Kenwood KCH-20R User manual

SERVICE MANUAL
COPYRIGHT © 2015 JVC KENWOOD Corporation No.RA027<Rev.001>
2015/6
B5B-7206-00
REMOTE CONTROL HEAD
RA027<Rev.001>20156SERVICE MANUALB5B-7206-00
KCH-20R
COPYRIGHT © 2015 JVC KENWOOD Corporation
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
2 SPECIFIC SERVICE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14
This product complies with the RoHS directive for the European market. This product uses Lead Free solder.

1-2 (No.RA027<Rev.001>)
Document Copyrights
Copyright 2015 by JVC KENWOOD Corporation. All rights reserved.
No part of this manual may be reproduced, translated, distributed, or transmitted in any form or by any means, electronic, mechan-
ical, photocopying, recording, or otherwise, for any purpose without the prior written permission of JVC KENWOOD Corporation.
Disclaimer
While every precaution has been taken in the preparation of this manual, JVC KENWOOD Corporation assumes no responsibility
for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein.
JVC KENWOOD Corporation reserves the right to make changes to any products herein at any time for improvement purposes.
Bluetooth Copyrights
The Bluetooth word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by
JVC KENWOOD Corporation is under licence. Other trademarks and trade names are those of their respective owners.
SECTION 1
PRECAUTION
This service manual does not describe PRECAUTION.
R

(No.RA027<Rev.001>)1-3
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
2.1 INSTALLATION
2.1.1 Installing the Remote control head (KCH-20R)
The KCH-20R control head is used to remotely operate the
NX-5700/5800 series transceiver.
The KCH-20R is connected to the KCT-71 remote control cable.
The KRK-15B is connected to the NX-5700/5800 RF Deck with
the KCT-71.
2.1.2 Connection image
2.1.3 DIP Switch setting
All DIP switches for single remote (KCH-20R and KRK-15B)
must be set as "ON".
2.1.4 Remove the Operation panel from the transceiver
(NX-5700, NX-5800 only)
(1) Lift the two tabs of the panel on the bottom of the transceiv-
er with a flat-head screwdriver and remove the panel from
the chassis. (Fig. 1)
Fig.1
(2) Remove the flat cable from the display unit connector
(CN6) of the panel.
(3) Remove the cable from the display unit connector (CN2) of
the panel.
2.1.5 Install the KRK-15B onto the NX-5700, NX-5800 RF
Deck
(1) Insert the cable into the interface unit (XC3-0090-20) con-
nector (CN2) of the KRK-15B.
(2) Insert the flat cable into the interface unit connector (CN1)
of the KRK-15B. (Fig. 2)
Fig.2
Note:
The blue line of the flat cable and the flap of connector
are as same side.
After inserting, the flat cable should be locked with the
connector (flap) surely.
(3) Fit the KRK-15B with four tabs onto the front of the chassis.
(Fig. 3)
Fig.3
Note:
When installing the KRK-15B onto the front of the chas-
sis, hold down the flat cable with your fingers to prevent
it from being caught.
NX-5700/5800
RF Deck
KCT-71
Remote Control Cable
KRK-15B
Featured Panel
KCH-20R
KCT-72
Connection Cable
KCH-20R
1 2 3 4 ON
KRK-15B
1 2 3 4 ON
KRK-15BCN1
CN2
RF Deck

1-4 (No.RA027<Rev.001>)
2.1.6 Connect the KRK-15B and KCH-20R with the KCT-71
(1) Insert one lead wire with connector of the KCT-71 into the
connector (CN3) of the KRK-15B. (Fig. 4)
Fig.4
(2) Secure the cable bush as shown in the figure 5 and attach
the waterproof packing.
Note:
There is a direction to the installing of the cable bush.
Fig.5
(3) Slide the molding cover so as not to float the waterproof
packing and attach so that it is locked. (Fig. 6)
Fig.6
(4) Insert the other lead wire with connector of the KCT-71 into
the connector (CN5) of the KCH-20R.(Fig. 7)
Fig.7
(5) Attach the waterproof packing and molding cover in the
same way of step 2 and 3.(Fig. 8) (Fig. 9)
Fig.8
Fig.9
KCT-71 lead wire with connector
KRK-15B
CN3
Waterproof Packing
Cable Bush
Molding Cover
KCH-20R
KCT-71 lead wire with connector
CN5

(No.RA027<Rev.001>)1-5
2.1.7 Fixing method of KCH-20R microphone cord
This mounting hardware is intended to protect the modular
jack under use environment.
(Microphone can be used without this mounting hardware.)
Microphone cord should be fixed so that the curl portion is lower
side.
Refer to the following figs
Fig.10
Fig.11
Fig.12
PAN HEAD SEMS SCREW
(N67-3006-43)
MOUNTING HARDWARE
(J2B-0051-00)
Fixing the Microphone cord
NG: Curly cord upper side OK: Curly cord lower side

