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Re: Swapping Drives - Sanity Check




On Saturday, February 23, 2019 10:52:20 AM Pascal Hambourg wrote:
> Le 23/02/2019 à 15:41, rhkramer@xxxxxxxxx a écrit :
> > On Saturday, February 23, 2019 07:53:23 AM Pascal Hambourg wrote:
> >> Le 23/02/2019 à 08:53, David Christensen a écrit :
> >>> Understand that if you disconnect the power cable to a motherboard,
> >>> drive, peripheral, etc., but not all the other cables (e.g. SATA
> >>> cable), you can fry electronics.
> >> 
> >> Right. This is why power pins are longer than data pins in plug&play
> >> connectors, so that they are connected first and disconnected last.
> 
> Oops, I meant "hotplug connectors".
> 
> > Hmm, that surprises me -- I guess I would have expected that you want the
> > data pins connected first (while no power is applied), and disconnected
> > last (again, while no power is applied).
> 
> Why would you want this ? From an electrical or logical point of view,
> it makes no sense.

Well, two reasons:

   * in most cases (other than hot plug) you want to make connections first, 
before you turn on the power  (I mean, for example, you don't assemble your 
computer with the power on)

   * and somewhat similarly (but in a very different context) in a 3 pin power 
plug for an ordinary household outlet (in the US), the ground pin is longer 
than the power pins so that the ground is connected before power is applied.