Hard drive motor

I've pulled apart doaens of 3.5" HDDs recently, just to get rid of all the old 0.5 GB clunkers around just taking up space. I was taking a few parts off the MB, but now I just scrounge the magnets, some phillips screws, and little else. Most of these drives are Maxtors. I've only pulled apart one 2.5" HDD. Here are some of my observations.

There are just a few companies making the motors, one common one is NIDEC. Some motors are permanently glued into the drive case, and can't be removed as a unit. No matter if they're removable or not, they're a bitch to get apart because they're glued together.

I see mostly four terminals on them, three for the phases and a common, so it might be seen as a 'Y' configuration. Some have a couple more terminals, apparently for a tachometer. I guess the four terminal ones use the output of a head to determine the speed, along with the head position.

Older drives may have used a separate chip to drive the motor, but I think the trend has been to cram as much circuitry into a single chip as possible so that newer drives have the motor driver combined with many other functions. If so, then you'll have to roll your own to make the motor run.

Many of the old Maxtors can be disassembled with a #1 phillips, but most of the newer and other drives require a #9 or #8 Torx and sometimes a smaller Torx. So you may have to swing by a hardware store and pick up a couple Torx bits for your changeable-tip magnetic screwdriver.

I found the KSH210 which is on many MBs is a low Vce(sat) PNP transistor that works well for the B.O.s if you're willing to put up with the upside-down PNP config.

I've found that the motors will light up the red LED connected across the coils very brightly. But it takes a quick spin to get the voltage high enough. Basically this proves that the motor has permanent magnets. I also connected a red LED across the drive terminals of the 'voice coil' that drives the heads, and swinging it mack and forth will light up the LED brightly.

Oh, one other thing. If you take off all four corners of the cover, and the cover doesn't pull off easily, then there's another screw or two hidden under the label that you have to remove. Poke around with the torx until you find it/them.

Watch your fingers! Those super magnets can snap together with so much force that they'll pinch you.

Have fun.

Thanks, Watson. Exactly as you described. Now for my next trick - I have 4 memory "sticks" (or whatever you call them) (modules ?) from an old 433 machine: 3 with 128 mb and 1 with 64 mb. Do you know of any place I could donate them? They are going to the trash can (I hate that) unless I can find somone to give them to. You're good with salvaged parts, so I figure you might know. They are free to whomever wants them.

Ed

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Donate them to Mike Terrell.

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Of the many HDDs I've disassembled, most have motors made by NIDEC, and these have four terminals. I measured these and found that the resistances indicated three windings connected to a common terminal in a "Y" configuration. So it would need three phases to drive it.

Thanks! Mailed them to him today.

Mine is a delta configuration - 3 wires with 5 ohms between each wire. If I want to drive it, I'll have to come up with a 3 phase generator or use a PIC to come up with

Ed