Motorola GM950 User manual

Control Heads/Control Microphones Specific Information 4-i
Chapter 4
Control Heads/Control Microphones
Specific Information
Table of Contents
Table of Contents
Chapter Page
4A Control Head for Radio Model N2 ........................................................ 4A.1-i
4B Control Head for Radio Model N3......................................................... 4B.1-i
4C Hand Held Control Microphone GMN6151...........................................4C.1-i
4D Control Head for Radio Model N4.........................................................4D.1-i

Table of Contents
4-ii Control Heads/Control Microphones Specific Information

Hand Held Control Microphone GMN6151 4C-i
Chapter 4C
Hand Held Control Microphone GMN6151
Table of Contents
Table of Contents
Chapter
4C.1 Introduction/Theory of Operation
4C.2 PCB/Schematic Diagram and Parts List

Table of Contents
4C-ii Hand Held Control Microphone GMN6151

Introduction/Theory of Operation 4C.1-i
Chapter 4C.1
Introduction/Theory of Operation
Table of Contents
Table of Contents
Paragraph Page
1.0 Overview..................................................................................................... 1
2.0 Mechanical Parts List.................................................................................1
3.0 Theory of Operation .................................................................................. 2
3.1 General........................................................................................................ 2
3.2 Power Supplies............................................................................................ 2
3.3 Power On / Off............................................................................................. 2
3.4 PTT Button................................................................................................... 2
3.5 ON/OFF Hook Control................................................................................. 2
3.6 Keypad and Top Keys ................................................................................. 3
3.7 Switch Functions.......................................................................................... 3
3.8 Status LED and Back Light Circuit............................................................... 3
3.9 Liquid Crystal Display (LCD)........................................................................ 4
3.10 Microphone Amplifier................................................................................... 4
3.11 Speaker ........................................................................................................4
3.12 Connections to the Radio ............................................................................ 4
3.13 Electrostatic Transient Protection................................................................ 5
3.14 Jumper Functions........................................................................................ 5

Table of Contents
4C.1-ii Introduction/Theory of Operation

Overview
Introduction/Theory of Operation 4C.1-1
1.0 Overview
Hand Held Control Microphone GMN6151
The features of the Hand Held Control Microphone are as
follows:
■
■■On/Off Button
■
■■Rocker Type Volume Up/Down Control
■
■■Rocker Type Scroll Up/Down Control
■
■■3 digit, 7 segment Backlit LCD display
■
■■8 LCD Annunciators/Icons
■
■■3 LEDs (Red,Yellow, Green)
■
■■7 Dealer Programmable Option Buttons
2.0 Mechanical Parts List
GMN6151A Hand Held Control Mic
HLN9073B Hang-up Clip
AHN6050A HSG ASSY SPI
GLN7338A HH CONTROL MIC PCB
0102725B82 LCD GM950
7586044B02 Keypad code GM950
0102725B83 FRONT HSG
0102708D08 ASSY MIC
0102708D07 ASSY SPEAKER
3386016B03 Nameplate (GMN6151A)
5680918X03 CNT BOX
0102725B82 HHCM LCD GM950
1305844X01 Bezel LCD
2805397L10 Conn. Elastomer
3205157Y01 Gasket Lens
6105842X01 Lightpipe LCD
9105447Y01 Filter Display
5408344X01 40mm x 8 mm Label
7202698Y01 LCD GM950
AHN6050A HSG ASSY SPI HHCM
1105760Y01 Adhes.Cable Retainer
1505892Y01 Cover,rear
3005153Y06 Cable Coil
3205082E93 Gskt. O-Ring, main
4205158Y01 Retainer Cord
4205343Y01 Retainer
4C
.
1
GMN6151
(GM950)
0102725B83 HHCM FRONT HSG
1505891Y02 Housing
3305409X08 LLBL Nameplate
3505671Y01 Grillcloth
3805835X01 Button PTT
4505850X01 Lever PTT
7505618V02 Keypad PTT
0102708D08 ASSY MIC
3005637Y01 Cable Mic
5013920A01 Microphone Mini Elecret
0102708D07 ASSY SPEAKER
3005637Y01 Cable Mic
5005213W01 Speaker
7505581W02 Pad Speaker

