Table of Contents
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Chapters
Table of Contents
Related Manuals for Motorola GM950i
Summarization of Contents
Cautions and Warnings
Electrostatic Sensitive Devices (ESDs)
Precautions to minimize damage from electrostatic discharge to sensitive devices.
Safety Warnings
General Safety Warnings
Electrical power hazards, beryllium oxide components, and lead-acid battery handling precautions.
Service Manual Table of Contents
Introduction
Brief introduction to the manual and service policy.
Model Chart and Accessories
Lists available models and accessories for the mobile radio.
Maintenance
Disassembly, assembly, safety, testing, and diagnostics procedures.
Theory of Operation
Detailed description of radio operation, circuit reference.
Schematic Diagrams and Parts Lists
Component location diagrams, schematic diagrams, and parts lists.
216-246MHz Band Specific Information
Information specific to the 216-246MHz band split.
Appendix A: PL (CTCSS) Codes
List of PL codes and digital PL (DPL) codes for radio programming.
Appendix B: External Device Connectors
Details on accessory and microphone connector pin functions.
Appendix C: Radio Conversions
Instructions on altering the radio for base station operation.
Chapter 1: Introduction
Introduction Overview
Outlines the scope and use of the service manual and provides warranty/service support overview.
Scope of Manual
Specifies the manual's intended audience and content currency.
How to Use This Manual
Guides users on navigating and utilizing the manual's content effectively.
Warranty and Service Support
Details Motorola's support offerings for product exchange, repair, and spare parts.
Warranty Period Details
Explains warranty terms and conditions, including pre-shipment checks.
After Warranty Support Options
Describes Motorola's support services available after the warranty expires.
Technical Specifications for GM950E/GM950i
Provides detailed technical specifications for the radio models.
General Technical Specifications
Covers general specifications like frequency range, power supply, and dimensions.
Transmitter Specifications
Details transmitter parameters such as output power and modulation limiting.
Receiver Specifications
Lists receiver parameters including sensitivity, intermodulation, and selectivity.
Chapter 2: Model Chart and Accessories
Accessories Overview
Provides a summary of available accessories for the GM950E/GM950i mobile radio.
Model Chart
Lists different radio models with their specifications and corresponding part numbers.
Accessory Categories
Details various accessory types including hardware kits, microphones, and cables.
Mechanical Hardware Kits
Lists mechanical hardware kits for mounting and installation.
Microphones
Details available microphone options for the radio.
Speakers
Lists external speaker options and their specifications.
Cables
Details available cable types for the radio, including power and ignition cables.
Other Accessories
Lists miscellaneous accessories not categorized elsewhere.
Chapter 3: Maintenance
Maintenance Overview
Explains the chapter's content on disassembling/assembling the radio and test equipment.
Radio Disassembly Procedures
Step-by-step instructions for disassembling the radio to the transceiver board level.
Control Head Removal
Procedure for safely removing the control head from the radio transceiver.
Top Cover Removal
Instructions for removing the top cover of the radio chassis.
Transceiver Board Removal
Procedure for removing the transceiver board from the radio chassis.
Control Head Disassembly
Steps for disassembling the control head housing and its components.
Radio Assembly Procedures
Step-by-step instructions for reassembling the radio after maintenance.
Control Head Assembly
Procedure for assembling the control head with its components.
Transceiver Board Replacement
Instructions for installing or replacing the transceiver board.
Top Cover and Control Head Reassembly
Procedure for reattaching the top cover and control head to the radio.
Exploded View Diagrams and Parts Lists
Visual diagrams showing radio components and their corresponding parts lists.
Service Aids
Lists recommended service aids and tools required for radio maintenance.
Recommended Test Equipment
Lists standard and unique test equipment necessary for servicing the radio.
Radio Tuning Procedures
Detailed procedures for aligning and tuning the radio using the service software.
General Tuning Procedure Information
Describes the hardware and software setup for radio alignment procedures.
PA Bias Voltage Adjustment
Critical procedure for setting PA bias to ensure proper operation and prevent damage.
Battery Threshold Settings
Procedure for determining and setting battery threshold levels for radio operation.
Transmitter Power Adjustment
Procedure for setting transmitter power levels for customer applications.
Reference Oscillator Adjustment
Critical procedure for ensuring radio operation and preventing interference.
Front-End Pre-Selector Alignment
Procedure for aligning the pre-selector if receiver sensitivity is poor or parts are replaced.
Rated Volume Setting
Procedure for setting the rated volume at normal test modulation.
