Midland Syn-Tech III P25 Service Manual
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Midland Syn-Tech III P25 Service Manual

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Service Manual
Complete Service Information
for
STP-105B VHF Portable
and
STP-404(A)(B) UHF Portable
Revised 4.24.2009
Part Number 680-100-2020

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Summary of Contents for Midland Syn-Tech III P25

  • Page 1 Service Manual Complete Service Information STP-105B VHF Portable STP-404(A)(B) UHF Portable Revised 4.24.2009 Part Number 680-100-2020...
  • Page 3 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.
  • Page 4 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...
  • Page 5 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL NOTES...

  • Page 6: Table Of Contents

    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 DISASSEMBLY AND ASSEMBLY ......................
  • Page 7 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..................

  • Page 8: Definitions, Abbreviations And Acronyms

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL DEFINITIONS, ABBREVIATIONS AND ACRONYMS DEFINITIONS The frequency or frequency pair which is used for transmission and/or Channel receiving of electrical or electromagnetic signals. Distance between center frequencies of two neighboring channels. Channel Spacing...
  • Page 9 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL T : T Fast Frequency Shift Keying FFSK T : T Frequency Modulated T : T Flexible Printed Circuit T : T Global Positioning System T : T Host Port Interface T : T...
  • Page 10 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL T : T Vehicular T : T Very High Frequency T : T Voice Operated Gain Adjusting Device VOGAD T : T Voltage Standing Wave Ratio VSWR T : T Watt T : T T T...

  • Page 11: Introduction

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL INTRODUCTION GENERAL FEATURES Midland Syn-Tech III P25 portable radios have the following features: • 136-174 MHz VHF • 380-470 MHz UHF(A) • 450-512 MHz UHF(B) • Mixed analog and digital mode operation • Easy installation •...

  • Page 12: Technical Specifications

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL TECHNICAL SPECIFICATIONS Table 2-1: Syn-Tech III P25 Portable Radio General Specifications Modulation 16K0F3E, 11K0F3E, 11K0F1D, 11K0F2D, 11K0F1E Data Rate P25 : 9.6kb/s Symbol Rate P25 : 4.8kb/s Protocol Project 25-CAI : 4.4kb/s IMBE...

  • Page 13: Table 2-4: Syn-Tech Iii P25 Portable Radio Receiver Specifications

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 2-4: Syn-Tech III P25 Portable Radio Receiver Specifications 380-470MHz Frequency Range 136-174MHz 450-512MHz Frequency Separation Full Band split Channel Spacing 12.5 / 25 kHz Frequency Step 2.5 / 3.125kHz Rated Audio Output Power * 500mW / 8Ω...

  • Page 14: Table 2-5: Syn-Tech Iii P25 Portable Radio Transmitter Specifications

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 2-5: Syn-Tech III P25 Portable Radio Transmitter Specifications 380-470MHz Frequency Range 136-174MHz 450-512MHz Frequency Separation Full Band split Channel Spacing 12.5 / 25 kHz Frequency Step 2.5 / 3.125kHz Rated RF Output Power * 0.2–5 W...

  • Page 15: Description Of The Radio

    SERVICE MANUAL DESCRIPTION OF THE RADIO CONNECTION DIAGRAM Midland Syn-Tech III P25 Portable Radio Connection Diagram is given below. Figure 3-1: Midland Syn-Tech III P25 Portable Radio Connection Diagram ASSY FPCB HH PTT\SIDE KEYS, ASSY FPCB HH AUDIO POT\SEL KEYS and ASSY FPCB HH EXT ACCESSORY are parts of the ASSY FRONT PANEL STM Series P25 Portable MIDLAND (P/N: 5999-9037-2140).

  • Page 16: Operating Principles

    3.2.1 RF and Control PCB The RF and Control Board is designed to be used in Syn-Tech III P25 Portable Radio. It consists of Receiver Circuits, Transmitter Circuits, Voltage Controlled Oscillator Circuits, Frequency Synthesizer Circuits, Control Circuits and Audio Frequency Circuits. The board is supplied by 7.5 V voltage.
  • Page 17 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL receiver-transmitter switch and the 7 pole harmonic filter. Harmonics are suppressed more than 45 dB by the filter. The power control circuits monitor the current drawn by the driver and power amplifier by the voltage drop across R503 (R506).

