Midland Syn-Tech III P25 User manual

Service Manual
Revised 4.24.2009
Part Number 680-100-2020
Complete Service Information
for
STP-105B VHF Portable
and
STP-404(A)(B) UHF Portable
SYN-TECH III P2
5
P
O
RTABLE RADI
O

SYN-TECH III P25 PORTABLE RADIO
SERVICE MANUAL
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OUR THANKS TO YOU
PREFACE
Thank you for purchasing the Midland Syn-Tech III P25 Portable Radio. Properly used, this product will
provide you many years of reliable service.
To get the most out of your purchase, be sure to carefully read this manual and keep it on hand for later
reference when needed.
Before servicing your radio, please read this entire manual.
CUSTOMER ASSISTANCE
If you require further assistance, please contact your local Midland dealer.
FOR WARRANTY, PRODUCT SERVICE AND ACCESSORY INFORMATION
Please contact your local Midland dealer or distributor.
Do not attempt to service any internal parts yourself.
This radio should be opened by authorized personnel only.
Otherwise, the warranty VOIDS.
Your radio is packed and labeled according to commercial packaging standards.
SYN-Tech III P25 Portable Radio is designed and manufactured for Midland Radio Corporation.
PATENT AND COPYRIGHT STATEMENTS
The AMBE+2™ voice coding Technology embodied in this product is protected by intellectual
property rights including patent rights, copyrights and trade secrets of Digital Voice Systems,
Inc. This voice coding Technology is licensed solely for use within this Communications
Equipment. The user of this Technology is explicitly prohibited from attempting to extract,
remove, decompile, reverse engineer of disassemble the Object Code, or in any other way
convert the Object Code into a human readable form. U.S. Patents Nos. #5,870,405,
#5,826,222, #5,754,974, #5,701,390, #5,715,365, #5,649.050, #5,630,011, #5,581,656,
#5,517,511, #5,491,772, #5,247,579, #5,226,084, and #5,195,166

SYN-TECH III P25 PORTABLE RADIO
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IMPORTANT SAFETY INFORMATION
GENERAL PRECAUTIONS
Use only MIDLAND authorized accessories. (Antennas, batteries, chargers, belt clips,
speaker/microphone sets, tactical headsets etc.).
Using unauthorized accessories may result in personal injury or cause damage to the
radio.
Charger is for indoor use only. Avoid direct sunlight and extreme heat sources. Use in a
dry cool place at max 40ºC.
CAUTION
Changes or modifications to radio may void its compliance with government laws/rules
and make it illegal to use.
Avoid using the radio at temperatures below -22ºF or above 140ºF.
Avoid storing the radio at temperatures below -40ºF or above 185ºF.
The charger is to be used for charging purposes only. It is not to be used during transmit.
Red light on the front of charger will change to green indicating the radio is fully charged.
For the initial charge, leave your radio in the charger for 4 to 6 hours.
WARNINGS
Your MIDLAND SYN-Tech III P25 Portable Radio generates electromagnetic RF energy
when transmitting. Ensure that you, and those around you, are not exposed to excessive
amounts of that energy (beyond recommended allowable limits for occupational use):
ALWAYS hold the radio, especially the antenna, at least 5 cm (2 inches) away from
yourself when transmitting.
WARNINGS ABOUT BATTERY
Do not place battery into fire.
Damaged battery may release dangerous chemical gasses. DO NOT breathe the fumes.
Misuse of battery may cause fire and/or explosion.
Do not disassemble battery pack. Battery cells contain electrolyte liquid which is damaging
to skin and clothes.
Do not short circuit + and – poles of battery pack. Short circuit between poles with metal
object may cause permanent damage to battery and may cause a fire.
Battery packs that have completed their life cycle must be disposed of properly.
If explosive gasses exist, do not remove or change battery. Movement of battery contacts
may cause spark, resulting in an explosion.

