Xerox WorkCentre Pro 423 Service Manual page 254

WorkCentre Pro 423/428
2) Light copies
l Check
1. Check that the values are correctly set up in the Diag Code [21-5] to [21-37]. (See
NVM table)
2. Check that the ROS window is not contaminated.
3. Print out the built-in Test Pattern of continuous gradation in the Diag Code [23-21].
Check that the darkest two black bands in the Test Pattern copy has almost the
same density as 1.3 solid.
•
When the density is lower, the problem can be Xero related.
•
When the density is almost the same, the IIT may have the problem.
l When the density of built-in Test Pattern is normal
A. Check the IIT.
•
When the auto
Check that the setup data in the Diag Codes below are appropriate. (See NVM
table) Change the data as needed. [21-25,26,31to37]
•
When the manually
Check that the setup data in the Diag Codes below are appropriate. (See NVM
table) Change the data as needed. [21-5 to 24]
B. Check the control board.
Problem of control board rarely causes light copies, but when the problem persists
after conducting the above checks, use a built-in Test Pattern and check each
board for problems.
3) When the image is too light at one half side of copy
Print out the built-in Test Pattern with continuous gradation in the Diag Code [23-23].
Check for a light image at one half side of the copy.
l When the outboard side (front side of the machine) is light,
The CRU has not been properly installed.
l When the built-in Test Patterns does not show light images, check the IIT white
reference board for contamination. (Particularly for the DADF white reference
board)
4) High background for the entire image or density is too dark
Print out the built-in Test Pattern of the entire white copy in the Diag Code [23-10] and
of continuous gradation in the Diag Code [23-23]. Check for high-background in the
entire image.
When the entire image has background, poor toner charging can be the cause.
(Replace the CRU.)
controlled density is too
controlled density is too
3-10 CHAPTER 3 IMAGE QUALITY TROUBLESHOOTING
When the built-in Test Pattern has background, check XERO related components
(CRU, BTR, or DST) for problems.
•
Replace the CRU, then HVPS.
l When the built-in Test Pattern has no background
A. Check the IIT.
•
When background
Check the data setup in the Diag Codes [21-25] to [21-57] are appropriate.
(See NVM table) Change the data as needed.
•
When background is observed in the manually adjusted density
•
Check the white reference board for pieces of paper, dust or foreign
matter.
•
Check that the data setup in the Diag Codes [21-5 to 24] are appropriate.
light (See NVM table) Change the data as needed.
B. Check the control board.
light If the problem persists, use the built-in Test Pattern to check each board for
problems.
3.3 Image Quality Troubleshooting
is observed in the auto adjusted density