Xerox WorkCentre Pro 412 Service Manual page 101

Circuit Description
5-7-7-4 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 aux-
iliary 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 cur-
rent to the load and outputs MHV voltage through the high voltage output enable, which is comprised of
Regulation circuit.
5-7-7-5 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 refer-
ence voltage 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 primary 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 sec-
ondary unit, sends current to the load and outputs DEV voltage through the high voltage output enable,
which is comprised of Regulation-circuit.
WorkCentre Pro 412, FaxCentre F12 & 3/03 5-63
WorkCentre M15/M15i