Motorola Control Head Manual

 Professional Radio
GM Series
Controlhead
Service Information
Issue: September 2000 

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in semiconductor memories or other media. Laws in the United States and other countries preserve for 
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 MODEL OVERVIEW
1.0 GM140/GM340/GM640 Models ........................................................................... 1-1
2.0 GM160/GM360/GM660 Models ........................................................................... 1-1
3.0 GM380/GM1280 Models ...................................................................................... 1-2
Chapter 2 THEORY OF OPERATION
1.0 Introduction...

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Chapter 3 TROUBLESHOOTING CHARTS
1.0 Troubleshooting Chart for Controlhead GM140/340/640 .................................... 3-1
1.1 On/Off ................................................................................................................. 3-1
1.2 Microprocessor ................................................................................................... 3-2
2.0 Troubleshooting Chart for Controlhead GM160/360/660 .................................... 3-3
2.1 On/Off...

Chapter 1
OVERVIEW
1.0 GM140/GM340/GM640 Models (GCN6112_)
The Controlhead contains the internal speaker, the on/off/volume knob, the microphone connector, 
several buttons to operate the radio and several indicator Light Emitting Diodes (LED) to inform the 
user about the radio status. To control the LED’s and to communicate with the host radio the control 
head uses the Motorola 68HC11E9 microprocessor.
2.0 GM160/GM360/GM660 Models 
(GCN6114-GM160 / GCN6120-GM360/660)
The Controlhead contains the...

1-2overview
3.0 GM380/GM1280 Models (GCN6121_)
The Controlhead contains the on/off/volume knob, the microphone connector, several buttons to 
operate the radio, several indicator Light Emitting Diodes (LED) to inform the user about the radio 
status, and a Liquid Crystal Display (LCD) with 21 pre - defined symbols and a 32*96 dot matrix for 
graphical or alpha - numerical information e.g. channel number, select code, call address name. To 
control the LED’s and the LCD, and to communicate with the host...

Chapter 2
THEORY OF OPERATION
1.0 Introduction
This Chapter provides a detailed theory of operation for the Controlhead circuits. For details of the 
trouble shooting refer to the related Section of this manual.
2.0 Controlhead Model for GM140, GM340 and GM640
The controlhead contains the internal speaker, the on/off/volume knob, the microphone connector, 
several buttons to operate the radio and several indicator Light Emitting Diodes (LED) to inform the 
user about the radio status. To control the...

2-2THEORY OF OPERATION
The microprocessor’s RAM is always powered to maintain parameters such as the last operating 
mode. This is achieved by maintaining 5V at µP  pin 25. Under normal conditions, when the radio is 
off, USW 5V is formed by FLT A+ running to D0822. C0822 allows the battery voltage to be 
disconnected for a couple of seconds without losing RAM parameters. Diode D0822 prevents radio 
circuitry from discharging this capacitor.
There are 8 analogue to digital converter ports (A/D) on the µP...

Controlhead Model for GM140, GM340 and GM640 2-3
An additional pair of analogue lines and A/D µP  ports (PE 3 – 2) is available to support a keypad 
microphone, connected to the microphone connector J0811. Any microphone key press is processed 
the same way as a key press on the controlhead.
2.6 Status LED and Back Light Circuit
All indicator LED’s (red, yellow, green) are driven by current sources. To change the LED status the 
host radio sends a data message via SBEP bus to the controlhead µP . The...

2-4THEORY OF OPERATION
2.8 Speaker
The controlhead contains a speaker for the receiver audio. The receiver audio signal from the 
differential audio output of the audio amplifier located on the radio’s controller is fed via connector 
J0801-10, 11 to the speaker connector P0801 pin 1 and pin 2. The speaker is connected to the 
speaker connector P0801. The controlhead speaker can be disconnected if an external speaker, 
connected on the accessory connector, is used.
2.9 Electrostatic Transient  Protection...