Xerox WorkCentre Pro 412 Service Manual page 57

5-5-7-4 MHV (Electrification Output Enable)
Electrification Output Enable is the electrification output control signal 'PWM-LOW ACTIVE'.
When MHV-PWM LOW signal is received, Q401 turns on and the steady voltage will be accepted to the non-
inverting terminal of OP-AMP 324. As the voltage higher than the inverting reference voltage of OP-AMP,
which is set to R405 and R406, OP-AMP output turns high. This output sends IB to the TRANS auxiliary wire
through current-restricting resistance Q402 via R408 and C403 and Q402 turns on. When the current is
accepted to Q402, Ic increases to the current proportional to time through the T401 primary coil, and when it
reaches the Hfe limit of Q402, it will not retain the "on" state, but will turn to "off". As Q402 turns 'off', TRANS
N1 will have counter-electromotive force, discharge energy to the secondary unit, sends current to the load
and outputs MHV voltage through the high voltage output enable, which is comprised of Regulation circuit.
U103 7407
MHV-PWM
R412 2.2K
R411 2K
5-5-7-5 BIAS (supply/dev/blade output unit)
BIAS (Electrification Output Enable) Electrification Output Enable is the electrification output control signal
'PWM-LOW ACTIVE'.When BIAS-PWM LOW signal is received, Q501 turns on and the steady voltage will be
accepted to the non-inverting terminal of OP-AMP 324. As the voltage higher than the inverting reference volt-
age of OP-AMP, which is set to R506 and R507, OP-AMP output turns high. This output sends IB to the
TRANS auxiliary wire through current-restricting resistance Q502 via R509 and C504 and Q502 turns on.
When the current is accepted to Q502, Ic increases to the current proportional to time through the T201 pri-
mary coil, and when it reaches the Hfe limit of Q502, it will not retain the "on" state, but will turn to "off". As
Q502 turns 'off', TRANS N1 will have counter-electromotive force, discharge energy to the secondary unit,
sends current to the load and outputs DEV voltage through the high voltage output enable, which is com-
prised of Regulation-circuit.
5V
R520
R501
26K
100 Q501
BIAS-PWM
A708-Y
2
CON03-#24
U103-A
R519
7407
2.2K
R503
100KF
R502
2K
WorkCentre Pro 412
Launch Issue
18V
R405 220K
Q401 A708
24VS
R403 130K +
R404
27K
R402
_
82K
C407
104
R406
2.2K
C503 R508
104
47K
R506
86.6KF
5
_
7
U1
+ R509
6
47K
U101-B
C501
R504
KA324
104
56.6KF
C502
R507
222
12KF
August 2001
T401
24VS
Q402
D526
R408 R409
47K 390
KA324
C403
333
24VS
D502
T201
4KV
KAB-007
7
1
C506
5 6
Q502
3KV 471
D526-Y
C505
2
2KV 680
4
R510
430
C504
R511
333
1W 3
Circuit Description
MHV OUTPUT
C404
3K/471
C406
D402
3K/471
4KV
R416 R413
15M 12M
OPC
R417
15M
ZD401
150V
R514
MGR1/2W 50K
BLADE
ZD501
R515
100V
MGR1/2W 50K
SUPPLY
ZD501
100V
R512
DEV
MGR1/2W 12MF
R516
MGR1/2W 50K
5-31