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 Post subject: Reliable HDD enclosure brands?
PostPosted: August 7th, 2014, 8:37 
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Joined: October 7th, 2012, 1:32
Posts: 36
Location: Westerndigi
Hi people, what are the quality HDD enclosure brands out there? Most of the manufactures of HDD appears to be Chinese ones, and I've been using some of them. The quality is rather shoty and there seems to be some critical designing flaws, for example, the power-supply is not grounded so every time you attach the data chord to the comp, there is a spark possibly caused by electro-static discharge between the plug and the case of my comp, kinda scary and it may have fried all of my USB ports.

I googled and googled and found only Chinese ones... any alternatives?


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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 7th, 2014, 10:47 
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Joined: August 13th, 2008, 13:10
Posts: 811
Location: World
Good question

I like metal cases because difuse better heat
But i did not think un electrónica questions


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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 8th, 2014, 7:09 
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Joined: August 26th, 2012, 19:18
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Location: England
Quote:
...the power-supply is not grounded so every time you attach the data chord to the comp, there is a spark possibly caused by electro-static discharge between the plug and the case of my comp


Are you saying there IS actually a spark - you can see it spark when you plug it in ?
Which part, if any, is sparking ?

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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 8th, 2014, 14:34 
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Joined: September 8th, 2009, 18:21
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The spark isn't due to ESD.

There is a Y2 capacitor between the "hot" AC side of the supply and the "cold" DC side. This results in the negative DC terminal sitting at a potential above ground, usually half the AC supply. If you measure the voltage between DC negative and AC ground, it could be of the order of 60VAC or 120VAC, depending on the locale. The capacitor's impedance is very high so this voltage won't shock you, although it might give you a surprise. I have heard that devices may be damaged under some circumstances, though. You can eliminate the risk by equalising the potentials before switching on the adapter. If you don't this, then the Y2 capacitor will discharge into your USB port.

Here is a photo of the PSU section in a DVD recorder:
http://www.users.on.net/~fzabkar/DVD/TD ... os/PSU.jpg

Notice the two capacitors just above the fuse at the LHS. There is a third capacitor to the left of the transformer. These caps straddle a horizontal demarcation line that separates the hot and cold sides of the board. Since the appliance has a two-pronged AC cord, the DC "ground" on the PCB floats to a level of around 120VAC. In fact the tingle is quite annoying.

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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 8th, 2014, 21:30 
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Joined: August 26th, 2012, 19:18
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Location: England
apologies to OP, perfect description of what happened, completely misread by me, even after quote :/

aside, and laughably, reminded me of a (UK) Radio 1 DJ phone in

DJ: and over to line 1 .. Hi who's on Line 1?
Listener: Hi Gary, it's Dave from Birmingham
DJ: Hi Dave, and where are you from?

#facepalm

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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 10th, 2014, 18:06 
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Joined: October 7th, 2012, 1:32
Posts: 36
Location: Westerndigi
digitalferret wrote:
Quote:
...the power-supply is not grounded so every time you attach the data chord to the comp, there is a spark possibly caused by electro-static discharge between the plug and the case of my comp


Are you saying there IS actually a spark - you can see it spark when you plug it in ?
Which part, if any, is sparking ?


Yes, unbelievable as it is, I can see actual spark. Ever short a 1.5 v battery and saw sparks? You get the idea.


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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 10th, 2014, 18:19 
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Joined: October 7th, 2012, 1:32
Posts: 36
Location: Westerndigi
fzabkar wrote:
The spark isn't due to ESD.

There is a Y2 capacitor between the "hot" AC side of the supply and the "cold" DC side. This results in the negative DC terminal sitting at a potential above ground, usually half the AC supply. If you measure the voltage between DC negative and AC ground, it could be of the order of 60VAC or 120VAC, depending on the locale. The capacitor's impedance is very high so this voltage won't shock you, although it might give you a surprise. I have heard that devices may be damaged under some circumstances, though. You can eliminate the risk by equalising the potentials before switching on the adapter. If you don't this, then the Y2 capacitor will discharge into your USB port.

Here is a photo of the PSU section in a DVD recorder:
http://www.users.on.net/~fzabkar/DVD/TD ... os/PSU.jpg

Notice the two capacitors just above the fuse at the LHS. There is a third capacitor to the left of the transformer. These caps straddle a horizontal demarcation line that separates the hot and cold sides of the board. Since the appliance has a two-pronged AC cord, the DC "ground" on the PCB floats to a level of around 120VAC. In fact the tingle is quite annoying.



If it helps:

The spark cause my MacBook pro to shutdown the screen, blackout for a while, then back to normal.

I found an "easy fix" (mihgt not be a fix at all) by connecting the data cord first, plug the plug in the socket, then the DC cord to the enclosure, and no above mentioned phenomenon observed.

If I didn't know better, there should be a chip to limit the current of host side to 500mA. But I'm not sure about the slave side.

Also, " You can eliminate the risk by equalising the potentials before switching on the adapter. " how do I do that?

Thank you for your help.


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 Post subject: Re: Reliable HDD enclosure brands?
PostPosted: August 10th, 2014, 18:53 
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Joined: September 8th, 2009, 18:21
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Location: Australia
Nicki2012 wrote:
I found an "easy fix" (mihgt not be a fix at all) by connecting the data cord first, plug the plug in the socket, then the DC cord to the enclosure, and no above mentioned phenomenon observed.

Also, " You can eliminate the risk by equalising the potentials before switching on the adapter. " how do I do that?

By doing exactly what you've done. :-)

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