Lately I've been elbows-deep in some broken Playstation 3's and found myself wanting to test their cooling fans. These have a three-wire header with leads colored brown, black, and gray; you may be tempted to conclude that this is a brushed DC fan with a tachometer lead, but you'd be wrong. These are brushless fans, and the third wire is a PWM signal that you supply to control the speed of the fan. The two PS3s (both “fat” style) I've opened recently have compatible fans from separate manufacturers; one is a Nidec G14T12BS2AF-56J14 and the other is a Delta Electronics KFB-1412H.
It's not trivially easy to find datasheets for these fans, but no matter. If you just want to test them or need a good centrifugal blower for one of your own projects, do the following:
- Apply 12 volts across the brown and black leads; +12 V on brown with return on black. The fan will probably jump a little but it won't start spinning.
- Drive the gray lead with a TTL-level pulse train at 25 kHz from a signal generator or 555 timer circuit or microcontroller or whatever.
- Control the duty cycle of this pulse train to adjust the speed.