Radio Shack PRO-197 Service Manual page 12

Microprocessor Check
NO
Defective key contact or
CPU Pin 47-52, Pin 55-
59, Pin 61.
Power ON.
Does the display
work properly?
YES
Does the key entry
work properly?
YES
IC307 is OK.
NO
Does
3.3 volts exist at IC307
pin 14 and 60?
YES
Does 3.3 volts exist
at IC307 pin 17.
YES
Is the clock
oscillation normal at pin
11 of IC307?
YES
Defective IC307, LCD
and/or associated
circuit.
12
NO
Defective IC12
and/or associated
circuit.
NO
Defective IC303
and/or associated
circuits.
NO
Defective X301 and/
or associated
circuits of IC307.