Hard Drive Switch

R

Raxxath

Limp Gawd
Joined
May 29, 2007
Messages
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I have a rig in which I only want to power up one hard drive at a time, out of two drives. Currently I have this accomplished by simply switching the power cable between the drives, but I'd like to make it easier and faster(we all know what a pain molex connectors can be).

I really don't know a whole lot about about wiring and electronics. Could I use something like this with the drives, or do they require something stronger than a cathode switch? What would you guys recommend?
 
Well, that switch won't do. The drive would most likely die, since you'd be only taking away 12v and 5v would remain live. Then again it might not die, but it's a risk I wouldn't take.

Some hotswap bays designed to fit into PC cases would work, but you would not be able to do hot swap power, of course. Some are powered by key switch, which would be perfect for you. Turn the machine off, turn one drive off and another on by key, then turn the machine back on.

SATA is supposed to be hot swappable on most controllers, but you need the 3.3v line plugs, not the molex adapted ones. I assume you are talking about IDE though, since you mentioned molex connectors.
 
A Douple-Pole, Double-Throw switch is what you need. If you can find a DPDT keyswitch, that would be best. You probably don't want to be switching power from one drive to the other while the machine is running :) newark has one. The reason you want double-pole is so that you can switch both the 12V and 5V lines at the same time. It's ok to leave the GND connected.
 
=ACID RAIN= said:
Well, that switch won't do. The drive would most likely die, since you'd be only taking away 12v and 5v would remain live. Then again it might not die, but it's a risk I wouldn't take.

Some hotswap bays designed to fit into PC cases would work, but you would not be able to do hot swap power, of course. Some are powered by key switch, which would be perfect for you. Turn the machine off, turn one drive off and another on by key, then turn the machine back on.

SATA is supposed to be hot swappable on most controllers, but you need the 3.3v line plugs, not the molex adapted ones. I assume you are talking about IDE though, since you mentioned molex connectors.
Click to expand...

Actually, they're both SATA drives, I just used SATA power to molex cables to make things a little easier while manually switching power between them all the time. Both drives are suspended, so hotswap bays aren't an option.

Mohonri said:
A Douple-Pole, Double-Throw switch is what you need. If you can find a DPDT keyswitch, that would be best. You probably don't want to be switching power from one drive to the other while the machine is running :) newark has one. The reason you want double-pole is so that you can switch both the 12V and 5V lines at the same time. It's ok to leave the GND connected.
Click to expand...

Like I said before, I really don't know much about the specifics of wiring. Or soldering for that matter. :(

Are there any guides to properly wiring things like that? I was hoping for some simple, pre-wired switches, even if it meant having to use one for each drive, rather than one to control both.
 
If you look at the bottom of a standard DPDT switch, you'll see six tabs arranged in two rows, like so:
Code: 
| |
| |
| |
The middle tabs get connected either to the two tabs on one end, or the two tabs on the other end, depending on which way the switch is facing. In addition, each row is isolated from the other. You'll connect it more or less like so:
Code: 
 To HD1 12V <--| |--> To HD1 5V
12V from PSU ->| |<--5V from PSU
 To HD2 12V <--| |-->To HD2 5V
(BTW, Yellow is 12V, and red is 5V)
 
That would be perfect, because it makes the drives mutually exclusive. One can be on, or the other can be on, but not both at the same time.
 
Thanks Mohonri, that's a great diagram. Now, do I solder the ends of the wires to the switch, or is there another way? And what exactly do I do with the ground wires from the drives and PSU?
 
The ground wires can remain connected to the drives all the time. You'll have to break out the wire cutters, wire strippers, and soldering gun for this one. Actually, I'd suggest you buy one of these so you're not hacking up your PSU's cables.
 
Another option to avoid soldering is to use lug connectors that match the switch's connections. This is usually only an option for the larger switches. This page shows the sort of thing I mean - top photo on the left. The switch has to have flat lug blades on the bottom that the spade slides onto (similar to the top photo on the right). This will replace soldering with crimping.

I agree with Mohonri - use an adapter so you don't mess with the PSU wires directly.
 
I found some DPDT toggle switches at McMaster's... what do you guys think of # 7343K263? The 6 amp version is enough, rather than 15, correct?

They offer it with screw terminals, meaning I would simply expose the metal wire, wrap it around the screw, and tighten, right? No soldering required? :D
 
It depends on the type of screw terminal (some types of screw terminals don't even require the "wrap" part--you just stick the wire in a hole and tighten a screw), but I believe you are correct. However, I think that #7343K273 is slightly better suited for your purpose. The one you listed is an on-off-on switch, which means that it has three positions. In the center position, neither hard drive would get power. That *might* be what you want, but I'm guessing it's not, and that you want a two-position switch (on-on). There's no cost difference between the two, so it's your choice.
 
Mohonri said:
It depends on the type of screw terminal (some types of screw terminals don't even require the "wrap" part--you just stick the wire in a hole and tighten a screw), but I believe you are correct. However, I think that #7343K273 is slightly better suited for your purpose. The one you listed is an on-off-on switch, which means that it has three positions. In the center position, neither hard drive would get power. That *might* be what you want, but I'm guessing it's not, and that you want a two-position switch (on-on). There's no cost difference between the two, so it's your choice.
Click to expand...

That's good to hear.

And just to be perfectly clear, the molex connectors from the drives with only the grounds left in them should be plugged into the PSU, correct? And it doesn't matter if the PSU molex connectors are only grounds as well, or with 5v and 12v too, right? I just want to be certain I won't fry my drives from a stupid wiring mistake. :p
 
All the black wires inside your case are the same, if that's what you're asking. Let's assume you start off with the Y cable. You'll leave all the black wires intact, and only cut the red and yellow wires. And you'll connect those yellow and red wires to the switches.
 
Mohonri said:
All the black wires inside your case are the same, if that's what you're asking. Let's assume you start off with the Y cable. You'll leave all the black wires intact, and only cut the red and yellow wires. And you'll connect those yellow and red wires to the switches.
Click to expand...

I'm actually not using a Y cable, I suppose that's what was confusing me. I'll show you what things currently look like:

P1010155.jpg


You can see the two suspended drives and the sata to molex cables coming from each. I was manually switching the molex cable from the PSU between them, but pins kept popping out, and it was just a pain.

With the DPDT switch, I'm going to take the red and yellow wires from each drive cable, and from one PSU molex cable, then plug them all into their proper places on the switch. Then I'm left with three molex connectors with only grounds in them. What do I do with them, exactly?
 
I wired up the switch and everything today, and just tried to turn it on. The lights, fans, and even the proper hard drive turn on, but there's nothing showing up on the screen. I already reseated the video card and checked all the cables.

There's an orange wire included in the sata to molex cable that's apparently a 3.3v line. People seem to say that its not used at all, so I didn't use it either. Could that be my problem?

EDIT: Nevermind, just my sound card being stupid. Everything works great.
 
Great Project man. I like the fool-proof double booting idea. I assume your basically dual-booting with this setup.

No need to deal with boot loaders that way. I approve.
And I'm glad it worked out for ya.
 
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