Motorola Gm Controller Manual

 Professional Radio
GM Series
Controller 
Service Information
Issue: September 2000 

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Motorola certain exclusive rights for copyrighted computer programs, including the exclusive right to copy or 
reproduce in any form, the copyrighted computer program. Accordingly, any copyrighted Motorola computer 
programs contained in the Motorola products described...

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Table of Contents
Chapter 1 THEORY OF OPERATION
1.0 Controller Circuits ................................................................................................ 1-1
1.1 Overview......................................................................................................... 1-1
1.2 General ........................................................................................................... 1-1
1.3 Radio Power Distribution...

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Chapter 2 TROUBLESHOOTING CHARTS
1.0  Controller ............................................................................................................ 2-1
Chapter 3 CONTROLLER SCHEMATICS
1.0 Allocation of Schematics and Circuit Boards ....................................................... 3-1
2.0 T2 Controller  ....................................................................................................... 3-3
3.0 T5 Controller...

Chapter 1
THEORY OF OPERATION
1.0 Controller Circuits
1.1 Overview
This section provides a detailed theory of operation for the radio and its components. The main radio 
is a single board design, consisting of the transmitter, receiver, and controller circuits. The main 
board is designed to accept one additional option board. This may provide functions such as secure 
voice/data, voice storage or signalling decoder.
A controlhead is either mounted directly or connected by an extension cable. The...

1-2THEORY OF OPERATION
Figure 1-1 Controller Block Diagram
1.3 Radio Power Distribution
The DC power distribution throughout the radio board is shown in Figure 2-1. Voltage regulation for 
the controller is provided by 4 separate devices; U0651 (MC78M05) +5V, U0641 (LM2941) +9.3V, 
U0611 (LM2941) SWB+ limited to 16.5V and VSTBY 5V (a combination of R0621 and VR0621). An 
additional 5V regulator is located on the RF section.
The DC voltage applied to connector J0601 supplies power directly to the...

Controller Circuits1-3
The voltage VSTBY, which is derived  directly from the supply voltage by components R0621 and 
VR0621, is used to buffer the internal RAM. C0622 allows the battery voltage to be disconnected for 
a couple of seconds without losing RAM parameters. Dual diode D0621 prevents radio circuitry from 
discharging this capacitor.  When the supply voltage is applied to the radio, C0622 is charged via 
R0621 and D0621. To avoid that the µP enters the wrong mode when the radio is switched on...

1-4THEORY OF OPERATION
from emitter to collector of the pnp transistor. When the radio is turned on the voltage at the base of 
the npn transistor is pulled high and the pnp transistor  switches on (saturation). With voltage INT 
SWB+ now at supply voltage level, transistor Q0641 pulls pin 2 of the voltage regulators U0611 and 
U 0641 to ground level and thereby enables their outputs. 
The electronic on/off circuitry can be enabled by the microprocessor (through ASFIC CMP port 
GCB2, line DC POWER ON),...

Controller Circuits1-5
1.7 Ignition
Ignition sense is used to prevent the radio from draining the vehicle’s battery because the engine is 
not running. 
When the IGNITION input (J0501 pin 10) goes above 5 volts Q0661 is turned on via line IGNITION 
CONTROL. Q0661 turns on INT SW B+ and the voltage regulators by turning on Q0641 and the 
microprocessor starts execution. The microprocessor is alerted through line GP6 IN ACC10. The 
voltage at the IGNITION input turns Q0181 on, which pulls microprocessor...

1-6THEORY OF OPERATION
On the controller there are two ICs on the SPI BUS, ASFIC CMP (U0221-22), and EEPROM 
(U0111-5). In the RF sections there are 2 ICs on the SPI BUS, the FRAC-N Synthesizer, and the 
Power Control IC (PCIC). The SPI TRANSMIT DATA and CLK lines going to the RF section are 
filtered by L0481 / R0481 and L0482 / R0482 to minimize noise. The chip select line CSX from 
U0101 pin 2 is shared by the ASFIC CMP, FRAC-N Synthesizer and PCIC. Each of these IC‘s check 
the SPI data and when the...