Troubleshooting
Phaser 6121MFP Multifunction Printer
User Guide
187
2-Sided Printing Problems
If you have problems when copying or printing on two sides of a sheet, then the media you are using or 
the settings you are using are probably not correct.
• Make sure that you are using approved media. Only plain paper in either Letter or A4 size can be 
used in the duplex unit.
• Do not do 2-sided printing on envelopes, labels, postcards, thin or think card stock, letterhead, or on 
plain paper with a size other than Letter or A4.
• Make sure you have not mixed media types in the tray.
• In the printer driver Layout tab, under Print on Both Sides, choose Short Edge Binding (flipped as 
on a clipboard) or Long Edge Binding (flipped as in a loose-leaf notebook).
• For 2-up on 2-sided pages, choose Collate only in the printer driver’s Basic tab. Do not set collation 
in the application.
• Make sure the duplex speed setting is appropriate to your situation. See Changing the Duplexing 
Speed on page 187.
Changing the Duplexing Speed
If you are having problems with image transfer during 2-sided printing or copying, you can change the 
duplexing speed.
To change the duplexing speed:
1. On the printer control panel, press the Back/Menu button to enter the System Menu, then press 
the Down Arrow button to go to General Setup. Press the OK button.
Some areas of the scanned 
image are missing.
Acrobat 8 (Macintosh version) is 
used for scanning the image.
With the Acrobat Scan setting, turn 
off the OCR and Filtering functions.
The paper is wrinkled. The paper is moist from humidity or 
spilled water.
Remove the moist paper and 
replace it with new, dry paper.
The media feed roller or fuser unit is 
defective.
Inspect them for damage. If 
necessary, contact Technical 
Support.
You are using unsupported media 
(wrong size, thickness, type, etc.).
Use Xerox-approved media only. 
See Supported Paper and Media on 
page 52.
Data was sent to the printer but 
it does not print.
An error message is displayed in the 
control panel menu.
Handle according to the message 
displayed.
It takes a very long time to 
transfer scan data to the USB 
flash drive.
The response time may be slow 
depending on the USB memory 
device that is used.
Wait until the transfer is finished.
You cannot enter Scan mode or 
Fax mode.
An error has occurred in Copy mode. Correct the cause of the error and 
then select a different mode.
Symptom Cause Solution