knob (VOL) (K29-5150-03) Cabinet assy (16key) (A02-3819-23) Helical Antenna (T90-1018-25) Key top (16key) (K29-9272-02) Front glass (B10-2746-03)Knob (PTT/LAMP/MON) (K29-9274-03) Knob (ENC) (K29-5159-03) Knob (VOL) (K29-5150-03) Cabinet assy (4key) (A02-3818-23)

4、Helical Antenna (T90-1018-25) Key top (4key) (K29-9276-02) Front glass (B10-2746-03)Knob (PTT/LAMP/MON) (K29-9274-03) TH-K2AT/K2ETTH-K2E Cap (SP/MIC/DC IN) (B09-0675-03) Cap (SP/MIC/DC IN) (B09-0675-03) TH-K2AT/K2E/K2ET 2 DISASSEMBLY FOR REPAIR How to remove the case assembly from the chassis 1. Rem

5、ove two screws (z) holding the chassis. 2. Pull out two knobs (x) and remove two round nuts (c). 3. Pull out the SP and MIC parts of the cap from jacks (v). 4. Turn the unit over with the bottom of the chassis facing upwards, and remove the chassis (n) from the case assembly (b). 5. Remove the speak

6、er lead (m) from the connector (CN2) of the TX-RX PC board (TX-RX unit A/3). How to remove the PC board Numeric key PC board (TX-RX unit B/3) 1. Remove three screws (,) on the numeric key PC board. 2. Lift the numeric key PC board and remove it from the connector (CN9) of the TX-RX PC board (.). PTT

7、 PC board (TX-RX unit C/3) 3. Remove one screw on the PTT PC board (/). 4. Pull the PTT PC board to the left and remove it from the connector (CN6) of the TX-RX PC board (TX-RX unit A/3) (). TX-RX PC board (TX-RX unit A/3) 5. Remove the SP/MIC jack cover (). 6. Remove two screws () holding the shiel

8、d cover (antenna terminal section). 7. Remove two screws () holding the shield cover (final amplifier section). 8. Remove eight screws () on the TX-RX PC board. 9. Absorb solder from the antenna terminal () with a solder absorber. Note: Do not melt the shadow plate () when moving the tip of the sold

9、er absorber close to the antenna terminal. 10.Remove the TX-RX PC board from the chassis, then remove the encoder volume FPC () from the flat cable connector of the TX-RX PC board. CN2 CN9 CN6 x x c c v m b , , . / n z TX-RX unit (B/3) TX-RX unit (C/3) TX-RX unit (A/3) TH-K2AT/K2E/K2ET 3 DISASSEMBLY

10、 FOR REPAIR Soldering the antenna terminal 1. With the shield cover removed from the antenna terminal section, install two screws on the PC board and bring the PC board into contact with the chassis (z). 2. Solder the antenna terminal with a soldering iron (x). 3. Remove the two screws installed in

11、step 1 above, and install the two screws again on the PC board together with the shield cover (c). Replacing the final FET (Q12) 1. Remove the two screws holding the shield cover of the final FET section (z). 2. Remove solder from the shield cover completely with a solder absorber. (E and E3 types o

12、nly) 3. Remove the shield cover (x). z x c z x 4. Apply the tips of soldering irons to all the four pins of the final FET at the same time (c), heat them sufficiently, and remove the final FET (v). (Two persons should be required to do this.) 5. Remove all PC boards from the chassis. 6. Confirm that

13、 there is no space between the radiation plate installed on the foil side of the TX-RX PC board (TX-RX unit A/3) and the PC board (b). If there is any space between the radiation plate and PC board, eliminate it by applying the tip of the soldering iron to the radiation plate. 7. Apply the tip of th

14、e soldering iron to the installation side of the radiation plate of the TX-RX PC board, put a little amount of solder to the radiation plate that is seen through a square hole in the final FET installation section and melt the solder (n). 8. When the solder in step 7 is melted, place the final FET o

15、n the PC board by aligning it with the silk of the final FET installation section of the PC board (m). 9. Release the soldering iron and confirm that the final FET and radiation plate have been soldered. 10.Solder the four pins of the final FET with the soldering iron. 11.Install all the PC boards.

16、12.Reinstall the shield cover removed in step 3 above in its original position and install two screws. 13.Solder the shield cover to the PC board. (E and E3 types only) 14.Install the chassis on the case assembly and assemble them. 15.Readjust transmission power. Note: Since the FET is sensitive to

17、static electricity, always wear a grounding band. Use a highly insulated ceramic heater solder iron. Radiation plate TX-RX PC board b c v m n TH-K2AT/K2E/K2ET 4 DISASSEMBLY FOR REPAIR Special care and attention required for assembly 1. Gluing to the key top (MIC element section) You must also glue o

18、n the speaker storage area and heap the glue up until wealthy glued on the speaker storage area and the key top for waterproofing the MIC element side of the key top. (Fig. 1) Fig. 1 2.Bending the LCD hardware fixture (J21-8456-03) tabs (1)Insert the tabs of the LCD hardware fixture into four holes