Squelch Adjustment
Procedure for setting the signal-to-noise ratio at which the squelch opens.
Transmit Deviation Limit Setting
Procedure for setting the maximum carrier deviation using low frequency.
Transmit Modulation Balance (Compensation)
Balances modulation sensitivity for proper signalling and waveform integrity.
Transmit Control Voltage Limit
Sets the maximum power control voltage for the transmitter.
Chapter 4: Theory of Operation
Theory of Operation Overview
Provides a detailed theory of operation for the radio and its components.
Controller Subsystem
Details the radio's controller, including digital control, audio processing, power, and voltage regulation.
Controller General Description
Describes the controller's main subsections and its closed architecture configuration.
Voltage Regulators for Controller
Explains the three voltage regulators providing power to the controller circuitry.
Electronic On/Off Circuitry
Describes the circuitry enabling software or external triggers to control radio power.
Mechanical On/Off Button
Explains the function of the physical on/off button on the control head.
Ignition Sense Function
Details how ignition sense prevents vehicle battery drain when the engine is off.
Microphone Hook Input
Describes the input used to inform the microprocessor about the microphone's hang-up switch status.
Microprocessor Clock Synthesizer
Explains how the controller generates and synthesizes the microprocessor clock frequency.
Serial Peripheral Interface (SPI) Operation
Details the µP's communication through the SPI port to various ICs.
SBEP Serial Interface for RSS Communication
Describes the serial interface used for radio communication with Radio Service Software.
General Purpose Input/Output (GP) Lines
Details the six general purpose lines available for interfacing with external options.
Normal Microprocessor Operation
Explains the microprocessor's internal memory and RAM power maintenance.
Control Head Model A2 or A3 Features
Describes the features and interface of the A2 and A3 control heads.
General Controller Board Operations
Covers general aspects of the controller board, including audio IC and ground.
Audio Filter IC (AFIC) Functionality
Explains the AFIC's role in RX/TX audio shaping, filtering, and amplification.
Audio Ground (VAG)
Describes the DC bias used as an audio ground for external op-amps.
Transmit Audio Circuits
Details the paths and processing of audio signals during transmission.
Microphone Input Path Description
Describes the internal and external microphone signal paths and biasing.
External Microphone Path
Explains how the external microphone signal enters the radio.
PTT Sensing and TX Audio Processing
Details how Push-To-Talk is sensed and how TX audio is processed.
Option Board Audio (GM950i)
Describes audio processing for option boards specifically in the GM950i model.
Transmit Signalling Circuits
Transmit Signalling Circuit Types
Details the types of signalling supported by the radio's hardware.
Sub-audible Data (PL/DPL) Generation
Explains how sub-audible data (PL/DPL) is generated and summed with voice.
Transmit Signalling Circuits
High Speed Data and DTMF Waveform Generation
Describes how high speed data and DTMF waveforms are created by the µP.
Receive Audio Circuits
Receive Audio Circuit Overview
Details the processing of received audio signals, including squelch and volume control.
Squelch Detect Functionality
Explains how the IF IC controls squelch characteristics and generates indicator signals.
Receive Audio Circuits
Audio Processing and Volume Control
Describes receiver audio path, filtering, de-emphasis, and programmable attenuation.
Audio Amplification and Speaker Output
Explains the audio PA stage, input level setting, and output to speakers.
Receive Audio Circuits
Handset Audio Interface
Describes the audio output for hand-held accessories with specific voltage level requirements.
Filtered Audio Path
Details the filtered audio path that bypasses the digital volume attenuator.
Discriminator Audio (Unfiltered)
Explains the routing of unfiltered discriminator audio from the IF IC.
Option Board Audio Interface
Describes how discriminator or filtered audio enters the option board for processing.
Receive Signalling Circuits
Receive Signalling Circuit Types
Details circuits for decoding sub-audible data and high-speed data signals.
Sub-audible Data Decoder (PL/DPL)
Explains how the microprocessor decodes sub-audible signals like PL and DPL tones.
High Speed Data Decoder Circuitry
Describes the circuitry for decoding high-speed data signals received by the radio.
Alert Tone Circuits Functionality
Explains how alert tones are generated and routed to the speaker for operator feedback.
UHF Receiver Front-End Description
Receiver Front-End Components (UHF)
Describes the receiver's front-end components for the UHF frequency range.
Front-End Band-Pass Filter and Pre-Amplifier (UHF)
Details the UHF band-pass filters and pre-amplifier for signal selection and gain.
Mixer and Intermediate Frequency (IF) Section (UHF)
Explains the mixer and IF stages for UHF signal conversion and processing.
