Muratec F-110 Field Engineering Manual page 66

4-4-2-8. 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 termi-
nal 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 volt-
age through the high voltage output enable, which is comprised of Regulation– circuit.
U2 7407
MHV-PWM
18V
Q401 A708
R411 2.2K
R403 130K
R404
27K
R402
82K
C408
R412 2K
104
R405 220K
24VS
R408
+
47K
_ KA324
R406
2.2K
T401
24VS
C404
3K/471
D402
4KV
Q402
D526
R409
390
C403
333
Circuit Description
MHV OUTPUT
C406
3K/471
R416
15M
R417
15M
4-33