1-6 (No.RA027<Rev.001>)
2.2 CIRCUIT DESCRIPTION (KCH-20R)
2.2.1 Overview
KCH-20R is a remote control panel with 2.75" LCD and extended keys. KCH-20R has built-in Bluetooth and micro SD card slot. The
Bluetooth supports HSP. KCH-20R has two circuit units. XC3-010 is Sub unit and XC3-011 is Interface unit. There consist of a power
supply circuit, audio circuit, control circuit and the Bluetooth circuit.
2.2.2 Power supply circuit
SB is provided from Mobile Deck (NX-5700 or NX-5800) when Mobile DECK turns on. SB is connected to modular jack , IC1 and IC2.
IC1 regulates SB voltage to 5.36V(53DC) and IC2 regulates SB voltage to 3.9V(39DC). Both ICs operate whenever SB is supplied.
53DC is the power supply for Class-D Audio Amplifier, CAN transceiver, IC8(50D) and each LED.
39DC is the power supply for all DC/DC and regulators except for IC1(53DC), IC2(39DC).
A1 regulates 39DC to 1.2V(12D) and 12D provides the power to MPU core.
IC5 outputs 1.8V(18D) while 12D is operating. 18D provides the power to MPU I/O, DDR, Codec DSP and enables each regula-
tor(IC3, IC4, IC6). 18D_Flash is the power supply for Flash memory. After 33D turns on, IC10(switch IC) operates and 18D_Flash
starts working.
IC8 regulates 5.36V(53DC) to 5.0V(50D) and provides the power to Level shift circuit and Audio circuit. 50D is enabled while 18D is
operating.
IC3, IC4 and IC6 is provided 3.9V(39DC) and while 18D is operating, each IC outputs 3.0V(30LCD), 3.3V(33A) and 3.3V(33D).
30LCD is the power for LCD module. 33A is the power for Audio circuit and Codec analog section. 33D is the power for MPU I/O,
Codec I/O, CAN transceiver and Flash memory.
IC9 regulates 3.9V(39DC) to 3.3V(33SD). 33SD is the power for SD Circuit. When SD Card is used, MPU outputs 33SDC High signal
and IC9 starts working.
Power supply diagram is described Fig. 1.

(No.RA027<Rev.001>)1-7
Fig.1 Power supply diagram
External Interface
XC3-011
Level shift circuits,
Audio circuits
MPU core
Flash memory
CAN transceiver,
Flash memory,
Bluetooth circuits
CAN transceiver
Modular Interface
XC3-010
CN5 SB
IC1
5.4V DC/DC
53DC
CN13
CN1
Class-D Audio Amplifier
18D
IC8
5V AVR
53DC
50D
SB
12D
39DC
IC2
3.9V DC/DC
12D Q1
Level shift
A1
1.2V DC/DC
IC5
1.8V DC/DC
18D
IC10
Switch
18D_Flash
33D
IC6
3.3V AVR
33D
18D
18D
18D
“33SDC”
3.3V AVR
IC9 33SD SD Circuit
LCD module
30LCD
IC3
3.0V AVR
3.3V AVR
IC4 33A Audio circuits,
Codec Analog section
MPU I/O,CodecI/O,
MPU,Mobile DDR,
Codec DSP,
Bluetooth circuits
Key backlight/LED indicator

