Contents
Revision History.....................................................................................................................................0
Introduction ............................................................................................................................................1
Radio Controls........................................................................................................................................2
Circuit Description .................................................................................................................................3
Description of Components ................................................................................................................20
Tuning....................................................................................................................................................22
Port Definition.......................................................................................................................................22
Troubleshooting Flow Chart......................... ... ... ... ... ... ... ... ... .... ... ... ... ... ... ... ... ... ... ... ... .... ... ... ... .............26
Disassembly and Re-assembly for Repair.........................................................................................31
Exploded View......................................................................................................................................34
Packing..................................................................................................................................................36
MD78X PCB View..................... ... ... ... ... ... .... ... ... ... ... ... ... ... ... ... ...............................................................36
MD78X Block Diagram ... ... ... ... ... ... ... ... ... .... ... ... ... ... ... ... ... ... ... ... .... ... ... ... ... ... ... ... ... ... .... ... ... ... ................36
Specifications.......................................................................................................................................37
Revision History
Material No. Date of
Issue
May 2010 Initial Release
Changes
Introduction
Manual Scope
This manual is intended for use by experienced technicians familiar with similar types of communication
equipment. It contains all service information required for the equipment and is current as of the
publication date.
This mobile radio shall be serviced by qualified technicians only.
Copyright Information
Hytera and HYT are the trademark or registered trademark of Hytera Communications Corporation
Limited (hereinafter referred to as “Hytera”) in PRC and other countries and/or areas. Hytera retains the
ownership of its trademarks and product names. All other trademarks and/or product names that may be
used in this manual are properties of their respective owners.
The Hytera product described in this manual may include Hytera computer programs stored in memory
or other media. Laws in the PRC and/or other countries or areas preserve for Hytera exclusive rights for
Hytera computer programs. The purchase of this product shall not be deemed to grant, either directly or
by implication, any rights to the purchaser with respect to Hytera computer programs. Any Hytera
computer programs may not be copied, modified, distributed, decompiled, or reverse-engineered in any
manner without the prior written consent of Hytera.
Disclaimer
Hytera endeavors to achieve the accuracy and completeness of this manual, but no warranty of
accuracy or reliability is given. All the specifications and designs are subject to change without prior
notice due to continuous technology development. Changes which may occur after publication are
highlighted by Revision History contained in Service Manual.
No part of this manual may be copied, modified, translated, or distributed in any manner without the
express written permission of Hytera.
1
Radio Controls
Front Panel
No. Part Name No. Part Name
1
○
3
○
5
○
7
○
9
○
11
○
Volume Control / Channel
Selector Knob
LCD Display
Back Key
Up Key
Speaker
Microphone Jack
2
○
4
○
6
○
8
○
10
○
12
○
LED Indicator
OK/Menu Key
Power On/Off Key
Down Key
Programmable Keys
Emergency key
(programmable)
2
Rear Panel
No. Part Name No. Part Name
1
○
3
○
Antenna Connector (BNC)
Accessory Jack
2
○
4
○
Power Inlet
GPS Antenna Connector
Circuit Description
1. Front Panel
The front panel provides parts including speaker, keys, power switch, volume control knob, LCD display
and etc. The block diagram is shown as the figure below:
3
Figure 1 Front Panel Block Diagram
1.1 Power Supply
The main board supplies power to the front panel via 5VD, so that RX/TX LED, backlight and USB
devices can be powered up. Power is further fed to U5 LDO, and then is supplied to LCD and
serial-to-parallel converter IC.
1.2 Keys
The front panel provides as much as ten keys including the programmable keys (S2, S3, S8, S9, S10
and S12), Up/Down key (S5, S11), Menu key (S4), Back key (S6), Power On/Off key (S1) and
Emergency key (S7).
A 3 row by 4 column matrix keyboard of the processor is used to identify operations of front panel keys.
Each of the 3 row signal lines are connected with the pull-up resistors R488, R499 and R511, and the 4
column lines are monitored to detect if a button has been pressed.
1.3 LCD Display
The TFT LCD can transfer data via the bus EMIFS of U302. Control signals include, write/read enable,
4
memory chip select, LCD chip select and reset signal, and the signals will be pulled up by R36, R35, R34,
R33 and R6 respectively. 5V voltage is converted to 3.3V by U5, and is then supplied to the LCD.
1.4 LED and Backlight
LED enable signal is fed to the serial-to-parallel converter IC, and then is output by U302. RX status is
indicated by green LED, and TX is by red LED. Backlight will be illuminated once any key is pressed.