Theory of Operation
4C.1-2 Introduction/Theory of Operation
3.0 Theory of Operation
3.1 General
The Control Microphone contains the speaker, the microphone, several buttons to operate the radio,
several indicator Light Emitting Diodes (LED) to inform the user about the radio status and a 3 digit /
7 segment Liquid Crystal Display (LCD) for nummerical information e.g. channel number, select
code.
3.2 Power Supplies
The power supply to the HHCM is taken from the host radio’s FLT A+ voltage via connector J0901
pin 8.This voltage is at battery level and is used for the voltage regulator (U0971), the LEDs, the
back light and to power up the radio via the On / Off button.The voltage regulator (U0971) provides
the stabilized 5 volt source for the display, the display driver, the shiftregister and the keypad buttons.
The regulated output of U0971 is enabled by a low state and disabled by a high state at pin 3 to
switch the HHCM circuits on and off. Input and output capacitors (C0972 and C0975, C0976) are
used to reduce high frequency noise and provide proper operation during battery transients.
3.3 Power On / Off
The On/Off button when pressed switches the radio’s voltage regulators on by pulling ON OFF
CONTROL to high via D0971 and connects the base of Q0971 to FLT A+.This transistor pulls the
line ANALOG 3 to low to inform the µP that the On/Off button is pressed. If the radio is switched off,
the µP will switch it on and vice versa.If the On/Off button is pressed and held while the radio is on,
the software detects a low state on line ANALOG 3 and switches the radio off.
While the radio is switched on, the radio’s controller enables the regulated output pin 1 of U0971 by
setting line LED CE to high and in turn pulling input U0971-3 to ground by transistor Q0972.Line
LED CE is also used to write data into the shiftregister U0983.After the serial write process line LED
CE is set to low for a few microseconds to update the output of the shiftregister with the new data.
The low - pass filtering provided by C0973 and R0974 filters out these small low periods and
prevents disabling of the voltage regulator output.
3.4 PTT Button
The PTT function is achieved by pressing button PB0901 which places a low on the PTT line to the
radio, causing the radio to transmit.
3.5 ON/OFF Hook Control
When the HHCM is off-hook the monitor input (line HOOK; J0901-9) to the radio is open circuit.
When the HHCM is placed on-hook the hang up clip shorts theTP0901 andTP0902 terminals which
takes the monitor input to ground, indicating to the radio that the microphone is on-hook.Diode
VR0922 and C0922, C0923 provide Electro Static Discharge (ESD) and Radio Frequency
Interference (RFI) protection.