19、in the LCD installing position of the TX-RX PCB (TX-RX unit A/3). (Fig. 2) Heap the glue up until wealthy glued on the speaker storage area and the key top (MIC element section). Fig. 2 (2)By pressing the LCD hardware fixture from the component side of the TX-RX PCB, you must bent all 4 tabs of the

20、LCD hardware fixture being visible from the foil side until the bases of each tabs are folded at least 45 degrees (Fig. 3). If the bending angle of the tabs of the LCD hardware fixture is less than 45 degrees, a display error may occur. Bending position NG NG Min 45 degrees 3. PTT PCB (TX-RX unit C/

21、3) installation procedure Installing the PTT PCB on the TX-RX PCB and chassis are as follows: (1)Insert the PTT PCB connector (CN7) into the TX-RX PCB connector (CN6) lightly. (2)Push three parts of the PTT PCB to contact tightly with the chassis. There may be a small gap between the connectors. (Fi

22、g. 4) Note: A double-side adhesive tape (J99-0376-04) is used behind the PTT switch. When reassembling the PTT PCB to the chassis, press the PTT PCB (under the PTT switch) so that the tape hold the PCB and chassis securely. Fig. 3 CN6 Chassis PTT switch PTT PCB (C/3) OK A bit clearance No clearance

23、NG CN6 CN7 CN7 Chassis PTT PCB (C/3) PTT switch Fig. 4 Push three parts of the PTT PCB to contact tightly with the chassis. (3)Tighten one screw in the PTT PCB. TH-K2AT/K2E/K2ET 5 DISASSEMBLY FOR REPAIR 4. Packing (G53-1572-02) TX/BUSY lamp installation procedure (1)To assure waterproofing, install

24、the packing in the chassis groove as shown in Fig. 5. (z) (2)Install the packing TX/BUSY lamp section on the chassis. (x) z x OK Packing NG Packing Chassis Chassis 5.Packing (G53-1572-02) bottom installation procedure (1)Before installing the numeric key PCB (TX-RX unit B/3) on the chassis, push thr

25、ee parts of the packing to contact tightly with the chassis as shown in Fig. 6. If the packing is not in contact with the chassis, there may be a gap between the transceiver bottom case assembly and the battery, and water may enter through the gap. Fig. 5 OKNG Push three parts of the packing to cont

26、act tightly with the chassis. Clearance NG Fig. 6 6.Cautions for installing the chassis on the case assembly (1)Verify that the packing (G53-1572-02) TX/BUSY lamp section is has been past through the hole in the illumination guide section on the top of the case assembly. (Fig. 7) LAMP LOW PTT Fig. 7

27、 (2)Align the speaker lead as shown fig.8. Do not place the leads over the key top section, LCD section or SP/MIC/DC IN cap section. Do not fix this part of the key top to the rib of the case assembly. 7.Cautions for installing the key top on the case assembly (1)Install the key top keypad section a

28、nd the power switch section on the rib of the case assembly. (2)Do not fix the part between the key top keypad section and the power switch section to the rib of the case assembly, but install it as shown in Fig. 8. The packing TX/BUSY lamp section is has been past through the hole in the illuminati

29、on guide section on the top of the case assembly. Fig. 8 TH-K2AT/K2E/K2ET 6 CIRCUIT DESCRIPTION Frequency Configuration The frequency configuration is shown in Figure 1 and Table 1. Fig. 1 Frequency configuration 174.850212.845MHz (K,K2,M,M2) 182.850184.845MHz (E,E3) 144.000147.995MHz(K,K2) 136.0001

30、73.995MHz(M,M2) 144.000145.995MHz(E,E3) 136.000173.995MHz(K,K2,M,M2) 144.000145.995MHz(E,E3) 144.000147.995MHz(K,K2) 136.000173.995MHz(M,M2) 144.000145.995MHz(E,E3) RX : TX : ANT SW MCF 38.85MHz 38.4MHz 12.8MHz 450kHz CF MIX, IF, DET AF AMP SP PRE DRIVE FINAL TCXO DRIVE Tripler x 3 RF AMP 1st MIX PL

31、L VCO MIC AMP MIC ANT Receiver System Front End The received signal from the antenna passes through a low- pass filter and then through a transmission/reception switching circuit (antenna switch) and enters the band-pass filter (L40, L41, L38). The signal passing through the band-pass filter (L40, L

32、41, L38) is amplified by with an RF amplifier (Q17), passes through a band-pass filter (L32, L35) and enters the first mixer (Q16). These band-pass filters are tuned to a desired frequency by varicaps (D21, D20, D19, D18). Double super heterodyne Reception method1st IF Frequency38.85MHz (Upper) 2nd

33、IF Frequency 450kHz (Lower) Transmission methodVCO direct oscillation amplification ModulationVariable reactance phase modulation Table 1 Basic configuration ANT SW SP LPF VCO BPF/APC MPU IC8 PLL IF AMP, DET Tripler x 3 TCXO BPF L41,L40,L38 BPF L32,L35 MIXER Q16 1st Local OSC (PLL) RF AMP Q17 ANT MC

