IBM System/34 Maintenance Manual page 401

27-850 PICKER/CAM STEPPER MOTOR
CONTROL CARD SIGNAL
OUTPUT CHECK
1. Open the front left side cover.
2.
3.
4.
Loosen the two front safety shield screws and
remove the two rear safety shield screws and the
safety shield.
Set Power to I (operator panel).
Access the read/write head carriage to single step
the picker/cam stepper motor as follows: (Do not
access the read/write head carriage more than
one cylinder at a time.)
Set the Mode Selector switch to the Proc Run
position (CE panel).
Set the Address/Data switches to F800 (CE·
panel).
Set all CE panel switches to their down
position.
Press the Load switch (operator panel).
Select the exerciser option.
Select the diskette option.
Select the stepper motor step test option and
the read/write head carriage will move to
cylinder 40.
Install a jumper from THP-3 • (single step
picker) to THP-1
G
(ground).
Use the advance motor option of the stepper
motor test to single step the picker/cam
stepper motor.
DANGER
Parts of the driver board become hot after continuous
use.
116
Note: This procedure uses the read/write head carriage
circuits to move the picker/cam stepper motor.
Therefore, be careful to prevent damaging the
read/write head carriage control circuits as well as the
read/write carriage assembly.
5.
For the old style picker, probe test pin TPB-23
G
(- picker motor) for a down level.
For the new style picker, probe test pin TPB-22
G
(- picker motor) for a down level.
6. Probe test pins TPB-18
e,
19., 20
G,
and 21
e
(+auto step 0 through 3) for up levels (two lines
should be active at each step). Single step for this
check.
7. Remove the jumper.
8. Reinstall the safety shield using the four screws.
27-850
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