The red and green LEDs in series are powered by 5V (U902) and controlled by Q2 and Q3. The
backlight is powered by 5V and controlled by Q1. Control signals are output via U1.
1.5 MMP Interfaces
The MMP interfaces are defined as follows:
No.
MMP10
1.6 Audio output
Definition & Description
Accessory identifier
1
port 1
2 PTT input
3
4 USB_D- USB data line D-
5 GND Ground
6 USB_VBUS Provides +5V for USB accessories.
7 Mic input
8 USB_D+ USB data +
9 HOOK Valid upon low level. The default is high level.
10
Handset audio
output
Accessory identifier
port 2
The pin together with pin 10 can form an accessory
identification matrix.
Used to input PTT signal from microphone. The pin is at
low level when PTT is hold down.
Used to output audio received from accessories; the
Handset option must be checked in the CPS.
Used to input external microphone signal. Vrms=80mV
@ 3K dev.
The pin together with pin 1 can form an accessory
identification matrix, details of which are stated in the file
“Definition of External Interfaces”.
Table 1 Definition of MMP Interfaces
The front panel provides two paths of audio output Handset_audio and SPK±. Handset_audio is the
output of received audio via MMP interface, and SPK± is the output by the PA U201 as audio signal for
the front panel speaker.
1.7 Volume Control
The encoder switch U7 will generate volume adjustment signals, which will be routed to U302 by
GPIO17 and GPIO18.
5
2. Working Principle of Baseband
Power System
Figure 2 Diagram of Power Distribution
Both the baseband control IC and the RF section can convert the supplied voltage to the appropriate
level via the voltage conversion IC.
z RF section: U914, Q920 and Q921 supply power for the RF section. High current PNP transistor
and comparator can function as LDO (Low Dropout Regulator).
z FGU: U918 and U915 supply 3.3V and 5V respectively to U100.
z Baseband: the processor U302 is supplied by 3.3V (U900), 1.8V (U903) and 1.6V (U919); the
memories are supplied by 3.3V (U900) and 1.8V (U903) respectively; the audio processor IC is
supplied by 3.3V (U900&U909) and 1.8V (U903); the DAC is supplied by 5V (U905) and 3.3V
(U900).
z EXT_SWB+: Q909.
2.1 Power On/Off
6
The mobile radio can be powered on/off through any of the following methods:
1) Power On/Off key
2) Ignition sense or Power On/Off key
3) Emergency
2.1.1 Power On/Off key
After the user presses the front panel Power On/Off key, R944 is grounded, and Q910 and Q905 are
turned on, causing the power management IC U902 and Q920 to start working. Then the processor
U302 will execute user routines, and can identify power on/off signals if low level is detected from Q914,
using the level PWR_CTRL to maintain or cut off the connection with the power system.
2.1.2 Ignition Signal
When voltage of ignition signal exceeds 7V, Q1 will be turned on through charging by C933, R955 and
R956, and the PNP transistor of Q905 will be further turned on to supply power. Q401 will also be turned
on. If signal is detected from Q401, U302 can identify ignition signals and then will generate the level
PWR_CTRL.
2.1.3 Emergency Alarm
When the emergency alarm pin is at low level, R940 is grounded, and Q906 is turned on to supply power.
Q908 is also turned on. When low level is detected from Q908 but the radio is powered off, U302 will
output the level PWR_CTRL and send emergency signal. If the radio is powered on then, U302 will only
output emergency signal.
2.1.4 Power-up Process
1) Turn on the radio through any of the methods mentioned above, and ensure enough time for
U900, U902, U903 and U919 to be turned on.
2) U917 will generate reset signal and remain low level for 1.25 seconds. Then the processor
starts to work.
3) Each method will generate and send a specific power-up signal to the processor.
4) After the signal is received, the processor will generate the level PWR_CTRL, and finish
power-up procedures.
2.2 Clock
7
Figure 3 Diagram of Clock Distribution
2.2.1 Input Clock
32K clock is used for timing and sleep of the whole system. Frequency of this clock is 32.768kHz, which
is subject to frequency division without error by U302 to finally get 1Hz, usually used for counting
seconds. Frequency of system clock is 19.2MHz, generated by external crystal oscillator.
2.2.2 Output Clock
The baseband outputs 3 clock signals fed to U231, U100 and Option board respectively.
2.3 Interface Distribution
2.3.1 SPI Interface
Figure 4 SPI Interface Block Diagram
SPI interface of the processor U302 can operate in master mode, controlled by MPU or DMA. In master
mode, U302 can provide 4 chip select signals, with CS2 used to enable IF processor U701. In master
mode, the maximum data transfer rate is as high as system clock frequency.
