Service Manual
6-15
Troubleshooting
6
6.
Be sure that the thermal head leaf spring (which presses against the
right end of the thermal head when it's in its print position) is in good
contact with the thermal head. If it isn't, bend the leaf spring until it
makes good contact and keeps the thermal head from making any
side-to-side motion during printing.
7.
Check for a defective drum motor drive. Ensure it doesn't jerk,
chatter, or lug down.
8.
Test the torque limiter, located next to the right end of the transfer
roll's supply spool. It should rotate in one direction only, and it should
offer a small amount of resistance to being turned. The torque limiter
supplies a constant amount of back-tension to the motion of the
transfer roll to keep it taut.
9.
Check for nicks or burrs in the paper path (particularly the front
cover) that could impede the loading of a sheet of media into the
paper clamp.
10.
Perform the Chapter 9 procedure “Adjusting for best print quality” on
page 9-16.
11.
Replace the thermal head. This is explained in the Chapter 8 topic
“Thermal head” on page 8-18.
Not printing
The printer processes a sheet of paper, but no image is printed on it.
1.
Ensure that the thermal head temperature-adjust DIP switches are
correctly set for the resistance of the thermal head. Refer to the
Chapter 9 topic “Adjusting for best print quality” on page 9-16."
2.
Ensure that the thermal head power and data cables are properly
connected.
3.
Measure the power being supplied to the thermal head (refer to the
earlier topic “Verifying power supply operation” on page 6-3). If no
DC voltage is being supplied to the thermal head, then troubleshoot
the power supply and the wiring harness leading to the thermal head.
4.
Inspect the data wiring harness leading from the engine control board
to the thermal head for nicks, cuts, or damage.
5.
If everything checks out in the previous steps you can assume that the
data drivers on the print engine control board are bad; replace the
print engine control board. Refer to the Chapter 8 topic, “Engine
control board” on page 8-40.