3-36V 60W adjustable switching power supply KJS-1509
(Reverse Engineered Schematics)
Schematic of a dubious adjustable switching power supply 3-36V "60W" type KJS-1509 Kejiesheng (except the voltmeter module). Flyback topology. The input voltage is mains 100-240V~ 50/60 Hz. The power supply overheats significantly and the maximum current it is able to supply drops significantly with temperature. Output high frequency ripple at 2A load is over 5 Vpp (!!!). The adjustment potentiometer is very non-linear, lower voltages are tricky to adjust. The insulation in the transformer is insufficient, risk of the mains voltage getting into the output. The switch built into the potentiometer may not even be designed for mains voltage. The power supply does not state the maximum current at all, only the power of 60W, but at what voltage? Once warmed up, simply never. Only 36W. The 22 ohm resistor in the secondary diode snubber measures open circuit. The real range of regulation is 3.59 - 35.9V. The control chip is probably OB2263MP.
Adjustable switching power KJS-1509 3-36V 60W - top
Adjustable switching power KJS-1509 3-36V 60W in a box damaged in shipping
Adjustable switching power KJS-1509 3-36V 60W - bottom
KJS-1509 - demonstrating the non-linearity of the adjustment. The marks are in 4V steps.
KJS-1509 (3-36V 60W) PCB board - top side
KJS-1509 (3-36V 60W) PCB board - bottom side
The voltmeter module circuitboard after desoldering the YX3361-65AR LED display (it only has 6 pins, so it must be Charlieplexed). The microcontroller is unmarked.
A video about this power supply
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