3-20 Phaser 7750 Printer Service Manual
2
1. Enter service diagnostics and run the 
Clear Tech Rep Fault (see pg. 6-20) 
04-346 procedure.
2. Enter the Adjustments/Calibrations 
menu and run the Belt Edge Learn 
Test with the right hand door open and 
the door interlock held actuated.
3. Does the accumulator belt rotate 
during the test?
Go to step 3.  Go to step 6.
3
1. Remove the accumulator belt 
assembly.
Caution: Removing the accumulator 
belt assembly allows light into the 
imaging unit area, avoid exposing the 
imaging units to light.
2. Is the belt home marker present?
This is a 7 mm, square, silver patch 
on the rear edge, inside the belt. 
Rotate the belt if you cannot see the 
marker.
Go to step 4. Replace the 
accumulator belt 
assembly.
4
1. On the accumulater belt assembly, 
rotate the belt drive gear in the normal 
process direction until the belt home 
marker is positioned beneath the belt 
home sensor.
2. Reinstall the belt assembly.
3. Enter service diagnostics and run the 
Accum MOB Sensor test.
4. Is “MOB sensor is H” displayed?
Replace in the 
following order:
■ engine control 
interface board
■ engine control 
board
Go to step 5.
5
1. Replace the accumulator belt 
assembly.
2. Retest.
3. Does error 30 return?
Troubleshoot and 
repair using the 
Reflective Sensor 
Procedure on 
pg. 3-45.
Complete.
6
1. Partially remove the accumulator belt 
assembly.
2. Manually rotate the drive gear 
clockwise.
3. Does the belt turn freely?
Go to step 14. Go to step 7.
7
1. Inspect the a.ccumulator belt cleaner 
and waste auger for packed toner.
2. Are the belt cleaner and auger clean 
and free of toner?
3. Do the gears rotate freely?
Go to step 9. Go to step 8.
Troubleshooting Procedure  (Continued)
Step Actions and Questions Yes No