Oki ES3640MFP Service & Troubleshooting Manual page 58

Random Bands, Lines, Marks, or Missing Spots
There are areas of the image extremely light or are missing entirely and do not appear to
be a repeating defect or in a single color.
Caution
Leaving an Imaging Unit exposed to light for periods in excess of 10 minutes can quickly
degrade its performance and result in early failure.
Initial Actions
Perform Initial Actions from
Using a flashlight, carefully examine the area around the Imaging Units and the
openings between the Imaging Units and LED Heads. Small obstructions, such as hair or
fibers, can create streaks
When troubleshooting, print a
problem. The problem may be a
Random missing spots can also be associated with
the page in certain areas. Usually this will occur in high-coverage areas where the fuser
temperature is not high enough to fuse the toner on the media. This causes toner to be
re-deposited further down the page
Areas of the Printer that Apply to Random Bands, Lines, Marks, or Missing Spots
1. Check for obstructions between the LED Heads and the Imaging Units. Remove
the Imaging Unit and inspect each Drum and corresponding area. Remove any
debris.
2. Replace the Imaging Unit. Does the image quality improve?
3. Replace the Transfer Unit. Does the imaging quality improve?
4. Replace the Fuser. Does the image quality improve?
5. Replace the LED Head. Does the image quality improve?
Print Quality Troubleshooting Practices
test print
repeating defect
.
Imaging Unit
Fuser
Transfer Unit
Engine Control Board
Troubleshooting Steps
on at least letter size paper for diagnosing this
that is not noticeable on smaller media.
"Cold Offset", which lifts toner off
Resolution
Yes – Remove the obstruction or
debris.
No - Go to Step 2.
Yes – Complete.
No - Go to Step 3.
Yes – Complete.
No - Go to Step 4.
Yes – Complete.
No - Go to Step 5.
Yes – Complete.
No – Replace the engine PCB.