Power supply missing switch, isn't turning on

[chaight]

I bought the reccomended power supply (the one from aliexpress) And it came without a switch between 110v and 220v (even though theres a hole for it and a spot on the pcb) It also looks slightly different from the pictures. When I power it up with AC wires (I checked the voltage with a multimeter and it was 120v) the led doesn't turn on and nothing is output on the V+ or V- screw terminals. Anyone have any advice? Or bought the same one and would be willing to tell me if mine is different?
Any help is greatly appreciated.

[HTheatre]

Hello chaight,

Refering me to the AC value you measured, I suppose that the voltage of the AC in your country is 110-120V.

By security, when you purchase one, the 115-230 VAC power supply comes setted on 230V. That could explain that you do not have any current at the power supply output.

Did you tried to contact the AliExpress' seller about the missing switch?

See ya.

[chaight]

Hi HTheatre, thanks for the reply. I live in Canada so 110V is normal here. I contacted the seller but all they asked for was proof it wasn't working (didn't say anything about the missing switch) by inspecting the PCB traces it looks like the middle pin of the switch is connected to the 220v side... Does this mean I can't change it into a 110v power supply?

[HTheatre]

Could you please take some pictures of the PCB? It must be possible to set it on 110V permanently, by shunting the AC selector switch.

[chaight]

Alright I will when I get home from work. If it is hardwired through the PCB there's no way to get around that right?

[chaight]

Here's a picture of the missing switch and how it's wired in on the PCB:
Thanks in advance for the help!

[HTheatre]

Hi chaight,

Just connect the tracks as shown on the picture with a piece of electric wire (16-18 AWG).



Your power supply is designed as on the picture below.



In 220V, the circuit must be open. The switch of the current's selection is OFF or ineffective. The two big capacitors are charged by a bi-alternating rectifier. The 4 diodes of the bridge are used and each capacitor supports only half of the DC voltage obtained thanks to the balancing resistors.

In 110V, the circuit must be closed. The switch of the current's selection is ON. The rectifier is then configured as a voltage doubler. Two diodes only (the left ones on the circuit' diagram) are used. Those on the right are inactive since they are in reverse mode when the cicuit is closed by the switch of the current's selection.

Thus the DC voltage across the two capacitors is approximately the same whatever the mains voltage, 110 or 220 volts.
As the switch of the current's selection is a two position slide switch, one of its pins, the one on the 220V side, is connected to nothing or not used. That is the case on your power supply, where the emplacements of 2 of the pins of the switch are located on the same PCB's track.

See ya

[chaight]

Wow thank you for the awesome reply. I'll try this tonight but I am worried if they missed the switch they also could've missed any resistors/other components. There are acouple of spots on the board where stuff is missing but it's probably just so that they can use the same board for multiple products right? I'm worried if I bridge that gap with wire but I'm missing a resistor or something it could be a fire hazard.

[HTheatre]

Hi chaight,

Yes, the PCB is surely used for several products or the power supply design has evolve, but not the PCB.

But if you are worried and for safety, once you have made the shunt, you can connect your power supply in the middle of the garage or in your garden using an extension cord. Note that is not so dangerous than overcharging Lion-Polymer batteries which can explode.

The risk would be greater if the power supply you had received was configured to operate under 110V and you lived in a country where the current is 220V.

See ya.

[chaight]

Thanks so much for your help HTheatre! It ended up working perfectly fine. Thanks for all you do in this community.