Panasonic KX-MB2571RU Service Manual ▷ View online
49
KX-MB2571RU
6.8.6.
2W1-2 phase excitation
1. Timing chart
2. Wave form
CLKCD
(Pin46_IC701)
COUT1
(Pin52_IC701)
ADF Motor
current*
Fig. 6
5V/Div
10V/Div
0.5A/Div
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KX-MB2571RU
6.9.
FAN Motor Section
6.9.1.
General
This unit is equipped with FAN motor to prevent the developing devices, Low Voltage Power Supply board (SMPS Board) and other
devices from overheating during printing.
The FAN rotates at high speed (Approx. 3000rpm) while printing.
After printing is finished, FAN rotates at low speed (Approx.2200rpm) while predetermined period.
devices from overheating during printing.
The FAN rotates at high speed (Approx. 3000rpm) while printing.
After printing is finished, FAN rotates at low speed (Approx.2200rpm) while predetermined period.
6.9.2.
Circuit Diagram of FAN
FAN motor is controlled by following one circuit.
6.9.3.
Fan Control
For the control of FAN speed, comparator IC (IC504) is used.
This IC compares (+) side input level and (-) side input level.
If (+) side input level is bigger than (-) side input level, output of this IC is "OPEN".
If (+) side input level is less than (-) side input level, it outputs "L" level.
This IC compares (+) side input level and (-) side input level.
If (+) side input level is bigger than (-) side input level, output of this IC is "OPEN".
If (+) side input level is less than (-) side input level, it outputs "L" level.
6.9.3.1.
Half Speed Mode
In half speed mode, IC300_pin L2 outputs pulse (frequency is about 30KHz, duty is about 37.5%).
This pulse is integrated by R628 and C538 then Pin2_IC504 becomes approx. DC1.24V. Input level of IC504_pin2 is determined by
the voltage of between R590.
If voltage between R590 is less than 1.24V, output of pin1_IC504 becomes "H".
Then Q526 are turned on. So voltage between R590 (=the voltage of pin2_IC504) rises gradually.
When the voltage between R590 exceeds 1.24V, output of pin1_IC504 becomes "L".
Then Q526 are turned off. So voltage between R590 falls gradually.
By repeating these sequences, voltage between R590 is controlled approx. 1.24V.
On the other hand, if FAN voltage is represented Vo and voltage between R590 is represented VL, VL is determined as below for-
This pulse is integrated by R628 and C538 then Pin2_IC504 becomes approx. DC1.24V. Input level of IC504_pin2 is determined by
the voltage of between R590.
If voltage between R590 is less than 1.24V, output of pin1_IC504 becomes "H".
Then Q526 are turned on. So voltage between R590 (=the voltage of pin2_IC504) rises gradually.
When the voltage between R590 exceeds 1.24V, output of pin1_IC504 becomes "L".
Then Q526 are turned off. So voltage between R590 falls gradually.
By repeating these sequences, voltage between R590 is controlled approx. 1.24V.
On the other hand, if FAN voltage is represented Vo and voltage between R590 is represented VL, VL is determined as below for-
mula.
VL=Vo*R590/(R589+R590)
Vo=VL*(R589+R590)/R590
Since each value is as follows, Vo is determined approx. 9.7(V).
VL=1.24(V), R589=150(Kohm), R590=22(Kohm)
Vo=1.24*(150K+22K)/22K=9.7(V)
Vo=1.24*(150K+22K)/22K=9.7(V)
Therefore by reducing the voltage of FAN power supply, FAN rotates with half speed.
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KX-MB2571RU
6.9.3.2.
Full Speed Mode
In full speed mode, IC300_pinL2 outputs constant 3.3V.
When Q526 are turned on, Vo becomes approx 20V (approx.4V drops between R616, R617).
So the voltage between R590 is determined as follows
When Q526 are turned on, Vo becomes approx 20V (approx.4V drops between R616, R617).
So the voltage between R590 is determined as follows
VL=Vo*R590/(R589+R590)=20*22K/(150K+22K)=2.5(V)
Since IC504_pin2 is 3.3V and IC504_pin3 is 2.5V, pin1_IC504 is always "L".
Consequently all Q526 are always turned on, and then approx 20V is supplied to FAN motors.
Therefore FAN rotates with full speed.
Consequently all Q526 are always turned on, and then approx 20V is supplied to FAN motors.
Therefore FAN rotates with full speed.
6.9.3.3.
FAN stop
When IC300_pinL2 is "L", Q526 is turned off, then FAN stop rotation.
6.9.3.4.
Rotation detect signal
During the FAN rotation, the pulse signal is output from pin 2 of FAN motors as the rotation detects signals.
If the period of the pulse is wider than predetermined value, it is judged that FAN error occurred.
Then display shows "Call Service 4".
If the period of the pulse is wider than predetermined value, it is judged that FAN error occurred.
Then display shows "Call Service 4".
6.9.4.
Control table
FAN1ON
(IC300_pin
L2
)
FAN Mode
H
Full speed
Pulse
Half speed
L
Stop
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KX-MB2571RU
6.9.5.
Waveform
3.3V
3.3V
3.1V
0.6V
0.6V
24V
20V
30KHz
3.3V
1.2V
1.2V
0.6V
0.6V
12V
9.8V
(1)Full speed (H:20usec/Div)
Point D(1V/Div)
Point C(2V/Div)
Point B(2V/Div)
Point A(2V/Div)
Point F(5V/Div)
Point E(10V/Div)
Point D(1V/Div)
(2)Half speed (H:20usec/Div)
Point D(1V/Div)
Point C(2V/Div)
Point B(2V/Div)
Point A(2V/Div)
Point F(5V/Div)
Point E(10V/Div)
Point D(1V/Div)
Ground level
Ground level
Peak Level
Peak Level
Ground level
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