SYN-TECH III P25 PORTABLE RADIO
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NOTES
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SYN-TECH III P25 PORTABLE RADIO
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TABLE OF CONTENTS
1DEFINITIONS, ABBREVIATIONS AND ACRONYMS ............................................................................1-1
1.1 DEFINITIONS ................................................................................................................................... 1-1
1.2 ABBREVIATIONS AND ACRONYMS .............................................................................................. 1-1
2INTRODUCTION.......................................................................................................................................2-1
2.1 GENERAL FEATURES .................................................................................................................... 2-1
2.2 TECHNICAL SPECIFICATIONS ...................................................................................................... 2-2
3DESCRIPTION OF THE RADIO...............................................................................................................3-1
3.1 CONNECTION DIAGRAM................................................................................................................ 3-1
3.2 Operating Principles ......................................................................................................................... 3-2
3.2.1 RF and Control PCB..............................................................................................................3-2
3.2.2 Display and Keypad PCB ...................................................................................................... 3-4
3.2.3 DSP PCB............................................................................................................................... 3-4
4ADJUSTMENT..........................................................................................................................................4-1
4.1 DEFINITIONS AND ABBREVIATIONS ............................................................................................ 4-1
4.2 ADJUSTMENT CONDITIONS.......................................................................................................... 4-1
4.3 ADJUSTMENT SETUP..................................................................................................................... 4-1
4.4 ADJUSTMENT PROCEDURES ....................................................................................................... 4-3
4.4.1 RF Output Power Adjustment................................................................................................ 4-3
4.4.2 Analog Frequency Adjustment 25 kHz.................................................................................. 4-3
4.4.3 Digital Frequency Adjustment ............................................................................................... 4-3
4.4.4 Modulation Flatness Adjustment ........................................................................................... 4-3
4.4.5 Modulation Limiting Adjustment ............................................................................................ 4-4
4.4.6 FM Deviation Adjustment ...................................................................................................... 4-4
4.4.7 C4FM Deviation Adjustment.................................................................................................. 4-4
4.4.8 Squelch Adjustment............................................................................................................... 4-4
4.4.9 RSSI Adjustment ................................................................................................................... 4-5
4.4.10 C4FM Receive Level Adjustment .......................................................................................... 4-5
5TROUBLESHOOTING .............................................................................................................................5-1
6ILLUSTRATED PART LISTS...................................................................................................................6-1
6.1 SYN-TECH III P25 PORTABLE MAIN ASSEMBLIES...................................................................... 6-2
6.2 SYN-TECH III P25 PORTABLE RADIO PCB ASSEMBLIES........................................................... 6-4
6.3 SYN-TECH III P25 PORTABLE RADIO REAR PANEL ASSEMBLY............................................... 6-6
6.4 SYN-TECH III P25 PORTABLE RADIO FRONT PANEL ASSEMBLY ............................................ 6-8
6.5 SYN-TECH III P25 PORTABLE RADIO DISPLAY AND KEYPAD PCB ASSEMBLY....................6-10
6.6 SYN-TECH III P25 PORTABLE RADIO DSP PCB ASSEMBLY.................................................... 6-14
6.7 SYN-TECH III P25 PORTABLE RADIO VHF RF AND CONTROL PCB ASSEMBLY................... 6-17
6.8 SYN-TECH III P25 PORTABLE RADIO UHF RF AND CONTROL PCB ASSEMBLY...................6-24
7DISASSEMBLY AND ASSEMBLY..........................................................................................................7-1
7.1 REQUIRED EQUIPMENT ................................................................................................................ 7-1
7.2 USAGE ............................................................................................................................................. 7-2
7.3 DISASSEMBLING THE RADIO........................................................................................................7-2
7.4 DISASSEMBLING THE PCB ASSEMBLY ....................................................................................... 7-5
8SCHEMATIC DIAGRAMS........................................................................................................................8-1
8.1 RADIO CONNECTOR PINOUT........................................................................................................ 8-2
8.1.1 Side Control........................................................................................................................... 8-2
8.1.2 Audio Control......................................................................................................................... 8-2
8.1.3 External Accessory................................................................................................................ 8-2
8.2 VHF RF SCHEMATIC 136-174 MHz ................................................................................................ 8-3
8.3 UHF RF SCHEMATIC 380-470 MHz................................................................................................ 8-4

