Power Supply Board Section - Panasonic KX-MB2085CXW Service Manual

6.19. Power Supply Board Section

The power supply board circuit generates +7V 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 D7001, D7002, D7003 and D7004 and charge C7002 to make DC voltage.
Then it supplies power to the converter circuit.
[Kick-on Voltage Circuit]
Bias is applied to the Q7001 gate via this circuit when the AC power is turned on and Q7001 begins operating.
[Over Current Limiter (O.C.L)]
The highest drain current of Q7001 is limited by a limit current circuit. The 7V and 24V output is limited by this circuit.
[Over Voltage Circuit]
If the 24V output was increased, the VDD of control circuit also was increased.
The control circuit detects the increased VDD and controls it to becomes 0V.
Dummy load method (to quickly check the power supply output)
Refer to Power Supply Board Section (P.167)
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KX-MB2085CXW/KX-MB2090CXW