Power Amplifier (PA) 5-25W Description
IF IC (U5201) Functionality
Describes the IF IC's role in signal amplification, filtering, demodulation, and squelch control.
Transmitter Power Amplifier (PA) 5-25W
Details the four-stage amplifier used to boost the radio's transmit level.
Power Controlled PA Stage Operation
Explains the first stage of the PA and its output power control mechanism.
Power Amplifier (PA) 5-25W Details
PA Stages Description
Describes the subsequent PA stages, including MOS FET and bipolar devices.
Directional Coupler Functionality
Explains how the directional coupler monitors forward RF power for control.
Antenna Switch Operation
Describes how the antenna switch operates synchronously with power control signals.
Power Amplifier (PA) 5-25W Control and Protection
Harmonic Filter Functionality
Details the harmonic filter's role in attenuating transmitter output energy.
Power Control Loop Operation
Explains the ALC loop for regulating transmitter power and protection features.
Frequency Synthesis Subsystem
Frequency Synthesis Components and Operation
Details the components and operation of the synthesizer subsystem.
Reference Oscillator Details
Describes the temperature-compensated crystal oscillator and its frequency setting.
Fractional-N Synthesizer (U3701) Functionality
Explains the features of the FRAC-N synthesizer IC for frequency generation and modulation.
Voltage Controlled Oscillator (VCO) Operation
Describes the VCO's role in frequency determination and modulation.
Synthesizer Operation Overview
Explains the overall operation of the synthesizer subsystem, including loop closure.
VHF Receiver Front-End Description
Receiver Front-End Components (VHF)
Describes the receiver front-end components for the VHF frequency range.
Front-End Band-Pass Filter and Pre-Amplifier (VHF)
Details the VHF band-pass filters and pre-amplifier for signal selection and gain.
VHF Mixer and Intermediate Frequency (IF) Section
Explains the mixer and IF stages for VHF signal conversion and processing.
Power Amplifier (PA) 5-25W Details
IF IC (U5201) Functionality
Describes the IF IC's role in signal amplification, filtering, demodulation, and squelch control.
Transmitter Power Amplifier (PA) 5-25W
Details the four-stage amplifier used to boost the radio's transmit level.
Power Controlled PA Stage Operation
Explains the first stage of the PA and its output power control mechanism.
Power Amplifier (PA) 5-25W Stages and Control
PA Stages Description
Describes the subsequent PA stages, including MOS FET and bipolar devices.
Directional Coupler Functionality
Explains how the directional coupler monitors forward RF power for control.
Antenna Switch Operation
Describes how the antenna switch operates synchronously with power control signals.
Power Amplifier (PA) 5-25W Filters and Control
Harmonic Filter Functionality
Details the harmonic filter's role in attenuating transmitter output energy.
Power Control Loop Operation
Explains the ALC loop for regulating transmitter power and protection features.
Frequency Synthesis Subsystem
Frequency Synthesis Components and Operation
Details the components and operation of the synthesizer subsystem.
Reference Oscillator Details
Describes the temperature-compensated crystal oscillator and its frequency setting.
Fractional-N Synthesizer (U3701) Functionality
Explains the features of the FRAC-N synthesizer IC for frequency generation and modulation.
Voltage Controlled Oscillator (VCO) Operation
Describes the VCO's role in frequency determination and modulation.
Synthesizer Operation Overview
Explains the overall operation of the synthesizer subsystem, including loop closure.
Chapter 5: Diagrams and Parts Lists
UHF Diagrams and Parts Lists Overview
Lists PCB layouts, schematic diagrams, and parts lists for UHF main board sections.
UHF Main Board Component Side Layout
Diagram showing component placement on the UHF main board's component side.
UHF Main Board Solder Side Layout
Diagram showing component placement on the UHF main board's solder side.
UHF GM950i Controller Schematic Diagram (Part 1)
Schematic diagram detailing the GM950i controller circuitry (first part).
UHF GM950i Controller Schematic Diagram (Part 2)
Schematic diagram detailing the GM950i controller circuitry (second part).
GM950i Controller Parts List
List of parts used in the GM950i controller schematic diagram.
UHF GM950E Controller Schematic Diagram (Part 1)
Schematic diagram detailing the GM950E controller circuitry (first part).
UHF GM950E Controller Schematic Diagram (Part 2)
Schematic diagram detailing the GM950E controller circuitry (second part).
GM950E Controller Parts List
List of parts used in the GM950E controller schematic diagram.