1-8 (No.RA027<Rev.001>)
2.2.3 Audio circuit
2.2.3.1 RX Audio
KCH-20R has two RX Audio input channels, AFIA+/- and AFIB+/-. And the MPU selects the one of the two channels, and then applied
to digital potentiometer IC (IC22/XC3-010). (The channel to use is notified by serial communication from RF Deck.)
The digital potentiometer IC adjusts RX Audio signal amplitude equal to the value of selected volume step, and output it.
RX signal through digital potentiometer IC is put into codec IC (IC17/XC3-010). KCH-20R has several output method of RX audio
signal (Speaker port, Bluetooth headset, and micro SD card recording). When use speaker output path, this audio signals pass through
to output port of codec IC. When use other output method, codec IC convert this signal to digital data, and transmits to the MPU (IC14/
XC3-010).
That analog output signal from codec IC is converted to balanced signal by operational amplifier (IC18/XC3-010).
And converted signal goes to Class-D audio amplifier (IC2/XC3-011). The audio amplifier is controlled to shut-down or power-up, by
MPU.
2.2.3.2 TX Audio
KCH-20R has four microphone input channels. First one is connected to modular interface (J2/XC3-010), second is connected to
external interface connector (CN2/XC3-011). Third is Bluetooth headset. Fourth is micro SD recording playback. When use modular
interface or external interface, these two microphone signals are selected by analog multiplexer IC (IC29/XC3-010), and applied to
microphone amplifier. The microphone amplifier consists of operational amplifier and AGC. And its output is connected to Codec IC.
The total gain of amplifiers in Codec IC is set to 0dB. The output signal of codec IC is converted to balanced signal by operational
amplifier (IC28/XC3-010). The converted signals are switched by analog switch IC (IC35/XC3-010, IC36/XC3-010), and output to ei-
ther MICA+/- or MICB+/-. The output channel is notified from RF Deck by serial communication.
Fig.2 Audio Circuit
2.2.4 Control circuit
The control circuit consists of MPU (IC14/XC3-010) and its peripheral circuits. IC14(XC3-010) mainly performs the followings;
(1) Serial communication between RF deck and KCH-20R.
(2) Controlling the audio circuits including codec IC.
(3) Controlling the display, and micro SD card.
(4) Controlling the Bluetooth circuit.
2.2.4.1 MPU
The MPU is 32bit RISC processor, equipped with peripheral functions. The maximum operating clock of MPU is 288MHz, and power
source are 3.3V/1.8V/1.2V DC. The MPU controls the flash memory, Mobile DDR, the audio circuits, the key-matrix, external I/O cir-
cuit, the display (LCD), the Bluetooth, and the micro SD card.
Analog SW
Analog SW
Digital
Potentiometer
Codec
OP AMP
OP AMP
Analog SW
Analog SW
AGC
Multiplexer
XC3-010XC3-011
CN5 RX Audio CN13
IC2
Audio
Power AMP
TX Audio
CN2
CN1
AFiA+
AFiB+
AFiA-
AFiB-
AFO+
AFO-
MICA+
MICB+
MICA-
MICB-
ACC_MIC
MIC
J2
IC29
IC36
IC35
IC15
IC16
IC19
IC22
IC18
IC28
OP AMP
D37,D38,Q17
IC23
IC17

(No.RA027<Rev.001>)1-9
2.2.4.2 Memory Circuit
Memory circuit consists of the MPU and the Mobile DDR (IC23/XC3-010), the flash memory (IC29/XC3-010). The flash memory has
capacity of 256Mbit that contains the program for the MPU and stores the data. That program can be easily updated from external
devices. The Mobile DDR has capacity of 512Mbit. The MPU copies the program from the flash memory to the Mobile DDR. The MPU
uses the Mobile DDR as a work area.
2.2.4.3 Serial interface between RF deck and KCH-20R
KCH-20R is controlled by serial interface from RF deck. That interface consists of CAN transceiver (IC1/XC3-010), but that does not
support CAN protocol. UART communication is used between CAN transceiver and MPU.
2.2.4.4 LCD control interface
The MPU controls LCD through the LCD interface connector (CN57/XC3-010). LCD is controlled by parallel bus with 16bit data width.
2.2.4.5 Key detection
KCH-20R has 19 keys. The keys except the AUX key and Power key is included in key-matrix circuit. Key-matrix consists of 4 input
ports and 5 output ports. When key is pressed, the MPU starts scanning the keys and detects which key was pressed.
AUX key is connected to MPU independently. The power key is connected to RF deck through the RF deck interface connector (CN5/
XC3-011).
2.2.4.6 External I/O
KCH-20R has external interface connector (CN2/XC3-011). That interface has two output and two input terminals.
The output terminal is open collector type. The input terminal has level shift circuit, it permits input the 5V signal.
2.2.4.7 micro SD circuit
The micro SD card interface consists of 4bit data bus and control signals. Maximum data transfer speed is 36MHz.
2.2.5 Bluetooth Circuit
The main component of the Bluetooth circuit is Bluetooth IC (IC12/XC3-010) and level converter circuit.
The clocks of Bluetooth IC requires 19.2MHz for core and 32.768kHz slow clock (X1/XC3-010 and X2/XC3-010) for UART.
Bluetooth IC communicates to the MPU (IC14/XC3-010) on the HCI UART. Interface of UART & Digital audio (I2S) between the MPU
and the Bluetooth IC, have level conversion at the level converter IC (IC13/XC3-010 and IC11/XC3-010).
The Bluetooth IC is powered by 1.8V and 3.3V which are supplied from 2 discrete external regulators (IC5/XC3-010 and IC6/XC3-
010).
TX/RX frequency is 2400-2483.5MHz (79ch Hopping, 2402-2480MHz, 1MHz step). Transmitting power is +2dBm at Bluetooth an-
tenna input.
Bluetooth antenna is surface mount chip antenna (ANT1/XC3-010), and that is connected to the Bluetooth IC through the LC filter
(L30/XC3-010).
Fig.3 Bluetooth Circuit
Frequency configuration for Bluetooth is following:
There are two LO modes: 2X and Offset LO (OSLO). 2X where LO is 2*RF_FREQ (e.g. when transmitting at 2441MHz it is at
4882MHz). OSLO where LO is at (2/3)*RF_FREQ (e.g. when transmitting at 2441MHz it is at 1627.333MHz).
In RX the 2X is always used.
In GFSK TX if power is 10dBm or more then OSLO is used.
In EDR2 TX if power is -12dBm or more then OSLO is used.
In EDR3 TX if power is -12dBm or more then OSLO is used.
Otherwise 2X is used for TX as well.
Converter
Level
Converter
UART
PCM
Antenna
IC14
MPU
X1
19.2MHz
RF SW
D31/Q8
3.3V
3.3V
IC13
Level
IC11
1.8V 1.8V
IC12
Bluetooth IC
L30
LC Filter
X2
32.768kHz
ANT1
Bluetooth

