Service manual
DEVELOPING UNIT
2-G-2
2 UNIT EXPLANATION
[3] M3 (Developing Unit Drive) Control
M3 (developing) is controlled by the PRCB (printer
control board) and the motor drive power is supplied by
DCPS2 (DC power supply unit 2). When the front left
or right door of this machine opens or closes, MS1
(interlock 1) or MS2 (interlock 2) operates to interrupt
the DC power supply to M3, stopping the voltage sup-
ply to the developing sleeve.
1. Operation
M3 which is the 24V driven DC motor drives the
developing sleeve and agitator. M3 equipped
with speed control circuit send the rotation error
signal to PRCB when PLL lock is released longer
than the specified time period. M3 starts after the
specified time interval from the start switch is
ON, and stops after the specified time interval
from the charging wire unit stops charging.
2. Signals
a. Input signals
(1) M3 EM (M3 to PRCB)
M3 fault detection signal.
[H]:Abnormal rotation (when PLL is unlocked for
more than 1.5 seconds)
[L]: Normal rotation
b. Output signals
(1) M3 CONT (PRCB to M3)
M3 drive control signal.
[L]: M3 ON
[H]:M3 OFF
[4] Developing Bias Control
The developing bias is controlled by PRCB (printer
control board) via the HV1 (high voltage unit 1). When
the front left or right door of this machine opens or
closes, MS1 (interlock 1) or MS2 (interlock 2) operates
to interrupt the DC power supply to HV1, stopping the
voltage supply to the developing sleeve.
1. Operation
The developing bias voltage is applied to the
developing sleeve based on the M2 (drum) rota-
tion state signal.
2. Signals
a. Input signals
(1) B FB (HV1 to PRCB)
Developing bias voltage feedback signal.
This signal monitors the developing bias voltage.
It is an 0V to 5V analog signal corresponding to
the output level.
b. Output signals
(1) B CONT (PRCB to HV1)
Developing bias output ON/OFF control signal.
[L]: Developing bias ON
[H]:Developing bias OFF
(2) B SHIFT (PRCB to HV1)
Developing bias output level control signal.
The developing bias output level is controlled
according to the duty ratio of the pulse (PWM)
signal sent from the PRCB.
PRCB
DCPS2
M3
24VDC
PGND
M3 CONT
M3 CLK
M3 EM
MS2 MS1
B SHIFT duty 20% to 80%
Developing bias output range -300 V to -800 V
PRCB
24VDC
5VDC
SGND
B CONT
B SHIFT
B FB
5VDC
SGND
24VDC
24VDC
PGND
DCPS1
DCPS2
HV1
MS2 MS1
BIAS
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