Save money by replacing 3.5-inch drives yourself

Those 3.5-inch disk drives don't fail often, but when they do, you don't have to spend a bundle on a service call. Jeff Davis explains how to do the job yourself.

Recently, a consulting client asked me to do some hardware troubleshooting. The "device not ready" error was coming up every time a user tried to open a file on a disk in drive A. (In this shop, users keep copies of everything on floppy disks.) I ended up replacing the drive.

If you're someone who's never built or repaired a system, you might be tempted to pay for a repair. But take this tip: You can replace a 3.5-inch drive yourself.

Diagnosis: Transplant
Before I made the decision to replace the drive, I opened the case and checked to make sure the cables for that drive were in place and snug. I also used a can of air to blow the dust bunnies out of the drive.

On the software side, I made sure the device was visible under Device Manager. I deleted the drive, and Windows appeared to recognize and reinstall it. I tried reading multiple diskettes. For no apparent reason, the system couldn't read the drive.

Occasionally I've been able to get rid of the "drive not ready" error simply by cleaning the drive. This time, however, I didn't have any of the special cleaning disks and neither did the client.

So we made the call to do a disk-drive transplant. The second floor of the client's building was "the computer graveyard" where I found a PC with what I assumed was a working 3.5-inch drive.

Replacing the drive
Ideally, you'd like to turn on the donor machine and test the drive to make sure it works before you remove it. In this case, the 3.5-inch drive was pretty much the last thing still attached to the old computer, so we just crossed our fingers and hoped that it would work. Here's the process we followed:

On the donor machine:
Let's start by harvesting the drive.
  • Remove the cover.
  • Look at the large ribbon (cable) plugged into the back of the drive and note which side has a stripe of a special color. (It's usually on the left as you're facing the back of the drive.)
  • Gently remove the two ribbons plugged into the back of the drive.
  • Remove the screw or screws holding the drive on the frame. (There was only one on our donor machine.)
  • Push on the front of the drive and slide it out of its track and into your hand.
  • On older machines, you’ll have to remove the screws connecting the drive to the drive rails and set the rails aside.
  • Take the can of air and blow any dust bunnies out of this drive.

On the target machine:
At this point, let’s remove the old drive from the target machine.
  • Remove the cover.
  • Look at the large ribbon plugged into the back of the drive and note which side has a stripe of a special color.
  • Remove the drive in the same way you did on the donor machine.
  • Connect the donor drive to the target machine's drive rails, if they exist. (In some PCs, the drive simply slides into place.) There are usually two sets of holes for connecting those track slots. Hold the drive and the slots in place to determine which set of holes to use.
  • Slide the drive gently into place.
  • Connect the screw or screws holding the drive on the frame.
  • Gently connect the two ribbons by aligning the side of the ribbon with the specially colored stripe. Use the number 1 side of the pins.
  • Turn on the machine and make sure the drive works. Then power down and replace the cover.

If the light stays on, there's something wrong
What if you plug the cable in the wrong way? If there's no clear labeling on the drive or no obvious specially colored stripe on the ribbon cable, just connect the ribbons to the drive and make sure the connections are snug. Then turn on the machine.

If you've connected the large ribbon backwards, you'll know right away. The "drive busy" light on the 3.5-inch drive will light up and stay illuminated. (And you won't be able to use the drive.) Just power down, disconnect, and reconnect the cables correctly, and your client should be able to use drive A again.
If you'd like to comment on this article or share your favorite tips for troubleshooting hardware problems, please post a comment below or send me a note.

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