IBM 3274 51C Maintenance Information page 95

4.15 Logic Board, Rel110val and Replacell1ent
(Figure 4-14)
l. Place the
fTl / L2J
(on/off) switch in the
l2J
position.
2. Remove the power cord plug from the building power
receptacle.
3. Remove all the cards from the board.
4. Disconnect the cables from the Y and Z rows.
5. Remove the 12 hex holding screws and retainers
0,
located on the wiring side.
Note:
Your board may haJ'e the /lew retainer
G.
6. Lift the board out (wiring side up).
7. Depending on the machine features, wire the replace-
ment board as follows:
a. If the 3274 is a Model 51C with board PN 5699828,
and control storage is equal to 64K (see Figure 2-4),
add a yellow wire from Q2G02 to Q2G12.
b. If the 3274 is a Model51C with board PN 5699828
and
does /lot
have the Type B Adapter feature cards,
add a yellow wire from E2G02 to E2B08.
Not Used
I/O Connector
Figure 4·14. Logic Board Assembly
c. If the 3274 contains the 1200-bps Integrated Modem
feature, perform the following:
• For a two-wire Nonswitched Network, add the
following yellow wires -
G2G02 to G2G09
G2J05 to G2J13
• For a Model 51 C with the card No. 14 Function
1200-bps Integrated Modem Card (Switched,
Auto Answer)
1200-bps Integrated Modem Card
(Nonswitched, Auto Answer SNBU)
Refer to Figure A-5 for part numbers and func-
tion; modify board wiring as shown below:
Board at
Remove Wire
Delete
Add Wires
Board PN EC Lovel From To Board Land
WirePN From To
EC 788931
5699828
G2B02 H5D12
EC 862637
EC 876269
5699828
G2B02 H5D12
EC 862635
5643329 EC 867313 G2B02 H5D12
6226635
No rework required
Diskette Drive
Not Used
FRONT
Ream R6B02
(on wiring
side) Doletlng
it from
R6C04 and
H5D12
- -
- -
- -
....
......
'0
I
I
I
I
I
I
I
"-
G2B02
R6B02
811695
H5012 R6C04
- - -- --
- - -- --
- -
-- --
.....
.....
....
Chapter 4. Removal and Replacement Procedures 4-15