Radio Shack PRO-197 - Page 12

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