Motorola GM328

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 / R0838
Measure with scope while
rotating Volume Pot