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KX-MB2110RUW/KX-MB2130RUW/KX-MB2170RUW/KX-MB2117RUB/KX-MB2137RUB/KX-MB2177RUB
1.3.2.
SMPS (Switching Mode Power Supply) Section
Changed from the Original Service Manual section 6.18.
The power supply board circuit generates 24Vdc and 12Vdc.
It also supplies AC voltage to the halogen heat lamp in the fuser unit.
The power supply board uses the switching regulator method.
It also supplies AC voltage to the halogen heat lamp in the fuser unit.
The power supply board uses the switching regulator method.
[Input Circuit]
The input current goes into the input rectifier circuit through the filter circuit.
The filter circuit decreases the noise voltage and the noise electric field strength.
The filter circuit decreases the noise voltage and the noise electric field strength.
[Rectifier Circuit]
The input circuit is rectified by RC1 and charge C2 to make DC voltage.
Then it supplies power to the converter circuit.
Then it supplies power to the converter circuit.
[Kick-on Voltage Circuit]
Bias is applied to the Q1 gate via this circuit when the AC power is turned on and Q1 begins operating.
[Control Circuit and Error Detecting Circuit 1]
The control circuit detects the voltage that increased in an error detect circuit 1 and controls it to become the predetermined out-
put voltage.
This is shown as follows.
When the output voltage of the 24V circuit or 12V circuit increases, the current of the photo coupler PH1 increases, the pulse
width of the output control IC becomes narrower and the ON period of Q1 becomes shorter.
put voltage.
This is shown as follows.
When the output voltage of the 24V circuit or 12V circuit increases, the current of the photo coupler PH1 increases, the pulse
width of the output control IC becomes narrower and the ON period of Q1 becomes shorter.
[Over Current Protection (O.C.P)]
The highest drain current of Q1 is limited by a over current circuit. The 24V or 12V output is limited by this circuit.
[Over Voltage Protection (O.V.P)]
If the 24V or 12V output was increased, the VDD of control circuit also was increased.
The control circuit detects the increased VDD and controls it to becomes 0V.
The control circuit detects the increased VDD and controls it to becomes 0V.
Dummy load method (to quickly check the power supply output).
See the Low Voltage Power Supply Board (SMPS Board)Section.
Input
Circuit
Circuit
AC
Input
Input
RC1
VDD
G
H
24V
Kick-on
Voltage
Circuit
Voltage
Circuit
E
F
12V
HTRCTL
GND
Control
Circuit
Circuit
Converter
Circuit
Circuit
C
D
Rectifier
Circuit
Circuit
A
B
+
Error Detecting
Circuit PH1
Circuit PH1
O.C.P
O.L.P
Q1
A-B Voltage Wave Form
C-D Voltage Wave Form
E-F
G-H Voltage Wave Form
0
0
0
T1
Triac
CR1
CR1
Heat Lamp
Photo Triac
Coupler PHT1
Coupler PHT1
Block Diagram
+
+
C2
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