Ricoh A085, Manual

Page: 580 / 617

2.2 DIRTY BACKGROUND
- Phenomenon -
1. Dirty background at image density level 4 (manual setting).
2. ADS copies have a dirty background.
- Possible Causes -
1. V
L
correction failure
• Very dirty optics (V
L
correction cannot compensate).
• Deteriorated exposure lamp (maximum output cannot give sufficient
light intensity).
•
Failure of the dc power supply board.
•
Dirty erase lamp unit.
2. V
R
correction failure
• High voltage supply board - CTBG (development bias) failure.
• Poor contact of development bias.
•
The development bias is grounded.
3. OPC drum is not grounded properly.
4. ADS mode
•
Improper ADS Density setting (SP34).
•
ADS Sensor board failure.
•
High voltage supply board - CTBG failure.
•
Incorrect adjustment of ADS sensor (SP56/SP167).
5. High toner density
• Improper setting of grid bias correction data (SP62).
•
Improper grid bias setting (SP161).
•
Improper ID sensor pattern bias (SP33/75).
•
Dirty erase lamp unit.
Trouble- shooting
12 February 1992 COPY QUALITY
6-5