Service manual

DEVELOPING UNIT
2-G-4
2 UNIT EXPLANATION
[6] Dmax Control
Dmax control is performed by the TCSB (toner
control sensor board), M2 (drum), M3 (develop-
ing), and so on. These parts are controlled by the
PRCB (printer control board). Related boards
and sensors are DPSB (drum potential sensor
board), DPS (drum potential sensor), and TH5
(drum temperature sensor).
When the front right or left door of this machine
opens or closes, MS1 (interlock 1) or MS2 (inter-
lock 2) operates to interrupt the DC power supply
to the motor, stopping the M2 and M3.
1. Operation
The purpose of Dmax control is to adjust the
maximum density to the reference level for each
machine.
a. Dmax control
(1) Method
Latent images are created several times at the
maximum exposure level, images are developed
with the rotational speed of the developing
sleeve varied, then each density is read by the
Dmax sensor (PD1) on the TCSB.
The developing sleeve speed detected when the
density has reached the reference level is
recorded as the optimum sleeve speed and the
developing is performed at this optimum sleeve
rotation speed.
(2) Timing
a) When the fixing temperature is lower than
50°C at power ON.
b) At the end of job after every 20,000 copies.
PRCB
DCPS2
DCPS1
DPSB
DPS
TCSB
24VDC
24VDC
PGND
12VDC
5VDC
SGND
M2 CONT
M2 F/R
SGND
M2 EM
M3 CONT
M3 CLK
M3 EM
DPS ANG
AGND
TH5 ANG1
TH5 ANG2
5VDC
Dmax LED CONT
/Dmax LED Vref
JAM LED CONT
Dmax SIG
Dmax MONI
JAM SIG
MS2 MS1
M2
M3
DPS DRIVE A
DPS DRIVE B
DPS ANG 1
DPS ANG 2
TH5
Di850g.book4ページ２００２年７月１２日 金曜日 午前８時３６分