Radio Shack PRO-197 Service Manual page 14

DSP Section (Digital Audio, etc.)
Receive a frequency with FM
mode, in tune mode. (Tune
okay on IC313-pin 2 (3.3 V), and
mode turns on digital
decode.)
Is voltage
IC313-pin 29 (1.8 V).
YES
Is receive
audio present on IC313
pin 19?
YES
Are square
waves on IC313 pins 4, 5,
6, and 28?
YES
Is digital
audio (voice) on IC313
pin 10 when recieving
IMBE?
YES
Defective IC313.
NO
Defective IC309, or LC305.
NO
Defective IC8, R339, C407
and/or associated circuit.
If IC313 pin 24 is high (3.3V),
NO
and pin 25 has a 10s of MHz
sine wave, defective IC313
and/or associated circuit.
Defective IC8, IC9, IC11,
speaker, and/or associated
NO
Also check that IC310 pin 27
goes low when receiving
IMBE, and IC307 pin 69 goes
high when receivng IMBE.
14
circuit.