Author Topic: Another Cheap power supply :)  (Read 388 times)

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Offline jord4231

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Another Cheap power supply :)
« on: April 14, 2021, 10:47:25 am »
Just thought I'd share my recent experience with an eBay 20a 24v switch mode power supply.

I purchased this to use in my self playing piano project (if your interested you can see it here https://youtu.be/xp2ocvnNoJs (this was a progress video its since complete)

The power supply worked ok for a little while but just had no output all of a sudden it was not under much load at the time of failure.
On further investigation the two large NPN transistors have failed shorted.
It almost looks like the board has been wet at some stage (not in the time I've owned it) the dried crusty flux everywhere is a bonus :)
Photos almost don't do it justice but I'm sure you get the hint. Enjoy  :-DD
 

Offline MrMobodies

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Re: Another Cheap power supply :)
« Reply #1 on: April 14, 2021, 08:54:07 pm »


The placement of some of the components to me seem very similar to this other one torn down by Diodesgonewild:

https://www.eevblog.com/forum/dodgy-technology/new-powersuply-from-china-if-you-think-you-saw-it-all-unbelievable/msg3454624/#msg3454624





I wonder if they came out of the same factory or from the same designer.
« Last Edit: April 14, 2021, 09:04:52 pm by MrMobodies »
 

Offline amyk

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Re: Another Cheap power supply :)
« Reply #2 on: April 14, 2021, 11:49:06 pm »
Could be a common/reference design. 24V PSUs of that shape and power are not exactly a rare product.
 
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Offline AmnevaR

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Re: Another Cheap power supply :)
« Reply #3 on: April 15, 2021, 09:08:17 am »
Those power supplies are common as mud. You'd want to don't turn it on take it apart first  ;D
Watch out for solder balls! I've seen some of them stuck in flux or silicone near capacitors.


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