Theory of Operation
Introduction/Theory of Operation 4C.1-3
3.6 Keypad andTop Keys
The HHCM keypad has 10 keys, plus 3 additional keys, the on/off key being one of them, which are
located on the top of the HHCM.
All keys are configured as 3 analogue lines (ANALOG 1 2 3) to the radio. Each of the lines controls
four keys; line ANALOG 3 additionally controls the on / off key.The voltage on the analogue lines
varies between 0V and +5V depending on which key has been pressed.If a button is pressed, it will
connect one of the 3 lines ANALOG 1,2,3 to a resistive voltage divider connected to +5V.The
voltages of these lines are A/D converted inside the µP and specify the pressed button.
3.7 Switch Functions
Ten of the switches (PB0931 - PB0934, PB0941 - PB0944, PB0953, PB0954) are the keypad
switches.The remaining 3 Top Key switches (PB0951, PB0952, PB0971) and the PTT switch
(PB0901) are simple contact closure switches.The switches and their functions are detailed below:
Switch Type Function
PB0901 Contact PTT
PB0931 Keypad Configurable
PB0932 Keypad Configurable
PB0933 Keypad Configurable
PB0934 Keypad Configurable
PB0941 Keypad Volume Down
PB0942 Keypad Volume Up
PB0943 Keypad Configurable
PB0944 Keypad Configurable
PB0951 Contact Configurable
PB0952 Contact Configurable
PB0953 Keypad Scroll Down
PB0954 Keypad Scroll Up
PB0971 Contact Power ON/OFF
3.8 Status LED and Back Light Circuit
All the indicator LEDs (3) and the back light LEDs (10) are driven by current sources Q0982 - Q0986
and controlled by the µP via SERIAL PERIPHERAL INTERFACE (SPI).The current is determined
by the resistor at the emitter of the respective current source transistor. Shiftregister U0983 stores
the LED status.To update the LED status line LED CLCK BUF shifts the data of line SPI DATA BUF
into the shiftregister.When all the data has been written, line LED CE is set to low for a few
microseconds to update the output of the shiftregister with the new data.
The green (D0983), red (D0982) and yellow (D0981) indicator LEDs are covered by the LCD display.
If a LED is switched on, the corresponding area of the LCD display is switched to transparent by the
respective shiftregister output using Exclusive-OR (XOR) gate U0982-1-4 and the backplane signal
from the LCD driver U0981 pin 26, 27.
The squarewave backplane signal from U0981 is buffered by XOR gate U0982-1 and then fed to one
of each inputs of the three remaining XOR gates.The output of these gates is the inverted
backplane signal, while the connected output of the shiftregister is high, and non-inverted while it is
low.The inverted backplane signal fed to the respective LCD input makes the corresponding area
transparent for the covered LED, while a non - inverted backplane signal makes it non-transparent.

Theory of Operation
4C.1-4 Introduction/Theory of Operation
3.9 Liquid Crystal Display (LCD)
The LCD display H0931 is a 3 digit / 7 segment display which incorporates 11 annunciators.Data is
loaded serially into the display driver U0932 via the SPI interface.The display data of line SPI DATA
BUF is shifted serially by clock signal LCD CLCK BUF.When the last bit has been received, the LCD
display is updated.
3.10 Microphone Amplifier
The microphone cartridge contains a capacitive transducer coupled to a FET amplifier.The
microphone’s audio signal is fed from the microphone inputs, MIC+ and MIC-, at J0903 to the
microphone amplifier.The microphone amplifier sets the frequency response and amplifies the
audio signal to the required radio input level (about 80mV at nominal sound pressure level).The first
stage (Q0902) connected to the microphone is an active high-pass filter which suppresses
frequency components below 300 Hz to prevent PL falsing in a receiving radio.The collector current
of Q0902, drawn from the collector of the following stage Q0901, is approximately 0.27 mA. A low-
pass filter composed of R0904 and C0907, C0908 filters out any audio frequency components riding
on this voltage.The output of the first stage is fed via R0906 to the second stage (Q0901) which
amplifies the audio signal to the radio’s input level.The supply voltage of the stage is provided by the
radio’s 9V3 voltage regulator via the load resistor (1kΩ) located on the radio’s controller section, line
MIC and connector J0901 pin 4. Q0901 draws a collector current of 2 mA.The collector AC current
of Q0901 causes a voltage drop across the load resistor representing the audio signal from the
microphone.
3.11 Speaker
The HHCM 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 lines INT SPKR+, INT
SPKR-, connector J0901-12,10 and parallel resistors R0921 - R0923 to the speaker connector
J0902 pin 1 and pin 2.The speaker is connected to the connector J0902. Resistors R0921 - R0923
reduce the audio power applied to the speaker to prevent overloading.
3.12 Connections to the Radio
Interconnections between the HHCM and the host radio are via an expanding cable which is
permanently connected to the HHCM.The cable has an 18 pin Molex connector which connects to
connector P0951 in the blank head of the host radio. P0951 is mounted on an adapter PCB. After
additional filtering the signals are fed to the host radio’s main PCB via connector J0950, also located
on the adapter PCB, a flexible ribbon cable and connector J0101.The connections between the
PCB in the HHCM and the main PCB in the radio are shown in the following table: