Ricoh FT4480 Field Service Manual page 219

15 March 1987
D I R T Y B A C K G R O U N D
1. DIRTY BACKGROUND ON
ENTIRE COPY IMAGE
- Possible Causes -
Dirty corona wire
Toner supply clutch malfunction
Incorrect lamp regulator output
Dirty drum and bias thermistors
Inefficient drum cleaning
Incorrect corona current
Drum worn out
- Action -
Note: When the problem occurs after the drum conditioning, make several
white copies or cycle the development unit for 2 minutes using free run.
Make a reduced copy with A3/11" x 17" paper. Does the dirty
appear in the erased areas?
Y
Clean the drum thermistor and bias thermistor surfaces.
Clean the charge corona wire.
Clean the optics.
If the problem was not resolved, adjust the lamp regulator
If the problem still exists, check and adjust the charge corona
current.
o Clean the erase unit.
o Clean the drum heater thermistor and bias thermistor surfaces.
Do wavy lines occur with the dirty background?
N
Y
I
Does the toner supply clutch turn off?
Y N
I
Is the toner supply solenoid (CN230-3, -4) continuously supplied
with +24 volts
Y N
I
Check/replace the dc power supply and/or the main board.
9-14
background
output.