  • Page 18: Display And Keypad Pcb

    3.2.2 Display and Keypad PCB The display and keypad board is the user interface for SYN-Tech III P25 Portable Radio. The radio is controlled by the On/Off-volume knob, channel switch and keypad, which are connected to the board by a flexible connection.
  • Page 19 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL The MCU communicates with DSP by means of the HPI-8 address and data registers. The HPI-8 data register in the DSP, includes bits controlling communication protocol. The HPI-8 communication substructure does not run when DSP is in reset mode. Unless the DSP clock is activated, it remains in the reset mode.

  • Page 20: Table 3-1: Kn1, Rf And Control Pcb To Dsp Pcb Signals

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 3-1: KN1, RF and Control PCB to DSP PCB Signals POSITION DEFINITION FUNCTION KN1-1 SSP_CE_WR Microprocessor WRITE signal KN1-2 BAT7V5 Unswitched, direct battery voltage KN1-3 DSP_CS Select microprocessor’s DSP data KN1-4 SW7V5...

  • Page 21: Table 3-2: Kn2, Rf And Control Pcb To Display And Keypad Pcb Signals

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 3-2: KN2, RF and Control PCB to Display and Keypad PCB Signals POSITION DEFINITION FUNCTION KN2-1 RS232_CTS RS232 CTS signal KN2-2 REG3V3 Regulated 3V3 voltage that supplies front panel KN2-3 RS232_RTS RS232 RTS signal...

  • Page 22: Adjustment

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ADJUSTMENT DEFINITIONS AND ABBREVIATIONS Additional definitions and abbreviations used are: : The lowest operating (user) frequency or adjacent channel : The highest operating (user) frequency or adjacent channel : (f )/2 or adjacent channel : Spurious Signal Frequencies;...

  • Page 23: Figure 4-1: Adjustment Setup

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Figure 4-1: Adjustment Setup...

  • Page 24: Adjustment Procedures

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ADJUSTMENT PROCEDURES Connect the equipment as illustrated. (Figure 4.1) Set the Power Supply output voltage to 7.5V and current limit to 2A. Set the RF Signal Generator output to its minimum level. Set the Audio Analyzer output impedance to 600Ω and amplitude to 0V Set the Modulation Analyzer to measure +/-peak deviation.

  • Page 25: Modulation Limiting Adjustment

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Repeat the steps ”c” and “d”. Select the medium test frequency. Set the audio signal frequency to 20Hz, click “MOD-2” and adjust MOD-2 parameter to obtain 0.0±0.05dB audio signal level on Audio Analyzer.

  • Page 26: Rssi Adjustment

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL 4.4.9 RSSI Adjustment Enter “RSSI Adjustment” window. Set the RF signal frequency to the test frequency without modulation. Set the RF signal level at the antenna input to the selected levels on RSSI Adjustment window and click “READ RSSI”.

  • Page 27: Troubleshooting

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL TROUBLESHOOTING Syn-Tech III P25 Portable Radio Error Messages are given in Table 5-1: Table 5-1: Syn-Tech III P25 Portable Radio Error Messages ERROR CAUSE SOLUTION MESSAGE ERROR 201 Is displayed when an error has been Change the RF &...

  • Page 28: Table 5-2: Syn-Tech Iii P25 Portable Radio Alert Messages

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Syn-Tech III P25 Portable Radio Alert Messages are given in Table 5-2: Table 5-2: Syn-Tech III P25 Portable Radio Alert Messages RADIO DISPLAY EXPLANATION Battery Messages If the battery voltage is below the first warning level, this message BATTERY LOW! appears once per minute.

  • Page 29: Table 5-3: Syn-Tech Iii P25 Portable Radio 'Problem-Solution' Table

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Syn-Tech III P25 Portable Radio ‘Problem-Solution’ Table is given in Table 5-3: Table 5-3: Syn-Tech III P25 Portable Radio ‘Problem-Solution’ Table PROBLEM POSSIBLE CAUSE(s) SOLUTION(s) No display on LCD when Battery is exhausted. Battery is not Recharge the battery.
  • Page 30 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL NOTES...

  • Page 31: Illustrated Part Lists

    MRA.exe program. (The Serial Port under the “Settings” Menu must be set to “data” to connect with your computer.) Syn-Tech III P25 Portable Radio Illustrated Parts Lists are given in this section. Please use part numbers for ordering.

  • Page 32: Syn-Tech Iii P25 Portable Main Assemblies

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE MAIN ASSEMBLIES Figure 6-1: Main Assemblies Location Diagram...

