Service Manual
9-31
Checks and Adjustments
9
Adjusting for an aged printhead
As a printhead ages, its print quality may change. It may not eject ink droplets
with the same force as when it was new; the flight-time of the ink droplets has
decreased. This results in bidirectional mis-convergence. This can be adjusted
for. If you encounter a printer that has lost convergence or has its Standard and
Enhanced convergence values significantly changed, then you should follow
these steps to adjust the printhead’s convergence:
1.
Set the printhead-to-media spacing (tailpiece adjustment) as explained
earlier in the topic, “Printhead-to-media adjustment (tailpiece
adjustment)” on page 9-15.
2.
Ensure that the printhead tilt is correct. Correct it if it is not, as
explained in the topic, “Tilt adjustment” on page 9-24.
3.
Scroll to the Extended Service Support mode and scroll to the menu
item Standard
Convergence
menu item. It will display a value such
as:
Convergence: 44
. Use the arrow keys to set the displayed
value to 40; the printhead default value. Press
Select
to exit the
menu, which saves the displayed value 40. Scroll to the
Enhanced
Convergence
menu item and set it to 40. Scroll to the
Standard
Head Temp
menu item and the
Enhanced Head Temp
menu items
and set each to 0.
4.
Scroll to and enter the
Extended Service Support
menu and then
scroll to the
Convergence Pattern
menu item. Press
to
print a test pattern to determine if a change is required.
5.
Examine the Standard mode alignment marks in the test print. If the
center of the alignment mark is shifted to the left (minus direction —
this is called a “slow” printhead), then the printhead voltage needs to
be raised. (Refer to the earlier topic “Bi-directional print convergence”
on page 9-21 for details on interpreting a convergence test print.)
6.
Measure the HV+ and HV- voltages at the engine control board’s
power connector at the power supply; Pin 1 is HV+, Pin 2 is ground,
and Pin 3 is HV-. Increase HV+ and HV- in 1 VDC increments. Keep
the + and - values the same; that is, if the “+” value is +79, the “-”
value should be -79. Increasing HV+ and HV- decreases the ink
droplets flight-time to its original, expected value.
7.
Press
to print a convergence test pattern so you can determine
if a convergence change is required. Examine the test print alignment
marks for standard mode printing mis-convergence.
8.
If mis-convergence still shows, repeat Step 5, increasing HV+ and HV-
in 1 VDC increments, and repeat Step 6, printing a test print and
checking the alignment marks, until alignment is correct.
9.
If the Enhanced printing mode alignment patterns show
mis-convergence, you can scroll to the
Enhanced Convergence
menu item and “fine-tune” the convergence as explained in the
topic,“Bi-directional print convergence” on page 9-21.
