*
At rising of the CLPWM signal (V4), the coy lamp is switched by
the triac. The trigger signal Cl is sent to the triac to turn on the
lamp. Then the lamp is turned off at the zero-cross point of V1
waveform.
The CPU reads the control voltage level (QV) corresponding to the
change in the copy lamp voltage
The CLV produces the waveform equivalent to the copy lamp voltage
waveform which disables the full-rectified waveform of AC input
during the pulse ON time. The waveform is converted to the DC level
by the low pass filter composed of C102 and R105, and inputted to
the CPU. The relationship between the CLV and the pulse ON time is
shown in the figure below.
CPU output (CLPWM)
•
The shorter the pulse ON time is, the higher the CLV is, and vice
versa.
•
The pulse ON time rises at the zero-cross timing of AC and is
driven with duty.
•
Positive pulses the copy lamp ON signal are generated by C248
(C253) at falling of the CPU output and inputted to the photo triac
through the 2-stage transistors.
(11) Power section
This model is provided with the auto shut-off mode. The power sec-
tion is also designed for it. When the power switch of the copier is
turned on and the AC power is supplied, AC waveforms for +5V
power are generated in the secondary side of transformer T301. The
AC waveforms are full-wave-rectified and smoothed by diode BD102
on the main PWB side, and 5V is generated by 3-terminal regulator of
IC111. The 5V power is supplied to the CPU.
When the CPU is actuated by the 5V power, it starts the switching
power to output the SWPEN signal (CPU output: LOW). The switch-
ing power outputs voltages of 24V and VBS with this signal. BVS is
stabilized by IC112 to become a voltage with stable BV, and is used
for LED display. 24V is supplied to the motor and the solenoid, and
supplied also to the 3-terminal power for 5V through D144.
When the CPU turns off SWPEN to enter the auto power shut-off
mode, 24V and VBS output falls near zero, virtually turning off.
0V
0V
0V
0V
+5V
0V
0V
VCL
V5
V4
V3
V2
V1
a
b
8 or 10 msec
Pulse ON (Varies)
50Hz
60Hz
CLV
(V)
(msec)
Pulse ON time
T301
BD102
SINB60
C111
2200µF
IC111
7805
5V
C107
47µF
24V
GND
V8S
1SWPEN
D144
1N4004E
5V
DTC123JKA
Q209
IC101
CPU
IC112
7808
C106
47µF
8V
C105
47µF
Main switch
(MSW)
Main PWB
AC PWB
DC power unit
12 – 10
www.freeservicemanuals.info
1/11/16
Published in Heiloo, Holland.
