Tektronix 1235N - Phaser Color Laser Printer, Service Manual

Page: 67 / 240

Service Guide 53
Poor fusing, toner offsetting
1. Is a supported paper type being
used? Try printing on a
different brand of paper.
2. Is the fuser unit properly
installed and making good
electrical contact with the print
engine? Inspect its connector.
3.
Inspect the fuser. Are its rollers
contaminated or damaged?
4. Ensure the media type is
correctly set.
5. Does AC voltage appear
between Pins 1 and 2 of CN 4-1
and CN 4-2 of the fuser
connector. These pins connect
to Pins A and B on the fuser’s
underside when the fuser is
installed; remove the fuser to
check. If not, replace the power
supply.
6. Is the resistance of the fuser’s
upper roller thermistor (at room temperature) between 190 to 980 ohms? If
not replace the fuser.
7. Is the resistance of the fuser’s lower roller thermistor (at room temperature)
between 190 to 980 ohms? If not replace the fuser.
8. Is the fuser temperature correct during printing? Run the maintenance
mode fuser test “Test printing” on page 71 and check the temperature
displayed on the controller panel.
9. Replace the engine controller board. Transfer the old engine controller
board’s EEPROM (lower-right corner of board) to the new engine controller
board.
Offsetting and fuser temperature. Offsetting occurs on specialty paper if the
fuser’s temperature does not match the paper loaded in the multi-sheet bypass
feeder. For cold-offsetting, characterized by toner flaking off the completed print,
you want to raise the fuser’s temperature. For hot-offsetting, characterized by
toner pulled off print as it is fused, you want to lower the fuser’s temperature.
The chart below lists the specialty paper types and relative fuser temperatures
used. To correct offsetting, select the next paper type above or below the current
paper type you are using. Removing and reloading paper in the multi-sheet
bypass feeder, prompts you for the paper type at the control panel.
Hottest fuser temperature used
Cardstock
Label/Envelope
Glossy
Letterhead/Light Cardstock
Plain Paper/Transparency film
Coolest fuser temperature used