Hi, guys. New to the board with a couple questions

Discussion in 'General Electronics Chat' started by compuslave, Mar 29, 2011.

  1. compuslave

    Thread Starter New Member

    Mar 29, 2011
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    Hi, guys. I'm a home hobbyist with a ton of questions. At the moment I really only have two, though. First, I bought a usb power supply from sparkfun and want to mount it in an enclosure. The board has a small switch on it. It's not a three position switch, yet it has three leads soldered to the board (btw, this was a kit I assembled). I would like to use a different switch but the switch I have that I'd like to use only has two leads. What is the third lead for on the other switch?

    Second, I have some parts from some old hard drives I want to play with. I really want to play around with the armature. Where can I find info about the pinout? I just want to know which of the pins on the part that connects to the main board does what. I can trace the two wires of the voice coil back pretty easily, but the wires that go to the read/write heads aren't so easy to trace. Also I'd to read a little bit about how they work.

    Thanks, guys. If I hadn't worked 12 hours today and wasn't so tired I'd introduce myself a bit better. I gotta hit the hay, though.

    Thanks again!
     
  2. compuslave

    Thread Starter New Member

    Mar 29, 2011
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    Btw, in regard to the hdd pinout. I'm not talking about the pinout of the whole drive. Just the part that connects the armature to the rest of the hdd electronics.
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    A very common switch is the "Form C" type, which translates into having the following terminals: common, normally open, and normally closed. It's likely that the switch you're looking at is of that type. If I had my druthers, every switch I have would be of this type, regardless of the number of poles. But in high-volume manufacturing, it saves money to leave out one of the terminals if it's not going to be used.

    I worked in the hard disk industry in the 80's and, unless things have changed, it's unlikely you'll find the diagrams you need, as the hard drives were not things that would typically be serviced. Thus, there'd be no reason for the manufacturer to publish the wiring diagrams.
     
  4. compuslave

    Thread Starter New Member

    Mar 29, 2011
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    Thanks for the reply. I guess now I know what to google to help me rewire it with my new switch.
     
  5. BillB3857

    Senior Member

    Feb 28, 2009
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    Concerning the switch with three terminals, probably only two of the solder pads on the PC board will have traces going to other points on the board. These pads would be the ones you would want to use for installing an external switch. If, by chance, two of the three pads are soldered together, they are simply shorting the switch position that the switch would short in the OFF position.
     
  6. compuslave

    Thread Starter New Member

    Mar 29, 2011
    4
    0
    Thanks, that's what I needed to know. Funny, common sense should have told me that, but my common sense is on vacation.
     
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