Radio Shack PRO-2050 Service Manual page 12

Microprocessor Check
Defective
R252-R271 and/or
key contact.
YES
IC201 is OK.
NO
NO
Defective IC206.
NO
Defective X201 and/or
associated circuit of IC201.
NO
Defective L201.
NO
Defective R206
and/or IC202.
NO
Defective R204, R205, R216, R217 and/or IC202.
Note: While checking the above items, the microprocessor might "loek up."
If so, turn the power switch OFF and then ON and restart to check.
-12-