Hot Fuser Service Check - Lexmark 7003-050 X340n Service Manual

7003-XXX
Fuser service check (continued)
FRU
Lamp cable
LVPS/HVPS
Fuser

Hot fuser service check

Note: Ensure correct fuser is installed.
FRU
Fuser AC cables
LVPS/HVPS
Fuser
2-24
Service Manual
Action
Unplug the MFP and disconnect the fuser lamp cable plug from the
LVPS/HVPS board connector CN102.
Check for continuity across the fuser lamp by checking across the
connector pins.
• If there is continuity, go to Step 1: Continuity.
• If there is no continuity, go to Step 2: No continuity.
Step 1: Continuity
Turn the MFP on with only the fuser power disconnected.
Measure the voltage at connector CN102 on the LVPS/HVPS. It
should match the line voltage.
If line voltage is not present, see
page 2-25 for more information.
Make sure the fuser thermistor is correctly connected to the controller
board. If the problem persists, disconnect the thermistor cable at J15
and check for less than +5 V dc on pin 1. Pin 2 should be ground.
If line voltage is incorrect on pin 1, see
check" on page 2-21 for more information.
Step 2: No continuity
Check the lamp cable for continuity.
• If correct, replace the fuser.
• If incorrect, replace the lamp cable.
Disconnect the thermistor cable from J15 on the controller card.
Measure the resistance across the ends of the thermistor cable. See
"Controller card" on page 5-4
Replace the fuser assembly if the resistance is lower than 1K ohm or
shorted.
Note: Resistance measures approximately 240K ohms when cool
and 1.4K ohms hot.
Action
Measure the resistance of the thermistor. The resistance measures
from approximately 1K ohms immediately after printing or POR to
approximately 240K ohms when thermistor reaches room
temperature. (It may take 30 minutes to cool.)
Replace the fuser assembly as necessary.
"LVPS/HVPS service check" on
"Controller card service
for more information.