Canon NP-70 Service Manual page 78

NP -70
3-39
3.4 OUTLINE OF ELECTRICAL COMPONENTS AND CIRCUITS
3.4-1 SWITCHABLE TAPS FOR AC LINE VOLTAGE COMPENSATION (230VAC COPIERS-
EUROPE)
This feature is provided in two series of bodies (Product No. 8-11154 & 8-11155) to permit
the use of the copiers in countries with either 220V, 230V or 240VAC line voltage. Changes
in copier design or components used are not necessary due to inclusion of these compensation
taps (reference - 230VAC copier schematic).
3.4-2 AC LINE VOLTAGE FILTER (230VAC COPIERS -EUROPE)
In order to meet certain industrial standards, slow-pass filter is installed in two series of
bodies (Product No. 8-11154 & 8-11155). Fig. 3-5 depicts the schematic diagram of this
sealed unit.
0
F. L. T.
0
p LINE AC
Fig. 3-S Low-Pass Filter —Schematic Diagram
3.4-3
RECTIFICATION CIRCUIT CARD (ALL COPIERS)
O LINE AC
The conversion of the AC voltage stepped-down by the low voltage transformer (LVT) is
performed by the rectification circuit card. Part of this card includes the DC voltage regu-
lator, for which the following explanation is provided.
1) VOLTAGE REGULATOR -TYPICAL
If the output of the voltage rectifier is used as a direct power source, it will not be suffi-
ciently stable. Therefore, the rectified voltage output is applied to a voltage regulator to
produce a constant level DC voltage, as follows:
Difference
Amplifier
a) The output voltage Eo is compared with
the constant voltage Ez and, if there is
a difference between them, the latter is
amplified by the amplifier and applied
to the base of transistor Tr.
b) As a result, the transistor operates to
reduce the difference and produce a
regulated output.
Ei
0
Fig. 3-6
Voltage Regulator —Typical
© CANON INC.
Second Printing-June, 1974