Panasonic KX-FLB802CX

67
KX-FLB802CX/KX-FLB812CX/KX-FLB802CXS/KX-FLB812CXS
6.18. POWER SUPPLY BOARD SECTION
The power supply board circuit generates +3.3V, +6V, +12V and +24Vdc. 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.
[Rectifier Circuit]
The input circuit is rectified by D10 to D13 and charge C5 to make DC voltage.
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.
[Surge Absorber Circuit]
This circuit is for absorbing surge voltage generated by the transformer.
[Over Current Limiter (O.C.L)]
The highest drain current of Q1 is limited by a limit current circuit. The 24V output is limited by this circuit.
[Over Voltage Circuit]
If the 24V output increases because the error detecting circuit or control circuit is broken, Control circuit will recognize this signal
and output becomes 0V. D104, D275 and D503 also prevent over voltage.
[3.3V Output Circuit]
This circuit is composed of DC-DC converter method.
Dummy load method (to quickly check the power supply output)
Refer to POWER SUPPLY BOARD SECTION (P.189).
20 102 66 67 30 1E 114 9 09
21 100 64 68 29 1D 115 9 09
22 97 61 69 28 1C 116 9 09
23 95 5F 70 27 1B 117 8 08
24 93 5D 71 27 1B 118 8 08
25 91 5B 72 26 1A 119 8 08
26 88 58 73 25 19 120 8 08
Temperature
[C°]
AD value HEX reading Temperature
[C°]
AD value HEX reading Temperature
[C°]
AD value HEX reading
Input
Circuit
AC
Input
C5
G
H
12V
24V
Kick-on
Voltage
Circuit
E
F
3.3V
6V
DGND
HTRCTL
PGND
Control
Circuit
R2
R3
R4
R41
Converter
Circuit
C
D
Rectifier
Circuit
A
B
+
Error Detecting
Circuit
Surge
absorber
circuit
O.C.L
Q1
A-B Voltage Wave Form
C-D Voltage Wave Form
E-F
G-H
Voltage Wave Form
0
0
0
T1
PC1
Triac
SCR51
Heat Lamp
Photo Triac
Coupler PC2
Block Diagram
+
+
+
3.3V
Output
Circuit