Xerox Phaser 8860, Service Manual

Page: 253 / 316

09/2007
6-33 Phaser 8860/8860MFP Service Manual
Print Engine Check Menu Tests
Diagnostics Initial Issue
Drive problems on either axis could cause the respective motor to stall and the test to abort.
The Wiper Drive and Drum Maintenance Drive tests would test the basic drive mechanisms. If
the Head Tilt Gear fails to engage the tilt mechanism, the test aborts, and all R values are
undefined. If peak values are high, there could be an issue with a weak Process Drive, friction
in the tilt cam drive train, the cam surfaces (lubrication), the Head Tilt Spring, or something
impeding the Printhead from tilting (warped insulation on the side, X-Axis misalignment, or the
Printhead being compressed against the Electronics Module. If the peak values are low, check
the Head Tilt Spring.
Purge Pump Test
This test exercises the Purge Pump system that includes the pump, hose, and valve. The
purge functions of the Printhead are not tested. If the ink in the Printhead is solid at the time of
the test, the Purge pump is energized for a fixed interval with the bleed valve closed to allow
the pressure to reach a maximum. Next, the purge valve is opened (with the pump still pump-
ing), allowing the pressure to decay. The pressure profile during this sequence indicates the
condition of the system. If the ink is liquid at the time of the test, jetstack temperatures above
120 degrees, the bleed valve remains open for the entire sequence to avoid ink spills.
Drum Maintenance / Transfix Home Test
This test determines if the Process Drive was successfully repositioned to home position by a
previous test or operation. The test drives the Process Drive motor a short distance in both
directions to check if the drive is at home position. When the Process Drive motor is returned to
the start position after each excursion, the motor is driven enough to compensate for the cur-
rent following error (fe), which should put the mechanism back in the initial position. There
should be very little backlash in each drive as there is a restoring force opposing each motion.
The amplitude values may vary more than the time values as amplitude is affected by the
attached mechanisms.
Printhead Clearance Test
This test measures the clearance between the Printhead insulation and the left and right sides
of the chassis when the Printhead is tilted to the Standby position (i.e. back). This measure-
ment could help to determine if the Printhead insulation is loose or warped. The test moves the
X-Axis to the home position, the Printhead is first moved to the Tilt position, then to the
Standby position. Next, the X-axis is moved to the right until the insulation makes contact with
the right side frame and the drive cone unloads from the Printhead. The X axis is then moved
left for a fixed time. Finally, the Printhead is jogged back to the right and then moved to the left
for a fixed time until the insulation starts to make contact with the left side frame. An abnormal
value for either characteristic could indicate a clearance problem.
Table 49 Purge Pump Nominal Values
R# Characteristic Typical Value Result
0 Jetstack Temperature (deg) N/A Reports the maximum of the current jet-
stack temperatures.
1 Pump PWM (percent) N/A Reports the current PWM value being
used to drive the pump.
2 Start Power (watts) N/A Reports the initial peak pumping power
following power on to the pump.
3 Initial Pumping Power (watts) N/A Reports the minimum pumping power
value following the start up peak (R2). If
the pump is pumping the normal volume,
then the drop is significant and the pres-
sure rises slower. If the volume is small,
hose pinched or plugged near the pump,
then the drop is minimal and the pres-
sure rises quickly.
4 Max Pressure Pumping
Power N/A Reports the max pumping power during
the pumping interval.
5 Max Pressure Average
Pumping Power N/A Reports the average pumping power in
the area of highest pressure. If this value
is much different than R4, it might indi-
cate pressure fluctuations when pumping
at max pressure.
6 Pumping Time To Average
Power (sec) N/A Reports the time from pump on until the
average pressure is reached.
7 No Pressure Pumping Power
(watts) N/A Reports the average pumping power
after the pressure has fully decayed
(purge valve open).
8 Pressure Decay Time (sec) N/A Reports the time between the purge
valve opening and the point when the
pumping power (relative to the current
pressure), fades back into the ripple of
the no pressure pumping power. See R7.
Table 50 Drum Maintenance / Transfix Home Nominal Values
R# Characteristic Typical Value Result
0 DM Initial fe Peak (pm motor
counts) N/A Reports the height of the initial peak
when starting rotation of the drum main-
tenance drive gear.
1 DM Initial fe Peak Time (sec) N/A Reports the time since the start of CCW
motion until the peak was detected.
2 TF Initial FE Peak (pm motor
counts) N/A Reports the height of the initial peak
when starting rotation of the transfix
drive gear.
3 Transfix Initial fe Peak Time
(sec) N/A Reports the time since the start of CW
motion until the peak was detected.
Table 51 Printhead Clearance Nominal Values
R# Characteristic Typical Value Result
0 Tilt To Left Contact Distance
(min) N/A Reports the approximate clearance
between the left side of the Printhead
and the chassis.
Table 49 Purge Pump Nominal Values
R# Characteristic Typical Value Result