HP 8550 Service Manual - Page 483

The face or back of the copy paper is soiled Unit Printer Cause Cassette pickup roller, registration roller, lower fusing roller, feeding roller Step 1 Secondary 2 transfer belt assembly, fusing inlet guide, fusing/ separation lower guide, separation guide ITD cleaning 3 4 5 Fusing 6 assembly High-voltage 7 PCB 2 (ITD cleaning bias or fusing/ separation bias output absent) ITD cleaning 8 roller drive assembly 9 Checks Yes/No Action Does the soiling have a specific interval that matches the diameter of the cassette pick-up roller, registration roller, lower fusing roller, feeding roller? YES See "Repetitive image defects" on page 482. Identify the soiled roller, and clean it. If the dirt cannot be removed, replace it. Is the secondary transfer belt assembly, fusing assembly inlet guide, fusing/separation lower guide or separation guide soiled? YES Clean the soiled part. If the dirt cannot be removed, replace the part. Are there scratches or dirt YES in the peripheral direction of the ITD cleaning roller? Are the contacts soiled on YES either of the following? l ITD cleaning roller (for ITD cleaning bias) l ITD cleaning mechanism Does the problem occur in YES a high-humidity environment? Are the contacts soiled on YES either of the following? l fusing assembly l fusing/separation bias Replace the high-voltage PCB 2. Is the problem corrected? YES Replace the ITD cleaning roller. Clean the contact. If it is damaged, replace the problem part. Also, check for a displaced part. Wipe the surface of the intermediate transfer drum with a moistened flannel cloth; then, dry wipe it with lint-free paper. Clean the contact. If it is damaged, replace the problem part. Also, check for a displaced contact. End Is the drive gear (used to YES transmit locking/unlocking) of the ITD cleaning roller worn or cracked? Is the cam used to lock/ unlock the ITD cleaning roller worn or cracked? YES Replace the worn or cracked part. Replace the worn or cracked part. EN Copy module troubleshooting 481