Gerber HS750 Plus User Manual page 72

plus
66 HS750
Phillips screws from the plotter right side plate, then slide the
cover straight off to the right.
5. Remove the keypad assembly (55) by taking out the two hex
lead screws from the right side plate.
6. On the large diagram, locate the theta motor (84) on the far
right closest to the front top of the plotter.
7. Find the pinion gear at the center of the motor, which meshes
with the theta gear and opto-disk assembly (49) on the rear
way shaft (45). Now locate the opto-sensing disk next to the
drive gear (49). It is a flat black disk about 1" in diameter.
8. Check to be sure that the disk is clean and centered between
the opto-sensors. These sensors are small black cubes
protruding from a small PC board (68).
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!
9. Turn the rear way shaft (45) by hand until the slot in the disk
faces straight up.
CAUTION: The keypad needs to be insulated from any
metal contact or it may short out.
10. Turn the machine on and watch the disk (49). It should rotate
and stop between the opto-sensors (located on 68)). If this
does not occur, call Gerber Field Service. Otherwise, continue
with the next step.
11. If the disk is clean and centered and homed correctly, loosen
the Allen set screw (48) but DO NOT MOVE THE DISK.
12. Turn the rear way shaft (45) until the locking pin (inside 101) is
moved to the 9:00 position.
If the disk is off-center, you must center the disk. To do so,
loosen the Allen set screw on the silver clamp next to the
disk (48). This allows the disk to be slid forward or
backward. When the disk is centered, tighten the Allen set
screw.
If the disk is dirty, shut off the plotter and the system.
Clean the disk with isopropyl alcohol using a lint free cloth
or a pipe cleaner, making sure all sides of the disk and
opto-sensors are clean.