Ptx Removal; Ptx Replacement; Diskette Drive Control Card; Control Card Removal - IBM 3274 51C Maintenance Information

8. Install one end of a jumper,
G '
to pin A03 of the
PTXCP socket on the control card.
9. Observe the multimeter, and touch the other end of
the jumper several times to pin AOl of the PTXCP
socket on the control card. The multimeter should
read 2.5 Vdc or more when the test pin is touched.
(A wrong measurement can occur the first time the
test pin is touched.)
10. Power down.
11. Remove the jumper.
12. Reinstall the PTX connector on the control card.
13. Reconnect the drive motor power cable.
14. Power up.
E.3.6.6 PTX Removal
See Figure E-40
1 . Power down.
2. Remove the LED connector,
0 '
from the control
card. (Note the cable path for easier replacement.)
Pull the cable and the connector through the casting.
3. Turn the operator knob," ' to the closed position.
4. Loosen the lever screw,
G .
5. Push the bail,
CD,
inward slightly, and disconnect
the bail actuator cable eyelet,
0,
from the hook,
e,
on the bail lever,
e .
6. Turn the operator knob,
0 '
to the open position.
W,· :"'ly: Damage to the head
t
CD '
can occur if the pres-
sUle pad, . ' is permitted to hit the head.
7. Remove the four diskette guide mounting screws,
G.
8. Remove the diskette guide,
e,
by lifting it up and
carefully sliding the bail,
CD '
from under the head
load arm,
e.
9. Remove the five remaining connectors,
0 '
from
the control card. (Note the connector locations and
cable paths for easier replacement.)
10. Loosen the control card retainer screw,
e .
Warning: Be careful not to damage the control card.
11. Turn the two control card retainers,
Ci) ,
out of the
control card path, and remove the control card,
e.
(Note the position of the control card for easier
replacement.) .
12. Remove the PTX mounting screw,
0 '
and the PTX
assembly,
O.
(Note the cabie path for future
replacement.)
E.3.6.7 PTX Replacement
See Figure E-40.
1. Reinstall the PTX assembly,
0 '
and the PTX
mounting screw,
0 .
2. Reinstall the control card,
G,
and turn the two
retainers,
CD '
inward until they prevent the control
card from moving.
3. Tighten the two retainer screws,
G .
4. Reinstall the five connectors,
e '
on the control
card.
5. Reinstall the diskette guide,
G .
Place the bail
below the head load arm,
e .
6. Reinstall the four diskette guide mounting screws,
O.
7. Reinstall the LED connector,
Q '
on the control
card. Go to Bail Replacement (paragraph E.3.3.6,
step 2).
E.3.7 Diskette Drive Control Card
E.3.7.1 Control Card Removal
See Figure E-41.
1. Power down.
2. Remove the six connectors, " ' from the control
card.
3. Loosen the two retainer screws,
e '
and turn the
two retainers,
e '
outward until they are no longer
in the path of the control card,
G .
4. Remove the control card.
E.3.7.2 Control Card Replacement
See Figure E-41.
1. Reinstall the control card,
0 .
2. Turn the two retainers,
G '
inward slightly until
they prevent the card from moving.
3. Tighten the two retainer screws,
CD .
4. Reinstall the six connectors,
G '
on the control
card.
5. Power up.
E.3.7.3 Control Card Test Pins and Connector
Pins·
See Figure E-42.
Appendix E. IBM 31SD Diskette Drive Maintenance E-53