IBM 3274 51C Maintenance Information page 29

Map A10 BUS TEST.
PAGE 1 OF 5
ENTRY POINTS
FROM ENTER THIS MAP
MAP ENTRY PAGE STEP
NUMBER
POINT NUMBER NUMBER
A20 A 001
001
(Entry Point A)
**********MAP SUMMARY**********
Maintenance concepts for Bus Test
This MAP uses card reference numbers to specify card socket
locations. See Fold Out (FO-3) to convert card number to the real
socket location.
Bus test tests the Control logic Bus for 'hot bits'(active lines on
the bus) when the IML switch is pressed and held. It also
functions as a lamp test for the four IML indicator lights on the
operators panel. This MAP will isolate a bus failure to one of the
following FRUs or card groups: Adapter cards, Control logic and
Adapter Control (Type A, B) cards, and the operator panel and
cable assembly. Bus test will run with only Control logic card (No.
g) and adapter control type A, card (No. 12) installed in the
machine.
CAUTION
Before removing cards or cables switch power off.
(Step 001 continues)
3-2
MAP A10-1
EXIT POINTS
EXIT THIS MAP
TO
PAGE STEP MAP ENTRY
NUMBER NUMBER
NUMBER POINT
2
005
A100 A
2 007
A100 A
3
008
A100
A
3
010 A100 A
3
012 A100 A
4
015
A100 A
4
017
A100 A
5
018 A100 A
5
020 A100 A
5
022
A100 A
5
023 A120 A
*A*
• Bus test has failed if any IML indicator is not on. A successful
Bus Test is indicated if all the operational indicators (8 4 2 1) are
on while the IML pushbutton is pressed and held, and all the
indicators go off when IML is released.
• If one or two IML indicators fails to light during bus test,
1. Replace card No. 12.
2. Replace the operators panel indicator card.
3. Verify for good cable continuity for -Led indicator on 1, 2, 4, 8
lines from board to operator panel card plug P2. See FO-7 or
FO-9.