Microprocessor - Motorola 6864115B62-C Detailed Service Manual

3-8 TROUBLESHOOTING 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
YES
NO
=5V ?
U0871
TP0866
Pin 73 EXTAL
NO
NO
= 8 MHz
= 0V
Check / Replace
Check / Replace
YES
YES
R0866 / C0866 /
R0873 / U0873 /
Q0866 / R0863
U0871
Check / Replace
R0861 / R0862 / D0861
1
C0861 / C0862 / U0861
C0863 / C0864 / C0865