Power Supply Board Section - Panasonic KX-FLB802CX Service Manual

Temperature AD value
[C°]
20 102
21 100
22 97
23 95
24 93
25 91
26 88

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.
AC
Input
Input
Circuit
A-B Voltage Wave Form
0
C-D Voltage Wave Form
0
E-F
G-H Voltage Wave Form
0
Heat Lamp
[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).
HEX reading Temperature
[C°]
66 67
64 68
61 69
5F 70
5D 71
5B 72
58 73
Block Diagram
A
Rectifier
+
Circuit
Kick-on
C5
B
Voltage
Circuit
R41
R4
R3
R2
Triac
SCR51
AD value HEX reading
30 1E
29 1D
28 1C
27 1B
27 1B
26 1A
25 19
T1
Surge
absorber
Converter circuit
Circuit
C
Q1
D
Control
Circuit
E
O.C.L
F
Error Detecting
Circuit
Photo Triac
Coupler PC2
67
KX-FLB802CX/KX-FLB812CX/KX-FLB802CXS/KX-FLB812CXS
Temperature AD value
[C°]
114 9
115 9
116 9
117 8
118 8
119 8
120 8
G
24V
+
3.3V
Output
3.3V
Circuit
12V
+
6V
+
DGND
PGND
H
PC1
HTRCTL
HEX reading
09
09
09
08
08
08
08