Motorola Gm328 Gm338 Gm398 Detailed 6804112j18 E Manual

Controlhead Model for GM3982-9
4.0 Controlhead Model for GM398
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 LEDs and the LCD, and to communicate...

2-10Controlhead Model for GM398
If the radio was switched off, the radio’s µP will switch it on and vice versa. If the On/Off/Volume 
knob is pressed while the radio is on, the software detects a low state on line ON OFF SENSE, the 
radio is alerted via line ON OFF CONTROL and sends a data request message. The controlhead µP 
will inform the radio about the pressed knob and the radio’s µP will switch the radio off. If the radio is 
switched on either manually or automatically it’s +5V source switches on...

Controlhead Model for GM3982-11
When the controlhead µP wants to communicate to the host radio, the µP brings request line CH 
REQUEST to a logic “0” via µP pin 8. This switches on Q0852, which pulls line ON OFF CONTROL 
high through diode D0852. A low to high transition on this line informs the radio, that the controlhead 
requires service. The host radio then sends a data request message via BUS+ and the controlhead 
µP replies with the data it wanted to send. This data can be information like which...

2-12Controlhead Model for GM398
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 LEDs 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 LEDs.
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...

Controlhead Model for GM3982-13
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 informs the µP about the pressed PTT button. The µP will inform the host radio...

2-14Controlhead Model for GM398
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3-1
Section 3
TROUBLESHOOTING CHARTS
1.0 Controlhead GM328 Troubleshooting Flow Chart
1.1 On/Off 
Radio cannot 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
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 

3-2 Controlhead GM328 Troubleshooting Flow Chart
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 /...

Controlhead GM338 Troubleshooting Flow Chart 3-3
2.0 Controlhead GM338 Troubleshooting Flow Chart
2.1 On/Off 
Radio cannot 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 

3-4 Controlhead GM338 Troubleshooting Flow Chart
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 / 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 /...