SYN-TECH III P25 PORTABLE RADIO
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8.4 UHF RF SCHEMATIC 450-512 MHz................................................................................................ 8-5
8.5 CONTROL SCHEMATIC .................................................................................................................. 8-6
8.6 DSP SCHEMATIC ............................................................................................................................ 8-7
8.7 LCD AND KEYPAD SCHEMATIC .................................................................................................... 8-8
FIGURES
Figure 3-1: Midland Syn-Tech III P25 Portable Radio Connection Diagram .................................................. 3-1
Figure 4-1: Adjustment Setup ......................................................................................................................... 4-2
Figure 6-1: Main Assemblies Location Diagram ............................................................................................. 6-2
Figure 6-2: PCB Assemblies Location Diagram.............................................................................................. 6-4
Figure 6-3: Rear Panel Assembly Location Diagram...................................................................................... 6-6
Figure 6-4: Front Panel Assembly Location Diagram ..................................................................................... 6-8
Figure 6-5: Display and Keypad PCB Location Diagram -1..........................................................................6-10
Figure 6-6: Display and Keypad PCB Location Diagram -2..........................................................................6-11
Figure 6-7: DSP PCB Location Diagram -1 .................................................................................................. 6-14
Figure 6-8: DSP PCB Location Diagram -2 .................................................................................................. 6-15
Figure 6-9: VHF RF and Control PCB Location Diagram -1 ......................................................................... 6-17
Figure 6-10: VHF RF and Control PCB Location Diagram -2 ....................................................................... 6-18
Figure 6-11: UHF RF and Control PCB Location Diagram -1....................................................................... 6-24
Figure 6-12: UHF RF and Control PCB Location Diagram -2....................................................................... 6-25
TABLES
Table 2-1: Syn-Tech III P25 Portable Radio General Specifications .............................................................. 2-2
Table 2-2: Batteries for Syn-Tech III P25 Portable Radios............................................................................. 2-2
Table 2-3: Syn-Tech III P25 Portable Radio Environmental Specifications.................................................... 2-2
Table 2-4: Syn-Tech III P25 Portable Radio Receiver Specifications ............................................................ 2-3
Table 2-5: Syn-Tech III P25 Portable Radio Transmitter Specifications ........................................................ 2-4
Table 3-1: KN1, RF and Control PCB to DSP PCB Signals ...........................................................................3-6
Table 3-2: KN2, RF and Control PCB to Display and Keypad PCB Signals .................................................. 3-7
Table 4-1: Spurious Signal Frequencies......................................................................................................... 4-1
Table 5-1: Syn-Tech III P25 Portable Radio Error Messages......................................................................... 5-1
Table 5-2: Syn-Tech III P25 Portable Radio Alert Messages ......................................................................... 5-2
Table 5-3: Syn-Tech III P25 Portable Radio ‘Problem-Solution’ Table........................................................... 5-3
Table 6-1: Main Assemblies Parts List............................................................................................................ 6-3
Table 6-2: PCB Assemblies Parts List ............................................................................................................ 6-5
Table 6-3: Rear Panel Assembly Parts List .................................................................................................... 6-7
Table 6-4: Front Panel Assembly Parts List.................................................................................................... 6-9
Table 6-5: Display and Keypad PCB Parts List ............................................................................................6-12
Table 6-6: DSP PCB Parts List .....................................................................................................................6-16
Table 6-7: VHF RF and Control PCB Assembly Parts List ...........................................................................6-19
Table 6-8: UHF RF and Control PCB Assembly Parts List...........................................................................6-26

SYN-TECH III P25 PORTABLE RADIO
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1 DEFINITIONS, ABBREVIATIONS AND ACRONYMS
1.1 DEFINITIONS
Channel :
The frequency or frequency pair which is used for transmission and/or
receiving of electrical or electromagnetic signals.
Channel Spacing : Distance between center frequencies of two neighboring channels.
Protocol :
Required rules sequence to be able to carry out a definite communication
function.
Site :
Location that contains one or more Repeater Radios, Assistant Units and
equipment groups that supply a determined coverage area. It has
connection to other Sites and/or Control Units.
Squelch :
TA radio circuit that mutes the loudspeaker when no valid transmitted signal
is detected.
1.2 ABBREVIATIONS AND ACRONYMS
A T:T Ampere
AES T:T Advanced Encryption Standard
APCO T:T The Association of Public-Safety Communications Officials
BER T:T Bit Error Rate
BPF T:T Band Pass Filter
C4FM T:T Continuous 4-Level Frequency Modulation
CD T:T Carrier Detect
CDCSS T:T Continuous Digital Coded Squelch System
CS T:T Chip Select
CTCSS T:T Continuous Tone Controlled Squelch System
dB T:T Decibel
dBm T:T Decibel Milliwatt
DC T:T Direct Current
DES T:T Data Encryption Standard
DSP T:T Digital Signal Processing
DSR T:T Data Set Ready
DTMF T:T Dual Tone Multi Frequency
DTR T:T Data Terminal Ready
EEPROM T:T Electrically Erasable Programmable Read Only Memory
EPROM T:TElectronically Programmable Read Only Memory
ESD T:T ElectroStatic Discharge

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FFSK T:T Fast Frequency Shift Keying
FM T:T Frequency Modulated
FPC T:T Flexible Printed Circuit
GPS T:T Global Positioning System
HPI T:T Host Port Interface
Hz T:T Hertz
IC T:T Integrated Circuit
IEC T:T International Electrotechnical Commission
IF T:T Intermediate Frequency
IMBE T:T Improved Multi-Band Excitation
kb/s T:T Kilobit per second
kg T:T Kilogram
LCD T:T Liquid Crystal Display
LNA T:T Low Noise Amplifier
LO T:T Local Oscillator
MCU T:T Microcontroller Unit
MHz T:T Mega Hertz
MIL-STD T:T Military Standards
mm T:T Millimeter
OFB T:T Output Feedback
PC T:T Personal Computer
PCB T:T Printed Circuit Board
ppm T:T Parts Per Million
RF T:T Radio Frequency
RSSI T:T Received Signal Strength Indicator
Rx T:T Receive
SINAD T:T SIgnal Noise And Distortion
SPI T:T Serial Peripheral Interface
TCXO T:T Temperature Controlled Crystal Oscillator
Tx T:T Transmit
UHF T:T Ulltra High Frequency
V T:T Volt
VCO T:T Voltage Controlled Oscillator

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VHC T:T Vehicular
VHF T:T Very High Frequency
VOGAD T:T Voice Operated Gain Adjusting Device
VSWR T:T Voltage Standing Wave Ratio
W T:T Watt
WACN T:TTT Wide Area Communication Network