salvaging a cd drive - what can i expect?

Forum 2005-2010 (read only) General Frequently-Asked Questions
1

I have a old cd drive which i'm looking to open up. What are the things i can expect? A BLDC motor? A ESC? some kind of leds?

2

open it up, you might find a stepper motor, a spindle motor, led(s), cool looking boards that I (to be honest) have no idea what they do. you may have some nice headers as well. But to be honest there aren't that many reusable parts (well, for electronics anyway. they make cool art materials). just take your screwdriver and go.

3

You'll typically find some gears and such (mainly for the cd tray opener), maybe a micro-switch or an optical interruptor (to tell when the tray is open/closed). There will be some form of short linear slide mechanisms (for the laser to ride on); the laser itself (provided you can figure out how to power it); the focus mechanism for the laser (generally a part of the whole laser system - it may be almost impossible to separate the two without damaging one or both). Depending on the drive and your need, the flat sheet metal that forms the outer case of the drive could be handy for things like custom brackets and such (if you have some common hand tools like nibblers, sheet metal snips, etc).

4

CD drives are one of my favorite things to take apart. They trick me into thinking I might actually do something with the internals. Here are some of the usual findings:

  1. Spindle motor. Most modern computer CD drives will have some sort of brushless three-phase motor. These are tough to do anything with on their own, but can potentially be useful. Usually there are hall-effect sensors used by the driver chip for speed sensing as well. (rather attached to the motor.) Audio CD players may have a DC motor here.

  2. Head motor. Some of these are bipolar stepper motors, and some are DC motors. Usually there's a fancy lead-screw and some small gears. Typically if you have a stepper motor, it has the lead-screw attached directly, and it will be mounted in an inconvenient bracket that provides important mechanical properties (a bearing at the far end of the lead screw) that makes it difficult to take apart.

  3. Tray motor. Usually a nice DC motor with some good gears.

  4. Head:
    A) For fine positioning of the head, there are "voice coil" actuators in there that will yield a couple of small rare-earth magnets.
    B) Somewhere in there is a laser diode. CD-RW or DVD-RW type drives may contain more than one laser (separate lasers for reading and writing, I think.)

  5. Usually there's some sort of rare-earth disk magnet on the bits that hold the CD to the spindle. Often in the mechanical parts of the drive rather than the head itself.

  6. The electronics tends to be a bit unusable :frowning: Most of the functions of the drive are implemented in a single monster chip, so you usually can't find separate motor driver chips, and when you do they tend to be complex beasts with hard-to-find datasheets. There are usually some nice low-profile caps and some interesting limit switches, but they'll have really short leads by the time you get them off.

  7. there's probably a 0.1inch jumper on the IDE Master/slave selection. Those are annoying to have to buy; keep a collection...

5

Depending on your model, you may also be able to get the headphone jack (2.1mm) and you may be able to salvage a few larger non-surface mounted components (if your model is older).

6

Here's a photo of the parts that I salvaged from a CD-ROM drive a few years ago:

Imgur

7

oh yea those silicone washers, those are handy if you have a thin computer case and a cheap fan causing noise

8

To add to this thread - how to reuse some of the salvaged parts:

How to use the stepper that drives the head:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1255806765/0

How to use the brushless spindle motor (BLDC) as a rotary encoder (pretty useful for user interface):
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1219763383/18

9

Thanks everyone. Managed to salvage and use the motors excepting the bldc motor. My idea was to use this to teach students to program a basic cd drive functionality. I think this will help students relate better as they see and use a cd drive everyday.

Now onto getting the bldc motor working!!!

10

If it has a 16x dvdr or higher the laser diode is useful to make it burn objects ;). But you'd need a laser driver and a housing to house the diode with a lens to focus the beam to pinpoint :)... Well it's what i did from a blue Ray drive anyhow...

11

Hi pracas,

A while ago, I did some experiments with the BLDC from a CDROM. Most of the BLDCs are just bi-polar servos. Take a look at my post here (http://www.kerrywong.com/2010/03/22/a-simple-dual-h-bridge/) and if you scroll down you'll see the motor, which is from my old Plextor CDRW.