  • Page 33: Table 6-1: Main Assemblies Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-1: Main Assemblies Parts List ITEM NO DESCRIPTION ASSY FRONT PANEL HR 4700 BLACK MIDLAND 5999-9037-2140 ASSY REAR PANEL HR 4700 WITHOUT CIK 5999-9037-2112 ASSY PCB HR VHF RF AND CONTROL 136-174MHz 5999–9937-2111...

  • Page 34: Syn-Tech Iii P25 Portable Radio Pcb Assemblies

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO PCB ASSEMBLIES Figure 6-2: PCB Assemblies Location Diagram...

  • Page 35: Table 6-2: Pcb Assemblies Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-2: PCB Assemblies Parts List ITEM NO DESCRIPTION ASSY PCB HR VHF RF AND CONTROL 136-174MHz 5999–9937-2111 ASSY PCB HR UHF RF AND CONTROL 380-470MHz 5999-9937-2116 ASSY PCB HR UHF RF AND CONTROL 450-512MHz...

  • Page 36: Syn-Tech Iii P25 Portable Radio Rear Panel Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO REAR PANEL ASSEMBLY Figure 6-3: Rear Panel Assembly Location Diagram...

  • Page 37: Table 6-3: Rear Panel Assembly Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-3: Rear Panel Assembly Parts List ITEM NO DESCRIPTION BATTERY CONTACT SPL-04J-087 6160-3034-5001 ASSY LATCH SWI 4400 6030-0534-1004 BEARING Q4.7X2.80 6040-0534-1006 SCREW STLST/SOX M2X6 5307-1272-0206 O-RING SI Ø1.3x2.7x1.2 6008-0534-1004 WASHER THIN STLST/SOX 2X4.5X0.5...

  • Page 38: Syn-Tech Iii P25 Portable Radio Front Panel Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO FRONT PANEL ASSEMBLY Figure 6-4: Front Panel Assembly Location Diagram...

  • Page 39: Table 6-4: Front Panel Assembly Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-4: Front Panel Assembly Parts List ITEM NO DESCRIPTION PART NUMBER BAND LOUDSPEAKER 36 MM 6009-0534-1028 LOUDSPEAKER MYLAR M36A575-16BIP2J 5965-3090-0013 PORON 11X2 6009-0730-6004 CONN RECEPT SMA MODIFIED BHEAD 5936-3440-2270 WASHER D ANTENNA CONN 4400...

  • Page 40: Syn-Tech Iii P25 Portable Radio Display And Keypad Pcb Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO DISPLAY AND KEYPAD PCB ASSEMBLY Figure 6-5: Display and Keypad PCB Assembly Top Side 6-10...
  • Page 41 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Figure 6-6: Display and Keypad PCB Assembly Bottom Side 6-11...

  • Page 42: Table 6-5: Display And Keypad Pcb Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-5: Display and Keypad PCB Parts List ITEM DESCRIPTION ASSY PCB DISPLAY AND KEYPAD GN 5999-9937-2142 FRAME LCD HHR 4700 6040-4037-3034 CAP SER SMD 100P 5% 50V 0402 5910-0361-0116 C1, 7, 12, 24, 25, 28, 29, 46, 47, 48, 49, 50, 51, 52, 53,...
  • Page 43 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION RESISTOR TFMR SMD 0R 5% 0.063W 5905-4056-0000 SWITCH TACT SMD 5931-9989-9900 IC MAX7301AGL I/O QFN40 I 5961-5430-7301 IC OAM LMV321 SOT23-5 I 5961-5404-3210 TD3, 5 IC ASW SPDT SOT23-6 I 5962-5400-0001 AMPLIFIER 2X0.7W SSOP20 TDA8547I...

  • Page 44: Syn-Tech Iii P25 Portable Radio Dsp Pcb Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO DSP PCB ASSEMBLY Figure 6-7: DSP PCB Assembly bottom side 6-14...
  • Page 45 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Figure 6-8: DSP PCB Assembly Top Side 6-15...

  • Page 46: Table 6-6: Dsp Pcb Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-6: DSP PCB Parts List ITEM DESCRIPTION ASSY PCB DSP 5999-9937-2171 CAP X5R 1206 10U %10 10V 5910-0431-0060 KN2, 3 SOCKET 10P AXK5F10545J 5936-2401-0320 COIL POW SHI 220U 20-% 16(90) 5952-7000-9943 TE1, 2...

  • Page 47: Syn-Tech Iii P25 Portable Radio Vhf Rf And Control Pcb Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO VHF RF AND CONTROL PCB ASSEMBLY Figure 6-9: VHF RF and Control PCB Assembly Top Side 6-17...
  • Page 48 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Figure 6-10: VHF RF and Control PCB Assembly Bottom Side 6-18...