UHF Supply Voltage Schematic Diagram
Schematic diagram illustrating the supply voltage distribution and regulation circuits.
Supply Voltage Schematic Parts List
List of parts used in the supply voltage schematic diagram.
UHF Power Control Schematic Diagram
Schematic diagram detailing the power control circuitry for the transmitter.
Power Control Schematic Parts List
List of parts used in the power control schematic diagram.
UHF Power Amplifier 5-25W Schematic Diagram
Schematic diagram for the 5-25W power amplifier circuitry.
Power Amplifier Schematic Parts List
List of parts used in the power amplifier schematic diagram.
UHF Synthesizer Schematic Diagram
Schematic diagram detailing the frequency synthesizer circuitry.
Synthesizer Schematic Parts List
List of parts used in the synthesizer schematic diagram.
UHF Voltage Controlled Oscillator Schematic Diagram
Schematic diagram illustrating the voltage controlled oscillator circuitry.
Voltage Controlled Oscillator Schematic Parts List
List of parts used in the voltage controlled oscillator schematic diagram.
UHF RX-FE Schematic Diagram
Schematic diagram for the UHF Receiver Front-End circuitry.
RX-FE Schematic Parts List
List of parts used in the RX-FE schematic diagram.
UHF RX-IF Schematic Diagram
Schematic diagram detailing the UHF Receiver Intermediate Frequency circuitry.
RX-IF Schematic Parts List
List of parts used in the RX-IF schematic diagram.
Control Head Diagrams and Parts Lists
Diagrams and parts lists for the control head units.
Control Head Model K PCB Layout
Layout diagram for the Control Head Model K printed circuit board.
Control Head Model K Schematic Diagram
Schematic diagram for the Control Head Model K.
Control Head Model K Parts List
List of parts used in the Control Head Model K.
Control Head Model P PCB Layout
Layout diagram for the Control Head Model P printed circuit board.
Control Head Model P Schematic Diagram
Schematic diagram for the Control Head Model P.
Control Head Model P Parts List
List of parts used in the Control Head Model P.
Chapter 6.1: Model Chart and Technical Specifications
216-246MHz Models Overview
Provides an overview of the 216-246 MHz models available for the GM950i radio.
216-246MHz Model Chart
Lists GM950i models covering the 216-246 MHz frequency range.
216-246MHz Technical Specifications
Provides detailed technical specifications for the 216-246 MHz band radio.
General Technical Specifications (216-246MHz)
Covers general specifications for the 216-246 MHz band radio.
Transmitter Specifications (216-246MHz)
Details transmitter parameters for the 216-246 MHz band radio.
Receiver Specifications (216-246MHz)
Lists receiver parameters for the 216-246 MHz band radio.
Chapter 6.2: Radio Tuning Procedure
216-246 MHz Tuning Procedure Overview
Provides an overview of the radio tuning procedures for the 216-246 MHz band.
General Tuning Setup (216-246MHz)
Describes the recommended hardware and software for radio alignment.
PA Bias Voltage Adjustment (216-246MHz)
Critical procedure for setting PA bias for proper operation and to prevent damage.
Battery Threshold Settings (216-246MHz)
Procedure for setting battery threshold levels for radio operation.
Transmitter Power Adjustment (216-246MHz)
Procedure for setting transmitter power levels for customer applications.
Reference Oscillator Adjustment (216-246MHz)
Ensures radio operation and prevents interference by adjusting the reference oscillator.
Front-End Filter Alignment (216-246MHz)
Procedure for aligning the pre-selector if receiver sensitivity is poor or parts are replaced.
Rated Volume Setting (216-246MHz)
Procedure for setting the rated volume at normal test modulation.
Squelch Adjustment (216-246MHz)
Procedure for setting the signal-to-noise ratio at which the squelch opens.
Transmit Deviation Limit Setting (216-246MHz)
Procedure for setting maximum carrier deviation using low frequency.
Transmit Modulation Balance (Compensation) (216-246MHz)
Balances modulation sensitivity for proper signalling and waveform integrity.
Chapter 6.3: Theory of Operation
Theory of Operation Overview
Provides a detailed theory of operation for the radio and its components.
Controller Subsystem Description
Details the radio's controller, including digital control, audio processing, power, and voltage regulation.
Controller General Description
Describes the controller's main subsections and its closed architecture configuration.
Voltage Regulators for Controller
Explains the three voltage regulators providing power to the controller circuitry.
Electronic On/Off Circuitry
Describes the circuitry enabling software or external triggers to control radio power.
Mechanical On/Off Button Operation
Explains the function of the physical on/off button on the control head.
