IBM 3270 Maintenance Manual page 124

1.
Press 0 (RUN TESTS ONE TIME then press
Enter.
2. Press 1 (SYSTEM BOARD) then press Enter.
TESTING - SYSTEM BOARD
SYSTEM BOARD 100 S
DID THE TEST FINISH WITHOUT A lXX
ERROR MESSAGE?
NO Replace your system board (see Section 5,
"Removal/Replacement and Adjustments").
YES
Note: A 199 error message indicates you
answered "No" to the question about the
installed devices list. Do not replace the
system board. Refer to 3-9999-1,
"Undetermined Problem PIC," and verify
the installed devices.
Octol;>er 1984 3-100-3