Short-circuited my brand new SMPS :-(

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H

hanair

Member
Joined 2005
#1
EDIT: This was user error. I was testing the SMPS like I would test a transformer -- in AC mode 🙂. Everything is working as expected!



I just received my SMPS from AliExpress and while trying to check the voltage its output pins got short-circuited accidentally.

This model is very popular in eBay and AliExpress, and attached is its picture from the seller's listing.

This SMPS is supposed to be 300W with main outputs +/-24V, and I shorted -24 V pin to 0 volt. I am hoping it is still repairable.
Can any one guess what might have blown by short circuiting the outputs?

(I posted this also in diysmps)

Thank you so much for your help!
 

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#2
Believe most if not all SMPS's have fuses in the outputs. May be physically hard to find as they are not obvious in looks, but usually there. Mostly soldered into the circuit like a resistor or cap, not often in a fuse holder.

Hopefully it is just a blow fuse if you can find it. Any schematic you can find should tell the story.

Regards,
Greg
 
#3
I have requested schematics from the seller, but I doubt they will provide one. I will try to identify all components on the output side to see if anything stands out. I am not sure if shorting the output can cause any damage to the primary side
 
#5
Some PC units have a thermal fuse which resets after some time.
See if it happens.
And if it is no name Chinese, scrap it, buy a reputed one like Meanwell.
They use Japanese capacitors, original ICs and transistors.
Very well made.
 
#7
Any SMPS worth its salt should self-protect in response to a short and recover when the short is removed. This can be problematic in the case of low power auxiliary outputs ( a fuse or PTC would be a consideration in that case), but the main outputs should be short circuit protected, at least via the primary peak current limit protection.
 
#8
NareshBrd said:
Some PC units have a thermal fuse which resets after some time.
See if it happens.
And if it is no name Chinese, scrap it, buy a reputed one like Meanwell.
They use Japanese capacitors, original ICs and transistors.
Very well made.
Click to expand...

IMG_8256.jpeg

My koi pond controller mean well following a date with rain ingress shorting the ±12V/245Vac..

It blew the fuse in the line the pond distribution box and the PCB mounted fuse "FS1" next to the AC power but also cracked one of the ceramic caps and scorched PCB and probably destroyed transformer.

The circuit plugged into it (the controller) worked fine with a separate 12V supply after - so it's design protected the next circuit along. Hence I'm a meanwell fan.
 
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#15
Does this mean yours is blown?
Look at the 48 V supplies on the Meanwell website, and check what your equipment needs, a 24 V unit will not like 48 V when connected, and unless it is an amp, the voltage is high.
And if it is an amp, the current is on the lower side.
 
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