DANGEROUS POWER SUPPLIES

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This is a WARNING to buyers of HDD docking stations that use far eastern power supplies


Some of these supplied power units are badly constructed, have little or no protection fusing and can CATCH FIRE   they also have NO EMC protection and are surely illegal to use in most countries.

One item concerned was model LSD-001 the small 12Volt and 5Volt 2 Amp units used to power USB external hard drives, in cases, or with USB/SATA/PATA adaptors and Dockings.

Here is a document I wrote on the subject after a nasty experience with one.

 Destruction of switched mode power supply, supplied with HD docking station

Here is my hypothesis on the destruction of this small dual voltage switched mode PSU

These PSU's are constructed cheaply in the far east, they have inadequate fusing protection and no EMC noise filtering. The main active device, a power FET device is mounted on a small aluminium plate internal to the printed circuit board, it has no outward facing faces so all heat created by the power FET is retained in the plate, none is radiated to the outside which is a minimum requirement to keep the device temperature to a safe working level.

It is obvious to me from the melted solder on the connection pins of this device, that far too much heat built up within the device causing it to fail, this failure short circuited the 250V DC on the 47uF capacitor and resulted in the destruction of the 4 diode rectifier bridge this put the full AC mains across the capacitor and resulted in the vapourisation of the PCB tracks from the mains connector to the diode bridge, it also destroyed the fuse which should have been the first fail safe device, since there was no evidence of any wire left within the shattered fuse body, it is not possible to gauge it's current rating. 1 Amp is normal in this type of PSU. Certainly, judging by the thickness of the destroyed copper tracks, this fuse was not of a suitable rating.

I have included some pictures of the device (1) and some of the internals (3-6) described above,
also a picture of the illegal plug (2) supplied by an eBay seller with the docking station.

1.(PSU picture) 
  

2. (Illegal Plug)


3. (Burnt casing)


4. (Burnt PCB)


5.(PCB Top view) 


6.(PCB Damage)   


Don't Let this happen to you, check your Power supply NOW !

if it looks like the picture in (1) you could be in for a NASTY surprise.


Follow up information: October 15, 2009
Seeking a replacement of a better quality I put this question to a seller:

I am contacting you because I need a replacement for a HDD docking
station power unit. I had a nasty experience with one from Hong Kong,

Yours looks a better deal but can I ask you to read my guide, and
confirm your PSU does have proper EMC filtering and fusing?

The reply from the seller:

HI. Thank you for your enquiry. I do not think this power supply fits your
demand.

I conclude from this reply that for some reason the seller DID NOT want to sell me one?
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