At 08:35 AM 9/18/2014, Dale Snell wrote: >On Wed, 17 Sep 2014 14:30:18 -0700 >"Loren M. Lang" <[email protected]> wrote: > > > I'm assuming the power supply voltages are out of > > spec so I pulled out my voltmeter. Measuring the SATA power connector > > with the dead hard drive attached and Mac powered on, I found 5V on > > the 5V supply lines and no voltage on the 12V or 3.3V lines. No > > indication of something that might kill a logic board, but I would > > expect to see 12V on the supply. > >Okay, this is wrong. There should be a +12V supply at the drive pins. >It's not surprising that there isn't a +3.3V logic supply. Most >drives don't use it, so most manufacturer's don't provide it. >However, the 12 volt supply is required, and should always be >there. Did you measure the voltages with the drive plugged in or >not? The presence or absence of a load can make quite a >difference.
My laptop drive is labeled 5v 800ma, while several of my full size drives are labeled like this: 5v, 0.5A, +12v 0.33A. Are we sure laptop drives use 12v? Thanks JK >Also, did you check for an AC component on the supply pins? Or >better yet, use an oscilloscope on them? It's entirely possible >to have high-amplitude AC coming out of the power supply, yet >still have it read the proper DC voltage with a meter. That sort >of thing can fry your logic board. (Heed the Voice of Experience, >my son.) > >Hope this helps. > >--Dale > >-- >Imagine if every Thursday your shoes exploded if you tied them the >usual way. This happens to us all the time with computers, and >nobody thinks of complaining. > -- Jeff Raskin > > >_______________________________________________ >PLUG mailing list >[email protected] >http://lists.pdxlinux.org/mailman/listinfo/plug _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
