Ricoh FAX2900L Service Manual page 51

PRINTING
Cleaning Mode
If the paper is smaller than the printed image, or if a paper jam occurs during
printing, toner may transfer to the roller surface. To prevent this from occurring, the
transfer roller is cleaned before the next printing run.
While the machine is cleaning the transfer roller, the power pack supplies -1200V
to the transfer roller, and charges the drum to -750V. The negatively charged toner
on the transfer roller transfers back to the drum.
The machine cleans the transfer roller under the following conditions:
• At power on (when the fusing temperature reaches half of the standby
temperature).
• When the cover is opened and then closed during the printing process.
• After clearing a printer jam.
The CPU controls the transfer roller voltage through the power pack using the
following signals.
In
Out Transfer Roller
THTRG
TLPWM
+ 5.0 µA
On Off
Off On
- 1200 V
2-24
21 May, 1999
On Off
On Off
- Off