Chapter 2. Subsystem Problem Isolation Procedure; Step 1 Using The Isolation Procedure; Step 2 Power Test; Step 3 Bus Test - IBM 3274 51C Maintenance Information

Chapter 2. SubsysteJn Problem Isolation Procedure
The steps in the Subsystem Problem Isolation Procedure
must be performed in sequence. If you encounter a prob-
lem when performing these steps, you will be directed to
an FRU replacement figure (chart), a MAP, or a main-
tenance procedure. When the problem has been isolated
and repaired, the Machine Checkout MAP (AI 00) must
be used to verify correct operation.
Note: When servicing Models 5IC and 52C, observe the
applicable safety notices listed under "Safety Notices, " in
the front of the manual.
Step 1 - Using the Isolation Procedure
. a. Start with a completed Problem Report Form. Figure
2-1 shows a sample 3274 Problem Report Form.
Note: If the customer has not completed the fonn,
follow the 3274 PDG procedure before starting the
Subsystem Problem Isolation Procedure. Refer to the
Problem Report Form while following the Subsystem
Problem Isolation Procedure.
b. If a problem is encountered during installation or cus-
tomizing, or after installing a Miscellaneous Equipment
Specification (MES), go to MAP AlSO. Installation and
customizing cannot be considered completed until the
3274 has operated online successfully.
c. Follow this problem isolation flow sequentially until
you have fixed the problem, or use your support struc-
ture for aid if the problem is not corrected. Go to
the next step if the step you are performing does not
fix the problem or does not apply.
Note: If you are in a repetitive loop, request assistance
from the next level of the support structure.
d. The IML tests do not check the driver/receiver cards.
(Step 5 will assist you in isolation of a defective driver/
receiver card.) If this is a single-device failure, it is
assumed that the maintenance procedure for that
device has been performed.
Warning: For integrated modem multipoint attachment,
when the 3274 I/O telephone cable is unplugged, the
telephone socket must be terminated with 600-ohm
resistors. The 600-ohm terminating plug (shown in
Figure 5-11, Part 1 of 2) can be used.
e. See Chapter 5 for communication reference data,
Appendixes A through D for location drawings, power
information, board layouts, and cable drawings, and
Appendix E for 31 SD or Appendix F for 51 TO diskette
drive maintenance information.
f. Go to Machine Checkout MAP Al 00 after this fix. Go
to the next step if this step did not fix your problem or
does not apply.
Step 2 - Power Test
a. Check the OC On light: if it is off, go directly to Power
MAPAI20.
b. If all the operational indicators (8 4 2 1) are on:
(1) Check for loose cables in the operator panel assem-
bly. See Appendix D and Figure D-9.
(2) Replace the operator panel indicator card.
Step 3 - Bus Test
a. If the Bus Test fails, go directly to Bus Test MAP AID.
Note: A successful Bus Test is indicated if all the opera-
tional indicators
(8 4 2 1) are on while the IAfL pushbutton
is pressed and held, and ifall the indicators go offwlzen
IML is released.
Go to the next step if this step did not fix your problem
or does not apply.
Chapter 2. Subsystem Problem Isolation Procedure 2-1