SATA Power Circuit Question.

V

Vapor1000

[H]ard|Gawd
Joined
Oct 8, 2004
Messages
1,047
I am redoing a project i undertook several months back where i tied an SATA's hard drive power Rocker on/off switch in order to have a form of hardware power control over the hard drive's on/off state.

I used a DPST switch to acomplish this supplying the 12v and 5v through the switch. However this next adventure i'm going to be partaking in involves about 10 drives powered in pairs to 5 rocker switches. And i would like to futureproof it a bit factor in for the possible yet unforseeable use of the 3.3v power line on the SATA power connector.

While i could use a 3PDT or 4PDT switch to acomplish this, the switch's cost is about 3-4 times the cost of a DPST or DPDT switch, and i would like to keep the cost of the project down to a minimum.

So here is the question. I know that a circuit is not complete without a ground wire. and the SATA power cable only runs 2 Ground wire's for the 3 Power Sources (12v, 5v, and 3.3v). However is it possible to damage the electronics having the 12v 5v and 3.3v always plugged in and turned on to the hard drive, but try to control the drive's power on/off state by controling the opening and closing of the ground wires on the cable?

So in less words "Will having the 12v, 5v, and 3.3v connected to the drive and powered without a ground wire present damage the hard drives?"
 
No one has any input as to if it is safe to control the on/off state of an SATA device by connecting/disconnecting the ground wires?
 
It's a BAD idea. Removing the ground from the power wiring will not turn off the drive, instead it will force the return current to flow through the ground of the signal wiring which was never designed to carry high currents.
 
How can you be sure the drive won't be grounded some other way, such as through the narrow data cable (has 3 ground wires) or through the chassis? Also isn't hot plugging/unplugging supposed to be done while the power cable is always plugged in?
 
plugwash said:
It's a BAD idea. Removing the ground from the power wiring will not turn off the drive, instead it will force the return current to flow through the ground of the signal wiring which was never designed to carry high currents.
Click to expand...

Good call, hadn't considered that. This is exactly the reason i posted as clearly i wasn't sure i had thought of everything yet.

3PDT switch it is!

larrymoencurly said:
Also isn't hot plugging/unplugging supposed to be done while the power cable is always plugged in?
Click to expand...

I cant say i follow what you mean by this question Larry.
 
3.3v is required by most SSD's nowadays I believe. Regular drives don't need it.

As he said though, he wants to future-proof it in case they require the 3.3v line in the future.
 
he wants to future-proof it in case they require the 3.3v line in the future.
Click to expand...

You are correct. That's my fault for reading a thread days ago then trying to comment today without rereading...
 
You must log in or register to reply here.
Back
Top