Lexmark X 850 Owners Manual

Diagnostic information2-203
7500-XXX
Tray 4 media size failure
StepCheckYe sNo
1Check the media. 
Pull out tray 4, and visually check it.
Is the media loaded in tray 4 properly?Go to step 2.Load media 
properly.
2Check the media.
Pull out tray 4, and visually check it.
Are the front media guide and rear media guide on tray 
4 set correctly?Go to step 3.Set the parts 
properly.
3Check the switch (TTM media size) for proper 
installation.
Pull out tray 4, and visually check it. 
Is the switch (TTM media...

2-204MFP Service Manual 7500-XXX
Tr a y 3 media size mismatch in length
StepCheckYe sNo
1Check the media. 
Pull out tray 3, and visually check it.
Is the media loaded in tray 3 properly?Go to step 2.Load media 
properly.
2Check the media. 
Pull out tray 3, and visually check it.
Are the front media guide and rear media guide on 
tray 3 set correctly?Go to step 3.Set the parts 
properly.
3Check the switch (TTM media size) for proper operation.
Pull out tray 3, and visually check it.
Is the switch (TTM...

Diagnostic information2-205
7500-XXX
9Check the roll. 
Open the printer left door assembly, and visually check 
it.
Is the registration roll assembly for transport free of 
excess wear and contamination?Go to step 10.Clean or replace the 
registration roll 
assembly.
Go to “Registration 
roll assembly 
removal” on 
page 4-79.
10Check the sensor (registration) for proper operation.
1. Enter the Diagnostics Menu.
2. Touch BASE SENSOR TEST.
3. Touch Media Path.
4. Touch Registration.
Open the printer left...

2-206MFP Service Manual 7500-XXX
Tray 4 media size mismatch in length
StepCheckYe sNo
1Check the media. 
Pull out tray 4, and visually check it.
Is the media loaded in tray 4 properly?Go to step 2.Load media 
properly.
2Check the media. 
Pull out tray 4, and visually check it.
Are the front media guide and rear media guide on 
tray 4 set correctly?Go to step 3.Set the parts 
properly.
3Check the switch (TTM media size) for proper 
installation.
Pull out tray 4, and visually check it.
Is the switch (TTM...

Diagnostic information2-207
7500-XXX
8Check the roll. 
Open the printer left door assembly, and visually check 
it.
Is the media transport roll assembly for transport free of 
excess wear and contamination?Go to step 9.Clean or replace the 
media transport roll 
assembly.
Go to “2000-sheet 
dual input (TTM)–
2TM/TTM media 
transport roll 
assembly removal” 
on page 4-246.
9Check the roll. 
Open the printer left door assembly, and visually check 
it.
Is the registration roll assembly for transport free of...

2-208MFP Service Manual 7500-XXX
Image quality trouble
Troubleshooting
Note:  First, get a printout as a base, and follow the symptom table to identify the possible failing FRU’s. 
Image quality symptoms: 
•
Faint print (low contrast)– “Faint print (Low contrast)” on page 2-209.
•Blank print (no print)– “Blank print (no print)” on page 2-211.
•Solid black– “Solid black” on page 2-213.
•Vertical blank lines (White stripes in media transport direction)– “Vertical blank lines (white stripes in 
media...

Diagnostic information2-209
7500-XXX
Image Quality 
Faint print (Low contrast)
Before starting, check the media route for foreign objects, such as staples, clips, and scraps, in the media path. 
Step Check Yes No
1 Check the media condition.
Load new, dry, recommended media, and perform a print 
test.
Is the image density normal?Problem solved. Go to step 2.
2 Check the toner cartridge.
Install a new toner cartridge.
Re-print the defective image.
Is the image density normal?Problem solved. Go to step 3....

2-210MFP Service Manual 7500-XXX
6 Check the image development process.
Perform a print test. Turn off the printer power while 
printing.
Carefully remove the PC cartridge, and check the 
developed image formed on the drum right before the 
transfer roll assembly. 
Is the image completely formed on the drum, and the 
area clear, black, and easy to read?Go to step 7. Go to step 9.
7 Check the image transfer process.
Check the toner image formed on the drum after the 
transfer roll assembly.
Is the toner...

Diagnostic information2-211
7500-XXX
Blank print (no print)
Check the media path for foreign objects such as staples, clips, scraps of media.
Step Check Yes No
1 Check the toner cartridge.
Install a new toner cartridge.
Re-print the defective image.
Is the image density normal?Problem solved. Go to step 2.
2 Check the transfer roll assembly.
Remove the transfer roll assembly.
Check the transfer roll assembly rotation. 
Is the transfer roll assembly free of excess wear and 
contamination?Go to step 3....

2-212MFP Service Manual 7500-XXX
6 Check the printhead installation.
Is the printhead assembly installed properly with four 
screws?Go to step 8. Go to step 7.
7 Check the printhead assembly installation. 
Install the printhead assembly properly, and perform a 
print test.
Does the error continue?Problem solved. Go to step 8.
8 Check the printhead for proper connection.
Warning: If too much force is applied to the board when 
checking it, the printhead could become misaligned. Go to step 9. Replace the...