Chinese (lack of) quality.

Linear power supplies are something many of us use in the ham shack.  As well as being RFI-quiet, albeit very inefficient PSUs for our radios, smaller units are also useful for quietly powering other equipment, such as Raspberry Pi computers and the like.

Badged linear PSUs like this are widely available online.

 

I bought a generic linear PSU for computer use recently, but it never actually provided any output.  The seller on E-bay was decent enough to refund the price in full, and didn't want it back.  

I had a look at the PSU before dismantling and recycling its component parts last evening.  There was no immediately-obvious failure of anything.  The soldering quality was pretty dire, so I had a go at resoldering several contacts.  

Still no output.

I then dismantled the front controls panel board, where I immediately found at least one cause of the problem:

Hmm!  No wonder there was no output!

 

As you can see, two of the four potentiometers had snapped clean in two!  I'm not entirely sure how this happened during manufacture, but it may be because the board is first secured using the controls at either end, then tightening the centre two controls.  Even so, there should be more than enough 'give' in the solder legs, and even enough strength in the plastic body of the pot to take the strain.

Well, that is the trouble with Chinese manufacturing quite often: poor quality control.