M3 (Developing Unit Drive) Control; Developing Bias Control - Minolta Di850 Service Manual

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DEVELOPING UNIT

[3] M3 (Developing Unit Drive) Control

24VDC
PGND
DCPS2
M3 CONT
M3 CLK
M3 EM
PRCB
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
MS2
MS1
M3
2-G-2

[4] Developing Bias Control

24VDC
5VDC
SGND
B CONT
B SHIFT
B FB
PRCB
5VDC
SGND
DCPS1
24VDC
MS2 MS1
24VDC
PGND
DCPS2
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.
B SHIFT duty
Developing bias output range -300 V to -800 V
BIAS
HV1
20% to 80%

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