  • Page 49: Table 6-7: Vhf Rf And Control Pcb Assembly Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-7: VHF RF and Control PCB Assembly Parts List ITEM DESCRIPTION ASSY PCB VHF RF CONTROL 380-470MHZ 5999-9937-2111 BD1, 201, 202 FT BEAD 0402 SMD BK1005 5952-9900-0068 CAP X5R 0603 2U2 10% 6.3V...
  • Page 50 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION C325, 410 CAP COG 0402 50V 1% 39P 5910-0163-9120 C39, 40, 135, 310, 311, 404 CAP COG 0402 50V 1% 10P 5910-0161-0120 C4, 17, 24, 107, 210, 212, 324, 166 CAP COG 0402 50V 1% 47P...
  • Page 51 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION KN501 CONTACT SPRING ANTENNA IC 4400 6007-0534-1001 KN502 CONTACT SPRING ANTENNA DIS 4400 6007-0534-1002 SHEET AL NI 8X7X3 6040-0534-1001 KN8, 9 GASKET SMT 25SMT-3645-09 6015-0234-1003 KY1, 2, 3 SPRING CONTACT BMIC-001...
  • Page 52 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION R14, 122, 514, 515, 143, 144, 156, 157 RESISTOR TFMR SMD 220K 5% 0.063W 5905-4056-2204 R147 RESISTOR TFMR SMD 390K 5% 1/16W 5905-4056-3904 R148 RESISTOR TFMR SMD 1M 5% 0.063W 5905-4056-1005 R15, 303 RESISTOR TFMR SMD 220R 5% 0.063W...
  • Page 53 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION TD203 IC LVR TK112 SOT-23L C 5961-5430-1233 TD204, 501 IC OAM SOT23-5 IF 5961-5404-7111 IC FLS AT45DB161D-SU 8S2 I 5961-5134-5041 IC LVR MIC5206 SOT23-5 I 5961-5478-5206 TD401 IC AMP SGA-5486Z 5V SMD I...

  • Page 54: Syn-Tech Iii P25 Portable Radio Uhf Rf And Control Pcb Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SYN-TECH III P25 PORTABLE RADIO UHF RF AND CONTROL PCB ASSEMBLY Figure 6-11: UHF RF and Control PCB Assembly Top Side 6-24...
  • Page 55 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Figure 6-12: UHF RF and Control PCB Assembly Bottom Side 6-25...

  • Page 56: Table 6-8: Uhf Rf And Control Pcb Assembly Parts List

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Table 6-8: UHF RF and Control PCB Assembly Parts List ITEM DESCRIPTION ASSY PCB UHF RF CONTROL 380-470MHZ 5999-9937-2116 BD1, 201, 202 FERRITE BEAD 0402 SMD BK1005 5952-9900-0068 CAP X5R 0603 2U2 %10 6.3V...
  • Page 57 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION C501, 516 CAP COG 0603 8.2P 100V %5 5910-0388-2131 C502 CAP COG 0603 6.8P 100V %5 5910-0386-8131 C503, 507 CAP COG 0603 1.8P 100V %5 5910-0381-8131 C504 CAP NPO %5 150P SMD ATC700A...
  • Page 58 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION L106, 107 COIL HVA SMD 0906-5GLC %2 5952-0905-9901 L108 COIL RF SMD 0805 15N %5 5952-7309-1501 L109 COIL RF SMD 0805 22N %5 5952-7309-2201 L110 COIL RF CHIP 0805 56N %5...
  • Page 59 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION R27, 35, 45, 140, 218 RESISTOR KFMR SMD 4K7 %5 1/16W 5905-4056-4702 R301, 316, 406, 510 RESISTOR KFMR SMD 5R6 %5 1/16W 5905-4056-5608 R311, 405 RESISTOR KFMR SMD 56R %5 0.063W...
  • Page 60 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL ITEM DESCRIPTION TR102 TR NPN SMD 9GHZ BFG540W I 5961-5730-5400 TR103 TR JFN VHF BF512 SOT23 5961-5523-0512 TR104 TR NPN UHF BFR93AW SOT323 5961-5523-1934 TR MOSFET P-CHANNEL TSOP6 I 5961-5730-3443 TR301, 302, 401...

