Tektronix Phaser 840, Service Manual

Page: 111 / 207

100 Phaser 840 and 850 Color Printers
Y-axis belts tension adjustment (Phaser 850 printer)
Perform this procedure after loosening or removing the Y-axis belt drive
assembly. Note the additional steps you must perform for a new Y-axis drive
assembly.
Warning It is not necessary to remove the tensioning bracket for this
adjustment. However, if you do, follow the procedure “Y-axis belt
drive assembly (Phaser 850 printer)” on page 147. Improperly
removing the tension spring can cause the tension bracket to flip
off forcefully, causing injury.
1.
Ensure that the three mounting screws that secure the Y-axis drive
assembly to the chassis are 1 turn loose and that the Y-axis drive
assembly slides freely with respect to the chassis.
Note
If there is a situation in which diagnostics are not available when
installing a new Y-axis drive assembly or drum/transfix
assembly, then locate any previously placed index marks on the
pulleys and proceed as if re-using existing parts. Allow the system
to cool as long as feasible before mounting the Y-axis drive
assembly onto the chassis. Tensioning of the y-axis drive assembly
without diagnostics increases the risk of failures associated with
low belt tension (for example, a “growling” sound heard upon
cold power-ups).
2.
If not in place, attach the tension spring between the Y-axis drive
assembly and the tension spring bracket. Note that a metal clip attaches
the spring to the Y-axis drive assembly; the spring DOES NOT attach directly
to the plastic housing of the Y-axis drive assembly. Refer to the illustration
on page 147.
3.
While the belts are under tension, rotate the drum pulley 5 times to
rotate the belts and seat them in place. For an old Y-axis drive assembly,
continue rotating the pulleys until the index marks on each pulley align
next to each other.
4.
Beginning with the upper-right screw, tighten the three mounting
screws to 30 in.-lbs. to secure the Y-axis drive assembly in place.
5.
For new Y-axis drive assembly. Using PC-based diagnostics, run the
test: “Position for Belt Tightening” in the “Y-Axis Group” test suite.
This positions the belts in the proper orientation for re-tensioning. Do
not move the pulleys.
6.
Place an index mark on the edge of each pulley: Mark the Y-axis drive
pulley and the drum pulley where the edges are closest to one another,
disregarding previous marks. Use a distinct color if the pulleys have
been previously marked.
7. Loosen the 3 mounting screws until the bracket slides freely on the
chassis and then re-tighten the screws to 30 in.-lbs.