Transfer/Separation Control - Minolta Di850 Service Manual

[4] Transfer/Separation Control

24VDC
PGND
DCPS2
24VDC
T CONT
S CONT
SEL
T SIG
S SIG
SGND
PGND
ADUSDB
S SHIFT(DC)
S FB(AC)
S FB(DC)
S SHIFT(AC)
T SHIFT
PRCB
The transfer and separation corona unit is controlled by
the PRCB (printer control board) and ADUSDB (ADU
stand drive board) via the HV2 (high voltage unit 2).
Between the PRCB and ADUSDB, signals are
exchanged using serial data. When the front door of
this machine opens or closes, MS1 (interlock 1) or MS2
(interlock 2) operates to interrupt the DC power supply
to HV2, stopping the voltage supply to the transfer and
separation corona unit.
1. Operation
a. Transfer
Positive DC high voltage is used for toner transfer
to the drum surface.
b. Separation
AC high voltage is used for toner separation from
the drum surface.
2. Signals
a. PRCB input signals
(1) S FB (AC) (HV2 to PRCB)
Toner separation (AC) current feedback signal.
This signal monitors the toner separation (AC)
current. It is a 0 to 5V analog signal correspond-
ing to the output level.
(2) S FB (DC) (HV2 to PRCB)
Transfer and separation (DC) current feedback
signal.
This signal monitors the toner transfer and sep-
aration (DC) current. It is a 0 to 5V analog signal
corresponding to the output level.
SEPARATION
TRANSFER
HV2
2-F-3
CORONA UNIT SECTION
b. PRCB output signals
(1) T SHIFT (PRCB to HV2)
Transfer corona unit output level control signal.
This signal controls the level of the output to the
transfer corona unit according to the duty ratio of
the pulse (PWM) signal sent from the PRCB.
T SHIFT duty
Transfer DC output range 70µA to -700µA
(2) S SHIFT (DC) (PRCB to HV2)
Separation corona unit output level control sig-
nal.
This signal controls the level of the output (DC
bias component) to the separation corona unit
according to the duty ratio of the pulse (PWM)
signal sent from the PRCB.
S SHIFT duty
Separation DC output range 0µA to -300µA
(3) S SHIFT (AC) (PRCB to HV2)
Separation corona unit output level control sig-
nal.
This signal controls the level of the output (AC
component) to the separation corona unit
according to the duty ratio of the pulse (PWM)
signal sent from the PRCB.
S SHIFT duty
Separation AC output range 500µA to 1400µA
c. ADUSDB input signals
(1) T SIG (HV2 to ADUSDB)
Leak or short toner transfer abnormality detec-
tion signal.
[L]: Normal
[H]: Abnormal
(2) S SIG (HV2 to ADUSDB)
Leak or short toner separation abnormality
detection signal.
[L]: Normal
[H]: Abnormal
20% to 80%
20% to 80%
20% to 80%