Head Load Solenoid And Bail; Solenoid And Bail Service Check - IBM 3274 51C Maintenance Information

6. Block the head/carriage about 25 mm (1 inch) from
the casting,
O.
7. Pull on the adapter welded to band
G
with
2.5 ± 0.25 pounds' force, and tighten the band clamp-
ing screw,
e.
Ensure that the band is parallel to
the pulley edge,
4D .
8. Move the carriage to track 00 and then to track 76.
Ensure that the band track is straight and that the
drive band is parallel to the pulley edge,
4D .
9. Carefully connect the head/carriage cable to the con-
trol card connector,
e.
10. Turn the stepper motor pulley,
G '
by hand to
track 40, and check with the timing pin,
0 .
Ensure that the pin goes into the casting.
I
DANGER
Voltage is still present at the socket when the
power cable is disconnected.
11. Disconnect the ac drive motor power cable,
0 .
12. Power up.
13. To disable the stepper motor, install a jumper,
0,
from TPC04 (ground) to TH05 (-'disable stepper
motor').
14. Install a jumper,
G '
from TPF01 (ground) to
TPH04 (MC-O).
15. Put the timing pin through the stepper motor pulley,
G,
into the timing hole in the casting. Does the
timing pin pass through the timing hole freely?
Y N
1
-
Remove the timing pin,
0 .
- Remove the jumpers ' " and
G.
Power down.
- Go to step 3 of paragraph E.3.2.3.
Remove the timing pin
0 .
16. Go to step 12 of paragraph E.3.2.3.
E-34
E.3.3 Head Load Solenoid and Bail
E.3.3.1 Solenoid and Bail Service Check
See Figure E-28.
1. Power down.
I DANGER
Voltage is still present at the socket when the
power cable is disconnected.
2. Disconnect the ac drive motor power cable,
CD .
3. Insert a diskette, and turn the operator knob,
e '
to the closed position.
4. Power up.
5. To activate the head load solenoid, install a jumper,
G '
from TPC04 (ground) to the head load TPH LD
(-'head load').
6. To deactivate the stepper motor, install a jumper,
G '
from TPC04 (ground) to TH05 (-'disable
stepper motor').
7. Verify a 0.3 to 0.7 mm (0.012 to 0.028 inch) gap, e '
between the bail and the head load arm at each
end of the head movement.
8. Is the gap
OK?
If not, go to Bail Adjustment (para-
graph E.3.3.4, step 5).
9. Remove the jumpers
G
and
O.
10. Turn the operator knob,
e,
to the open position,
and remove the diskette.
11. Turn the operator knob,
e '
to the closed position.
12. Power down.
13. Reconnect the ac drive motor power cable,
CD .
14. Power up.