How to test optical drive power?

six50joe1

macrumors newbie
Original poster
Oct 2, 2012
4
0
While trying to fix the upper drive door on my Mac Pro the other day from getting stuck during eject, I must have crimped a wire while trying to put the drive housing back in (I had it powered on since I needed to test the door opening). I heard a little crackle (like a damaged wire). I can't see any physical damage to the optical drive cable or power cable, but the drive no longer has power. I did replace the ribbon cable to the drive, but no dice.

Before I order a replacement for the power wire, is there an easy way to test that it has juice, without another optical drive?

Thanks in advance!
Joe:confused:
 

ActionableMango

macrumors G3
Sep 21, 2010
9,518
6,773
Use the power cable from the other optical bay to try to power your drive.

Or put your multimeter probes on the right contacts of the power connector to check for voltage.
 

six50joe1

macrumors newbie
Original poster
Oct 2, 2012
4
0
Thanks AM,
I'm assuming you mean one of those inexpensive things at Radio Shack with the two probes?
As I don't know which are the right contacts, is it safe to try it on different combinations of the 4 connectors? And if so, if I register power on any of them does it indicate that the cable is good?

Thanks again,
Joe
 

ActionableMango

macrumors G3
Sep 21, 2010
9,518
6,773
Well I'd just try the power connector from the other optical bay first.

What model/year Mac Pro is this?
 

six50joe1

macrumors newbie
Original poster
Oct 2, 2012
4
0
I think I bought it in 2008. It's a dual core 2.66ghz.

I haven't been inside it since my last post, but if by the connector for the other bay you mean the other connector on the same power cord, I'd already tried that.
 

666sheep

macrumors 68040
Dec 7, 2009
3,626
229
Poland
If you have a multimeter, measure current on each wire. It should be like below (4 pin one):



In MP All wires are black, but you'll know which one is which looking at the shape of the plug.
 

ActionableMango

macrumors G3
Sep 21, 2010
9,518
6,773
That's a great diagram.

OP, go to the shack and pick up that cheap multimeter. Set it to DC voltmeter mode.

Put the black probe on a ground and the red probe on the 5V line. MM should read 5V.

Do the same for the 12V line. MM should read 12V.
 

six50joe1

macrumors newbie
Original poster
Oct 2, 2012
4
0
Wow, ask and ye shall receive!

Thanks so much 666 and actionable, you just saved me the cost of a replacement cable and more disappointment. I did exactly as you instructed, and discovered that the power cable is fine.

That leaves only two things- the drive itself, or a problem on the motherboard itself, the latter of which would seem unlikely (and hopefully isn't the case).

As far as buying a replacement drive- even though I haven't proved this is where the problem lies- another question:

I may upgrade to another Mac Pro or Imac next year. If I do and want to trade in this Mac pro at gazelle.com, would you say the cost of replacing the drive will be more than the difference in trade in value I'd get, or the other way around?

Thanks much again,
Joe
 
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