Service manual

MFC-8420/8820D/8820DN, DCP-8020/8025D/8025DN
SERVICE MANUAL
3-9
1.3.14 Power supply
+5V is generated by the 3-pin regulator from astable 7V supplied from the LVPS. +5V is used
for the IEEE1284 interface, the LD PCB and the engine PCB. In addition, +1.9V is generated
by the 3-pin regulator from 3.3V supplied from the LVPS. +1.9V is used for the CPU within the
ASIC and the logic circuit.
+
+
+
+
+
VDD7
D2
RB751V-40
0V
VDD5
Q6
NJM2391DL1-19
OUT
VCC
GND
C157
C22
16V
C151
C104
FG1
OT1
C140
C10
16V
C158
C104
VDD7
0V
C141
C220
6.3V 6V
VDD3
B3B-EH
1
+3V
CN8
2
+7V
3
0V
C138
C220
6.3V 6V
VDD3
C128
C104
0V
VDD1.8
Q5
NJU7223DL1-19
1
OUT
2
VCC
3
GND
C137
C104
C125
C10
16V
D1
RB751V-40
LVPS
Fig. 3-16