  • Page 61: Disassembly And Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL DISASSEMBLY AND REASSEMBLY WARNING Electro Static Discharge (ESD) * TO FEEL -3500V or higher *TO HEAR -4500 V or higher, *TO SEE SPARK -5000V or higher is necessary. This equipment has ESD sensitive parts; hence the following precautions are necessary during disassembly and assembly.

  • Page 62: Usage

    The parts location diagrams in the parts lists may help with the disassembly/reassembly procedure. DISASSEMBLING THE RADIO The Syn-Tech III P25 Portable Radio consists of a front panel, rear panel and accessory boards between them. The radio is secured together by screws and washers accessible in rear panel assembly. The...
  • Page 63 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL The connection of the accessory boards to the front panel is made by three flexible ribbon cables. The flexible ribbon cables are attached to three connectors on the front panel. These connectors should be opened to disconnect the ribbon cables.
  • Page 64 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL As shown in the picture below, flexible circuits are separated from the connectors using tweezers. There is a connection point on the main board that connects the RF and Control Board to the antenna connector. This part must make contact with the antenna connector (in the front panel) during assembly as shown below.

  • Page 65: Disassembling The Pcb Assembly

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL DISASSEMBLING THE PCB ASSEMBLY The PCB assembly is secured together with the screws and washers described below. DESCRIPTIONS SCREW STL ST M1.6X8 5307-1206-9408 WASHER SPRING STL ST 1.8X3.4X0.25 6005-0534-1001 The screws and washers are removed from the PCB assembly as shown below.
  • Page 66 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL Pictures and part numbers of the PCBs are given below. They are listed according to the disassembly order. Disassemble the Display and Keypad Board (P/N: 5999-9937-2142) Disassemble the spacer (P/N: 6003-4037-2002) Disassemble the RF and Control Board (136-...
  • Page 67 SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL The RF and Control Board are separated from the RF shields to access the DSP Board. The DSP Board is separated from RF and Control Board by using tweezers to lift it. Separated view of the two boards is shown below.

  • Page 68: Schematic Diagrams

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL SCHEMATIC DIAGRAMS Page RADIO CONNECTOR PINOUT 8.1.1 Side control 8.1.2 Audio Control 8.1.3 External Accessory VHF RF SCHEMATIC 136-174 MHz UHF RF SCHEMATIC 380-470 MHz UHF RF SCHEMATIC 450-512 MHz CONTROL SCHEMATIC DSP SCHEMATIC...

  • Page 69: Radio Connector Pinout

    SYN-TECH III P25 PORTABLE RADIO SERVICE MANUAL RADIO CONNECTOR PINOUT 8.1.1 Side Control 8.1.2 Audio Control 8.1.3 External Accessory...
  • Page 70 KILITSIZ : 3V -10dBm RX ON : 3.3V RX OFF : 0V TX ON : 3.3V 1Vpp TCXO KAPALI : 0V TX OFF : 0V TCXO ACIK 3.3V 1.5V MIDLAND RADIO CORPORATION SYN-TECH III VHF PORTABLE RF SCHEMATIC 136-174 MHz aselsan...
  • Page 71 GND1 VOUT C223 C225 C224 4u7 10V 100p 100n 10V DRAWING REV. GECERLILIK TR. MENTOR MIDLAND RADIO CORPORATION RESMI TANIM/DESCRIPTION DOKUMAN NO./DOCUMENT NO. REV. EFECTIVITY DT. ASSY PCB HH RF AND CONTROL 5999-9937-2116 SYN-TECHIII UHF PORTABLE 380-470 MHz YENILENEN T.SF.
  • Page 72 Schematic not available at this printing MIDLAND RADIO CORPORATION SYN-TECH III UHF PORTABLE RF SCHEMATIC 450-512 MHz...

  • Page 73: Control Schematic

    MIDLAND RADIO CORPORATION SYN-TECH III PORTABLE CONTROL SCHEMATIC aselsan...

  • Page 74: Dsp Schematic

    MIDLAND RADIO CORPORATION SYN-TECH III PORTABLE DSP SCHEMATIC...

  • Page 75: Lcd And Keypad Schematic

    MIDLAND RADIO CORPORATION SYN-TECH III PORTABLE LCD AND KEYPAD SCHEMATIC aselsan...
  • Page 77 5900 PARRETTA DRIVE, KANSAS CITY, MISSOURI, 64120 PHONE: (816) 241-8500, FAX: (816) 241-5713 www.midlandradio.com...

This manual is also suitable for:

Stp-105bStp-404aStp-404b

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