Ricoh Gestetner 5450, Service Manual, Page: 69 / 315

1 July, 1998 DRUM
2-41
Detailed
Descriptions
Ink Detection Board
Ink Detection Mechanism
The ink detecting pins [A] function as a capacitor electrode and detect the
capacitance between the ink [B] and doctor [C] rollers. The capacitance level
changes with the ink level. When the ink level is high the pins touch ink, and the
capacitance increases. When the ink level is low the pins do not touch the ink and
the capacitance therefore decreases. Consequently, by detecting the capacitance
between the pins, the ink supply motor maintains the ink level.
If the pins detect an insufficient amount of ink after activating the ink pump motor
for 40 seconds, a "no ink condition" is detected. Guidance is displayed on the
operation panel.
NOTE: The ink supply mode is useful when installing a new drum. When the
“Economy Mode” key is pressed while holding down the “0” key, the drum
turns 40 rotations, to supply ink inside the drum.
The ink detection board [D], which includes the ink detection circuit, is also inside
the drum. There are test pins (TP's) and a potentiometer (VR901) for ink detection
adjustment.
C229D011.WMF
C229D110.WMF
[C]
[B]
[A]
[D]