2.3.2 MCSI Interface
MCSI1.CLK
U302
MCSI1.DOUT
MSCI1.SYNC /CS
Figure 5 MCSI Interface Block Diagram
Dat
a
CLK
U100
During communication between U302 and U100, the former works in master mode with clock frequency
8
of up to 9.6MHz, and the latter uses MCSI frame synchronization as chip select signal. MCSI1.DOUT as
a data line is used to configure the memory U100.
2.3.3 MICROWIRE Interface
Figure 6 MICROWIRE Interface Block Diagram
The MICROWIRE interface can accommodate 4 external devices at most, and is generally used for
receiving control and status messages from external devices, and can also be used for reading data
from ROM. Its maximum clock frequency is a quarter of system clock frequency. MICROWIRE is used
for configuration of and reading from the audio processor, and requires chip select signal CS3.
2.3.4 SSI Interface
PCMCLK
PCMSYNC
PCMIN
PCMOUT
Option
Board
U231
BCLK
WCLK
SDIN
SDOUT
MCBSP3.CLKX
MCBSP3.FSX
MCBSP3.DX
MCBSP3.DR
MCBSP1.CLKX
MCBSP1.FSX
MCBSP1.DX
MCBSP1.DR
U302
CLKOUT
U701
U500
FS
DOUTA
SCLK
FS
DIN
/ LOAD
/PD
Figure 7 SSI Interface Block Diagram
U302 provides 3 McBSP interfaces McBSP1, McBSP2 and McBSP3, compatible with a variety of
interfaces. McBSP1 is connected with interface I2C of audio processor, to realize two-way transmission
of digital voice and data. McBSP2 uses independent clock and frame synchronization for transmitting
MCBSP2.CLKR
MCBSP2.FS
R
MCBSP2.DR
MCBSP2.CLKX
MCBSP2.FSX
MCBSP2.DX
GPIO29
GPIO31
and receiving. Interface SSI of the receiver processor is connected with RX end of McBSP2, and U500 is
9
connected with TX end of McBSP2. U302 works in master mode. McBSP3 is connected to the Option
Board interface for both voice and data transmission.
2.3.4 USB Interface
Figure 8 USB Interface Block Diagram
The radio has two USB interfaces, and both are connected to the USB signal port of the processor. REF
CLOCK is the reference frequency in specified mode. It should be 12MHz in high rate mode or 1.5MHz
in low rate mode.
2.3.5 UART Interface
Figure 9 UART Interface Block Diagram
U302 provides three UART interfaces, which enables the processor to communicate with a variety of
external devices. UART2 is used for communication with front panel and serial port on PC, and UART3
is used for communication with Option board and accessory jack (USB).
2.3.6 Further Development Port (MAP)
Further development port includes audio interface, programmable I/O, serial port, USB port, accessory
identifier port and etc, used for further development by the user. The pins are defined as follows:
Pin
Function Description
10
1 Vbus USB power supply
2 Ground
3 GP5_3 general purpose I/O port
(Chan_Act)
4 SW B+ sense power output 13V output voltage; output current ≤1.5A
5 External Alarm Programmable output pin (the default is External
6 Power Ground
7 Tx Audio input (audio from external
mic)
8 RX Audio output Used to output received audio signal.
9 Spkr- External speaker output -
10 USB D+ USB data +
11 USB_GROUDN Ground line
12 GP5_2 general purpose I/O port
(Monitor)
13 ACC_IO2 Accessory identifier port; three kinds of
14 Emergency switch
15 ACC_IO3 Accessory identifier port
16 PRGM_IN_PTT Programmable input pin (the default is PTT)
17 Audio Ground
18 Speaker + External speaker output +
19 USB D- USB data -
20 GP5_8 general purpose I/O port / serial
port RX
21 Ground
22 GP5_7 general purpose I/O interface /
serial port TX
23 GP5_6 general purpose I/O interface
24 AUX Audio Output 1 External speaker audio output 1
25 AUX Audio Output 2 External speaker audio output 2
26 Ignition sense Used to input ignition voltage
+5V power supply
General purpose I/O port with function defined
through the CPS
Alarm)
Used to input signal from external mic; audio
path is valid upon press of external PTT.
General purpose I/O port with function defined
through the CPS (the default is Monitor)
accessory identification status, and one default
status are provided by the pin together with pin
15 ACC_IO3.
When Emergency is active, this pin is at low
level.
valid upon low level
general purpose I/O interface
general purpose I/O interface
General purpose I/O interface with function
defined through the CPS
2.4 Audio Path
Table 2 Definition of Further Development Port
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