Motorola Gm Series Detailed 6864115b62 B Manual

							Controlhead Model for GM380, and GM1280 2-11
output of the op-amp to rise and to reduce the base to emitter voltage of Q0943. This decreases the 
current of Q0941 until the loop has settled.
The back light for the LCD module uses a similar circuitry. The only differences are that µP port PH2 
controls the back light brightness and that the LED’s are located on the LCD module which is 
connected via J0821. Control line BL A GREEN connects to the anodes and control line BL K 
GREEN connects to the cathodes of the LED’s.
4.8 Liquid Crystal Display (LCD)
The LCD module consists of the display and the display driver and is connected via connector 
J0821. The display is a single layer super twist nematic (STN) LCD display. It has a dot matrix of 32 * 
96 dots for displaying graphics and alpha - numerical information and a line with 21 pre - defined 
icons above the dot matrix
The driver contains a data interface to the µP, an LCD segment driver, an LCD power circuit, an 
oscillator, data RAM and control logic. At power up the driver’s control logic is reset by a logic „0 via 
pin 5 of J0821. The driver’s µP interface is configured to accept 8 bit parallel data input (J0821-D0-
D7) from the controlhead µP (U0871 port PC0-PC7).
To write data to the driver’s RAM the µP sets chip select (J0821-6) to logic „0 via U0871-26, RD 
(J0821-10) to logic „1 via (U0871-40) and WR (U0821-9) to logic „0 via U0871-33. With input A0 
(J0821-8) set to logic „0 via U0871-34 the µP writes control data to the driver. Control data includes 
the RAM start address for the following display data. With input A0 set to logic „1 the µP then writes 
the display data to the display RAM. When data transfer is complete the µP terminates the chip 
select and the clock activities.
The display driver’s power circuit provides the voltage supply for the display. This circuit consists of a 
voltage multiplier, voltage regulator and a voltage follower. The regulator output voltage for the 
display can be controlled electronically by a control command sent to the driver. The voltage level 
can be measured by one of the µP’s analogue to digital converters (U0871-42) via J0821-21. To 
stabilize the display brightness over a large temperature range the µP measures the temperature via 
analogue to digital converter (U0871-43) using a temperature sensor on the module (J0821-4). 
Dependent on the measured temperature the µP adjusts the driver output voltage, and in turn the 
display brightness, via parallel interface.
4.9 Microphone Connector Signals
Signals BUS+, PTT IRDEC, HOOK, MIC, HANDSET AUDIO, FLT A+, +5V and 2 A/D converter 
inputs are available at the microphone connector J0811. Signal BUS+ (J0811-7) connects to the 
SBEP bus for communication with the CPS or the Universal Tuner. Line MIC (J0811-5) feeds the 
audio from the microphone to the radio’s controller via connector J0801-4. Line HANDSET AUDIO 
(J0811-8) feeds the receiver audio from the controller (J0801-6) to a connected handset. FLT A+, 
which is at supply voltage level, and +5V are used to supply any connected accessory like a 
microphone or a handset.
The 2 A/D converter inputs (J0811-9/10) are used for a microphone with keypad. A pressed key will 
change the dc voltage on both lines. The voltages depend on which key is pressed. The µP 
determines from the voltage on these lines which key is pressed and sends the information to the 
host radio.
Line PTT IRDEC (J0811-6) is used to key up the radio’s transmitter. While the PTT button on a 
connected microphone is released, line PTT IRDEC is pulled to +5 volts level by R0880. Transistor 
Q0871 is switched on and causes a low at µP port PA2. When the PTT button is pressed, signal PTT 
IRDEC is pulled to ground level. This switches off Q0871 and the resulting high level at µP port PA2  
						

							2-12THEORY OF OPERATION
informs the µP about the pressed PTT button. The µP will inform the host radio about any status 
change on the PTT IRDEC line via SBEP bus.
When line PTT IRDEC is connected to FLT A+ level, transistor Q0851 is switched on through diode 
VR0851 and thereby pulls the level on line ON OFF CONTROL to FLT A+ level. This switches on the 
radio and puts the radio’s µP in bootstrap mode. Bootstrap mode is used to load the firmware into 
the radio’s flash memory (See controller sub section for more details).
The HOOK input (J0811-3) is used to inform the µP when the microphone´s hang-up switch is 
engaged. Dependent on the CPS programming the µP may take actions like turning the audio PA on 
or off. While the hang up switch is open, line HOOK is pulled to +5 volts level by R0883. Transistor 
Q0872 is switched on and causes a low at µP port PA1. When the HOOK switch is closed, signal 
HOOK is pulled to ground level. This switches off R0883 and the resulting high level at µP port PA1 
informs the µP about the closed hang up switch. The µP will inform the host radio about any status 
change on the HOOK line via SBEP bus.
4.10 Speaker (Remote Mount Configuration only)
The remote mount 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 only an external 
speaker, connected on the accessory connector, should be used. If the controlhead is mounted 
directly on the radio, an external speaker is required.
4.11 Electrostatic Transient  Protection
Electrostatic transient protection is provided for the sensitive components in the controlhead by 
diodes VR0811 - VR0814. The diodes limit any transient voltages to tolerable levels. The associated 
capacitors provide Radio Frequency Interference (RFI) protection. 
						

