Ricoh FT5233 Service Manual page 50

12 February 1992
3.3 GRID BIAS VOLTAGE CORRECTION
The grid bias voltage differs depending on the modes and correction factors
(see the process control section).
3.3.1 Base Grid Bias Voltage
There are two base grid bias voltages, one for image and the other for sensor
patterns (ID sensor pattern and V
Grid bias voltage for image (Vgi):
Grid bias voltage for sensor pattern (Vgp): -500 V
The high voltage supply board - CTBG is adjusted at the factory to output the
correct Vgi and Vgp. When the high voltage supply board - CTBG is replaced
in the field, the variation of the grid bias output should be corrected by
entering the grid voltage correction data in SP mode #62.
3.3.2 Manual ID Correction
When the image density is selected by
the manual image density keys on the
operation panel, the grid bias voltage is
changed as shown in the above table.
The image density for each manual ID
level is also controlled by the exposure
lamp voltage and the development bias
voltage. The manual ID correction for
the grid bias voltage is applied only to
levels 6 and 7. This is to expand the
difference of image density at levels 6
and 7 from the other manual ID levels.
pattern).
R
-745 V
ID Level Grid Bias Voltage
1
2
3
4
5
6
7
NOTE: Vgi
2-21
DRUM CHARGE
Vgi ±0V
Vgi ±0V
Vgi ±0V
Vgi ±0V
Vgi ±0V
Vgi +50V
Vgi +50V
(Grid bias voltage
for image)= –745V