34、F XF1 IF AMP Q24 FM IC IC3 Q23 2nd Local OSC X1 AF AMP IC6 5R5R D20D21 LV 6 Tuning voltage D18 38.85MHz 12.8MHz D19 A tuning voltage corresponding to the desired signal is applied to each varicap through the BPF/APC terminal (pin 6) of the MPU (IC8) to tune to the receive frequency. First Mixer The

35、received signal passing through the band-pass filter (L32, L35) is mixed with the first local signal generated by the VCO by the first mixer (Q16) to produce a first IF signal (38.85 MHz) (Upper heterodyne). The first IF signal passes through a MCF (Monolithic crystal filter: XF1) to remove unwanted

36、 components. The first IF signal passing through the MCF (XF1) is amplified by an IF amplifier (Q24) and the resulting signal enters the FM IC (IC3). Fig. 2 Receiver section configuration ItemRating Nominal center frequency (fo)38.85MHz Pass bandwidth6.0kHz or more at 3dB Attenuation bandwidth25kHz

37、or less at 35dB Ultimate attenuation70dB or more (fo 910 kHz) Spurious response40dB or more (fo +1MHz) Ripple1dB or less Insertion loss4dB or less Terminating impedance610 5% / 3pF 0.5pF Table 2 MCF (L71-0619-05) characteristics (TX-RX unit XF1) ItemRating Nominal center frequency (fo)450kHz 3dB ban

38、dwidth6.5kHz or more 50dB bandwidth15.5kHz or less Ripple2dB or less (fo 6.5kHz) 55dB or more Guaranteed attenuation(fo 18kHz to 33kHz) 50dB or more (fo 100kHz) Insertion loss4dB or less I/O matching impedance1.5k Table 3 Ceramic filter (L72-0968-05) characteristics (TX-RX unit CF1) TH-K2AT/K2E/K2ET

39、 7 CIRCUIT DESCRIPTION IF Circuit The first IF signal (38.85 MHz) amplified by the IF amplifier (Q24) and the second IF signal (38.4 MHz) generated by tripling the 12.8 MHz reference oscillator frequency of the TCXO (X1) by Q23, are mixed in the FM IC to produce a second IF signal (450 kHz) (Lower h

40、eterodyne). The second IF signal passes through a ceramic filter (CF1) to remove unwanted components. The second IF signal passing through the ceramic filter (CF1) passes through the IF amplifier in the FM IC again and is detected to produced an audio signal. Squelch and Mute Circuit A noise compone

41、nt is obtained by passing FM detection output (FM IC pin 9) through an operational amplifier in the CF1 450kHz CD1 AF OUT AFM SM SQ IC8 MPU 49 9 48 SMV SQV 161514131211109 12345678 MIX Local OSC Buffer RSSI Quadrature detector LPF Noise AMP IF AMP Inverter AMP 1st IF input (38.85MHz) IC3 FM IC 2nd l

42、ocal OSC (38.4MHz) 5R Q21 AF FILTER Q20 AF MUTE SWITCH VOL IN R135 C173C174 R125 R126 Noise comp Rectifier 5R SP AF OUT AF FILTER Q21 AF MUTE SWITCH Q20 IC6 AF AMP IC3 FM IC VR201 AF VOLUME DTMF/BEEP REM IC8 MPU SPK AFO SPG REM/TXD 40 46 9 J4 SP JACK Fig. 3 IF, Squelch, Mute and S meter circuit Fig.

43、 4 AF amplifier FM IC and band-pass filter consisting of R125, R126, R135, C173, C174. The noise component is rectified in the FM IC to produce a DC voltage, which is output from the N-REC terminal (pin 14) of the FM IC as squelch voltage. The squelch voltage enters the SQ terminal (pin 48) of the M

44、PU (IC8) and is compared with the reference voltage preset in the MPU to control audio signal ON/OFF. When L is output from the AFM terminal (pin 9) of the MPU, the AF mute switch (Q20) is activated to mute the audio signal. S Meter Circuit The S meter voltage is output from the RSSI terminal (pin 1

45、2) of the FM IC (IC3) and input to the SM terminal (pin 49) of the MPU. Then the voltage is converted from analog to digital in the MPU to control the S meter display on the LCD. AF Amplifier The detected audio signal passes through an AF filter (Q21) and enters an AF mute switch (Q20). After passin

46、g through the AF mute switch (Q20), the signal passes through an AF volume (VR201) and is amplified to a specified output level with an AF amplifier (IC6). The audio signal amplified with the AF amplifier (IC6) is output through an internal speaker or an external speaker jack (J4). The beep tone and

47、 the DTMF signal are output from the DTMF/BEEP terminal (pin 40) of the MPU (IC8), enters the AF amplifier (IC6) and is output as a monitor tone. TH-K2AT/K2E/K2ET 8 CIRCUIT DESCRIPTION Transmitter System Microphone Amplifier Circuit The audio signal from the microphone passes through a high-pass filter (IC5) and enters a microphone amplifier (IC16). The signal passes through a pre-emphasis circuit, limiter amplifier and splatter filte