Motorola Control Head Manual

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...

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 

3-6TROUBLESHOOTING CHARTS
2.4  Backlight 
Power Up Alert Tone is OK, volume knob does operate,
indicator/display is on but no backlight
NO
YES
YES
NO
U0831 Pin 58
is toggling ?
Base of Q0934
> 0.7V ? Check / Replace 
R0847 / C0843 / R0943
Check for shortage U0831
YES
NO
Collector of
Q0934
>5V and < 11V ? Check / ReplaceQ0934 U0931 /R0941 / 
R0942 / R0944 / R0945
Check / Replace
Q0933 / R0947 / R0948 

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 

Controlhead GM380/1280 Troubleshooting Flow Chart 3-9
3.3 Microprocessor 
1
Data Signal
on J0801
Pin 5 BUS+
?
Data Signal
on TP0877
SCI_RX
?
Data Signal
on TP0878
SCI_TX
 ?
Check / Replace
D0872 / R0887
YES
YES
YES
NO
NO
NOCheck / Replace
U0871
Check 
Radio Controller
Check / Replace
R0888 / R0889
Measure with scope
while rotating
Volume Pot 

3-10TROUBLESHOOTING CHARTS
3.4 Display 
TP0973
Voltage Sense
between
 2V and 2.4V
?
Activity on
Address & Data lines
A0 / D0...D7 / CS1
of U0971
?
NO
YES
YES
NO
Check / Replace
Flex connection
Resistors on Address & Data
lines and LCD Module
Check / Replace 
LCD Module
Check for shortage
U0871
Power Up Alert Tone is audible, volume knob does operate,
indicator/backlight is on but nothing is seen on the display. 

Controlhead GM380/1280 Troubleshooting Flow Chart 3-11
3.5 Keypad Backlight 
U0871 Pin 25
is toggling ?
Base of Q0943
> 0.7V ?
Collector of
Q0943
>5V & < 11V
 ?
Check / Replace
Q0941 / R0955 / R0957
YES
YES
YES
NO
NO
NO
Check / Replace
Q0943 / U0941 / R0941
R0943 / R0949 / R0951
Check for shortage 
U0871
Check / Replace
R0945 / C0943 / R0947
Power Up Alert Tone is audible, volume knob does operate,
display is on but no keypad backlight. 

3-12TROUBLESHOOTING CHARTS
3.6 Display Backlight 
U0871 Pin 24
is toggling ?
Base of Q0963
> 0.7V ?
Collector of
Q0963
>5V & < 11V
 ?
Check / Replace
Q0961 / R0975 / R0977
YES
YES
YES
NO
NO
NO
Check / Replace
Q0963 / U0941 / R0961
R0963 / R0969 / R0971
Check for shortage 
U0871
Check / Replace
R0965 / C0963 / R0967
Power Up Alert Tone is audible, volume knob does operate,
display is on but no display backlight.