1-10 (No.RA027<Rev.001>)
2.3 COMPONENTS DESCRIPTION
2.3.1 Sub unit (XC3-0100-20)
2.3.2 Interface unit (XC3-0110-20)
Ref. No. Part Name Description
A1 DC-DC
CONVERTER
DC-DC CONVERTER (12DC)
IC1 MOS IC CAN transceiver IC
IC2 MOS IC DC-DC Converter (39DC)
IC3 MOS IC Voltage regulator (30LCD)
IC4 MOS IC Voltage regulator (33A)
IC5 MOS IC Voltage regulator (18D)
IC6 MOS IC Voltage regulator (33D)
IC7 MOS IC Voltage detector IC
IC8 MOS IC Voltage regulator (50D)
IC9 ANALOG IC Voltage regulator (33SD)
IC10 MOS IC DC switch
IC11 MOS IC Level converter IC
IC12 MOS IC Bluetooth IC
IC13 MOS IC Level converter IC
IC14 MPU IC MPU
IC15,16 MOS IC Analog switch (AF)
IC17 MOS IC Codec IC
IC18,19 MOS IC AF amplifier
IC20 MOS IC Logic control
IC21 MOS IC Logic control
IC22 MOS IC D/A Converter IC
IC23 MOS IC DC/AF amplifier (Vref/AF)
IC24 SRAM IC SDRAM
IC25 MOS IC A/D Converter IC
IC26 MOS IC Analog switch
IC27,28 MOS IC AF amplifier
IC29 MOS IC Analog switch (AF)
IC30 ROM IC Flash memory
IC31 MOS IC Analog switch
IC32 MOS IC Logic control
IC34 MOS IC DC amplifier (Buffer/Vref)
IC35,36 MOS IC Analog switch (AF)
IC37 MOS IC Logic control
IC38 MOS IC LED Driver IC (LCD backlight)
PH1 PHOT
TRANSISTOR
Illuminance sensor
Q1 FET DC switch
Q2,Q3 FET DC switch (Open drain)
Q4 DIGI
TRANSISTOR
DC switch
Q5 TRANSISTOR Buffer amprifier (TCXO)
Q6 DIGI
TRANSISTOR
DC switch
Q7-Q14 FET DC switch
Q15,Q16 FET DC switch
Q17 TRANSISTOR Mic AGC
Q18 FET DC switch
D1, 2 VARISTOR ESD protection
D3 DIODE Reverse current prevention
D4-6 LED LED_Key Backlight
D7 DIODE Reverse current prevention
D8-10 LED LED_Key Backlight
D11 DIODE Reverse current prevention
D12-15 LED LED_Key Backlight
D16 DIODE DC-DC Converter (39DC)
D17 DIODE Reverse current prevention
D18-21 LED LED_Key Backlight
D22 DIODE Reverse current prevention
D23,24 ZENER DIODE Overvoltage protection
D25-28 LED LED_Key Backlight
D29,30 DIODE Reverse current prevention
D31 DIODE DC switch
D32 LED Green-LED_Indicator
D33 LED 3colors-LED_Indicator
D34 DIODE DC Level shifter
D36 DIODE DC Level shifter
D37,38 DIODE ARRAY Mic AGC Detection
D39 DIODE Overvoltage protection
D40 DIODE DC Level shifter
D41 ZENER DIODE Overvoltage protection
D42,43 VARISTOR ESD protection
D44 VARISTOR Current protection
D45,46 VARISTOR ESD protection
D47-51 ZENER DIODE ESD protection
D57 DIODE DC discharge
D58 LED Red-LED_Indicator
D59 DIODE DC smoothing
Ref. No. Part Name Description
IC1 MOS IC DC-DC CONVERTER (53DC)
IC2 ANALOG IC Audio power amplifier (class D)
D1 VARISTOR Current protection
D4 DIODE DC-DC CONVERTER (53DC)
D5 DIODE Reverse current prevention
D6 VARISTOR ESD protection
D7 VARISTOR ESD protection
D8 VARISTOR ESD protection
D9 VARISTOR ESD protection
Ref. No. Part Name Description