							Chapter 3
TROUBLESHOOTING CHARTS
1.0 Controlhead GM140/340/640 Troubleshooting Chart
1.1 On/Off 
Radio can not be switched on via ON/OFF Volume 
NO
YES
YES
NO R0823 Pin TAB
= 5V ?
R0823 Pin TAB1
when pressed
= 5V ?Check / Replace 
Volume Pot R0823
Check / Replace
R0822 / VR0822 / 
D0822
NO
YES
J0801 Pin 2
> 10V ?Check / Replace
Q0821
Check / Replace
Q0822 / R0821
YES
NO
J0801 Pin 2
=5V ?Check / Replace
D0821 / R0852
Press and hold
On/Off Volume Knob 
						

							3-2TROUBLESHOOTING CHARTS
1.2 Microprocessor 
Power Up Alert Tone is OK but volume knob 
does not operate and no indicator is on
NO
YES
YES
NO
YES
NO
YES NO
YES
EXTAL
U0831 Pin 31
= 8.00 MHz ?
RESET
TP0833
= HIGH ?Check / Replace
C0833 / R0832 / U0831
Check radio controller Data Signal
on J0801 Pin 5
BUS+ ?
Data Signal 
on TP0836
SCI_RX ?
NO
Data Signal
on TP0837
SCI_TX ?
Check / Replace
R0831 / U0833 / U0831
Check / Replace
R0837 / R0836
Check / Replace
U0831
Check / Replace
D0831 / R0838
Measure with scope 
while rotating Volume  
						

							Controlhead GM160/360/660 Troubleshooting Flow Chart 3-3
2.0 Controlhead GM160/360/660 Troubleshooting Flow Chart
2.1 On/Off 
Radio can not be switched on via ON/OFF Volume Knob
NO
YES
YES
NO
R0823 Pin TAB
= 5V ?
R0823 Pin TAB1
when pressed
= 5V ?Check / Replace 
Volume Pot R0823Check / Replace
R0822 / VR0822 /
D0822 / C0822
NO
YESJ0801 Pin 2
> 10V ?Check / Replace
Q0821
Check / Replace
Q0822 / R0821
YES
NOJ0801 Pin 2
=5V ?Check / Replace
D0821 / R0852
Press and hold
On/Off Volume Knob 
						

							3-4TROUBLESHOOTING CHARTS
2.2 Microprocessor
Power Up Alert Tone is OK but volume knob does 
not operate and no indicator is on
NO
YES
YES
NO
YES
NO
YES NO
YES
EXTAL
U0831 Pin 31
= 8.00 MHz ?
RESET
TP0833
= HIGH ?Check / Replace
C0833 / R0832 / 
Check radio controller Data Signal
on J0801 Pin 5
BUS+ ?
Data Signal
on TP0836
SCI_RX ?
NO
Data Signal
on TP0837
SCI_TX ?
Check / Replace
R0831 / U0833 / U0831
Check / Replace
R0837 / R0836
Check / Replace
U0831
Check / Replace
D0831 / R0838
Measure with scope while 
rotating Volume Pot 
						

							Controlhead GM160/360/660 Troubleshooting Flow Chart 3-5
2.3 Display
Power Up Alert Tone is OK, volume knob does operate,
indicator/backlight is on but nothing on display
YES
NO
YES
NO
V5 (against 5V)
TP0973 between
-6V and -7V ?
Activity on
Address & Data lines
A0 / D0..D7 / CS1
of U0971?Check for shortage
U0831 / U0971
Check LCD Assembly
Check / Replace
C0971 / C0973 / R0972
R0973 / R0974 / U0971 
						

							3-6  TROUBLESHOOTING CHARTS
2.4  Backlight 
Power Up Alert Tone is OK, volume knob does operate,
YES
NO
Check for shortage
YES
NO
Check / Replace 
						

							Controlhead GM380/1280 Troubleshooting Flow Chart 3-7
3.0 Controlhead GM380/1280 Troubleshooting Flow Chart
3.1 On/Off 
R0854
Pin TAB1
when pressed
=5V ?
J0801 PIN2
> 10V ?
J0801 PIN2
 =5V?
Check / Replace
Q0853 / R0853
YES
NO
YES
NO
YES
NOCheck / Replace
D0852 / R0852
Check / Replace
Volume Pot R0854
Check / Replace
Q0851
Radio can not be switched on via ON/OFF Volume Knob
YES
R0854
Pin TAB
= 5V?NOCheck / Replace
R0855 / VR0855 / D0855
C0856
Press and hold
On / Off
Volume Knob 
						

							3-8TROUBLESHOOTING CHARTS
3.2 Microprocessor 
Power Up Alert Tone is audible on external speaker but volume
knob does not operate and no indicators are on
TP0876
=5V ?
NO YES
U0871
Pin 73 EXTAL
= 8 MHzTP0866
= 0V NO
Check / Replace
R0873 / U0873 /
U0871Check / Replace
R0866 / C0866 / 
Q0866 / R0863
Check / Replace
R0861 / R0862 / D0861
C0861 / C0862 / U0861
C0863 / C0864 / C0865 1
NO
YESYES