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I have a Seagate ST3500620AS Harddrive that's just laying around and not being used. I want to power the motor at full speed (rated to run at 7200rpm) and do some hobby projects with it.

Problem is, I can't seem to get the harddrive to spin up. I have connected a SATA power cord to the harddrive and have connected yellow to 12V, red to 5V, the two blacks to ground. Yet I'm not getting any movement.

I've read various sources and found that it could be a variety of things 1)The motor is an AC motor, therefore needs AC voltage(some sources say it's a DC brushless motor) 2)The circuitry for the motor is fried, thus need to drive the motor sans the circuitry

What route should I take to get this motor spinning? Does anyone have experience in running newer internal harddrives externally? All I need it to do is spin at full speed.

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  • \$\begingroup\$ What makes you think the hard drive just sits there spinning when it's not being accessed by a computer? You're going to have to bypass all that control circuitry and power the motor directly. The voltage/current requirements are your best guess. Or, scope the lines and plug it into an external sata port. It'll spin up and then you'll know. \$\endgroup\$
    – Samuel
    May 27 '15 at 23:14
  • \$\begingroup\$ You need to do more than "connect power" to get a BLDC motor spinning. \$\endgroup\$ May 27 '15 at 23:16
  • \$\begingroup\$ Also you say "I see no movement"... That to me means you have taken something apart. There's so much that could have gone wrong there. If that's the case, even if the hard-drive is being polled for data or information the motor might not spin, because the electronics are now broken (maybe even due to overloading) or because they sense a difference somewhere, or because you tore a trace on the FCPCB. \$\endgroup\$
    – Asmyldof
    May 27 '15 at 23:19
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The Stepper motor in a harddrive will not run with power applied just to the logic board. The logic board needs to activate the motor through the SATA connection. If you want to power the motor at full speed, you need a stepper motor driver and connect it to the raw motor connections (by removing the logic board)

See Make hard drive stepper motor run 7200 rpm for a way to make it run.

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