Ignition Sense Functionality
Details how ignition sense prevents vehicle battery drain when the engine is off.
Microphone Hook Input
Describes the input used to inform the microprocessor about the microphone's hang-up switch status.
Microprocessor Clock Synthesizer
Explains how the controller generates and synthesizes the microprocessor clock frequency.
Serial Peripheral Interface (SPI) Operation
Details the µP's communication through the SPI port to various ICs.
SBEP Serial Interface for RSS Communication
Describes the serial interface used for radio communication with Radio Service Software.
General Purpose Input/Output (GP) Lines
Details the six general purpose lines available for interfacing with external options.
Normal Microprocessor Operation
Explains the microprocessor's internal memory and RAM power maintenance.
Control Head Model A2 or A3 Features
Describes the features and interface of the A2 and A3 control heads.
General Controller Board Operations
Covers general aspects of the controller board, including audio IC and ground.
Audio Filter IC (AFIC) Functionality
Explains the AFIC's role in RX/TX audio shaping, filtering, and amplification.
Audio Ground (VAG)
Describes the DC bias used as an audio ground for external op-amps.
Transmit Audio Circuits
Details the paths and processing of audio signals during transmission.
Microphone Input Path Description
Describes the internal and external microphone signal paths and biasing.
External Microphone Path
Explains how the external microphone signal enters the radio.
PTT Sensing and TX Audio Processing
Details how Push-To-Talk is sensed and how TX audio is processed.
Option Board Audio (GM950i)
Describes audio processing for option boards specifically in the GM950i model.
Chapter 6.4 PCB/Schematic Diagrams and Parts Lists
216-246MHz Diagrams and Parts Lists Overview
Lists PCB layouts, schematic diagrams, and parts lists for the 216-246 MHz band radio.
216-246MHz Main Board Component Side Layout
Diagram showing component placement on the 216-246MHz main board's component side.
216-246MHz Main Board Solder Side Layout
Diagram showing component placement on the 216-246MHz main board's solder side.
216-246MHz 80ch Closed Controller Schematic Diagram (Part 1)
Schematic diagram for the 80ch closed controller (first part).
216-246MHz 80ch Closed Controller_IO Schematic Diagram (Part 2)
Schematic diagram for the 80ch closed controller's I/O (second part).
80ch Closed Controller Parts List
List of parts used in the 80ch closed controller schematic.
216-246MHz Supply Voltage Schematic Diagram
Schematic diagram illustrating the supply voltage distribution and regulation circuits.
Supply Voltage Schematic Parts List
List of parts used in the supply voltage schematic diagram.
216-246MHz Power Control Schematic Diagram
Schematic diagram detailing the power control circuitry for the transmitter.
Power Control Schematic Parts List
List of parts used in the power control schematic diagram.
216-246MHz Power Amplifier 5-25W Schematic Diagram
Schematic diagram for the 5-25W power amplifier circuitry.
Power Amplifier Schematic Parts List
List of parts used in the power amplifier schematic diagram.
216-246MHz Synthesizer Schematic Diagram
Schematic diagram detailing the frequency synthesizer circuitry.
Synthesizer Schematic Parts List
List of parts used in the synthesizer schematic diagram.
216-246MHz Voltage Controlled Oscillator Schematic Diagram
Schematic diagram illustrating the voltage controlled oscillator circuitry.
Voltage Controlled Oscillator Schematic Parts List
List of parts used in the voltage controlled oscillator schematic diagram.
216-246MHz RX-FE Schematic Diagram
Schematic diagram for the 216-246MHz Receiver Front-End circuitry.
RX-FE Schematic Parts List
List of parts used in the RX-FE schematic diagram.
216-246MHz RX-IF Schematic Diagram
Schematic diagram detailing the 216-246MHz Receiver Intermediate Frequency circuitry.
RX-IF Schematic Parts List
List of parts used in the RX-IF schematic diagram.
Appendix A: PL/DPL Codes
PL Codes and Digital PL (DPL) Codes
Lists PL and DPL codes for programming transmit or receive frequencies.
Self-Quieting Frequencies
Identifies frequencies that cause internal interference, affecting receiver sensitivity.
Appendix B: External Device Connectors
Accessory Connector Details
Details the pin functions of the 16-pin accessory connector for various radio models.
Microphone Connector
Describes the 8-pin Telco connector used for microphone and hook inputs.
Appendix C: Radio Conversions
How to alter the radio for Base Station Operation
Instructions for configuring the radio for base station operation by modifying components.
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