Combo drives and optical focus

[coius]

I just got a new laptop, and the optical drive will read at first (mount the disc) but it will not read past that. Ditto on DVDs, it will mount and read the menus, but will not go past that (can't play movies).

I am told the laser is out of focus. The system has been reinstalled, and it won't even run a disc installer if I try to boot from the disc. it hangs the machine. Another optical drive (CD-ROM) works fine. so the slot is fine.

Anyone know how to adjust the laser in these? How far do I need to turn the screw?

 

[tomlee59]

On optical drives, there's rarely an electrical adjustment for focus. The symptoms you are describing could indeed be a focus problem, but electrical ones are rare. Much more common is a bent mechanism. The optical assembly moves radially along a track that has to stay fairly parallel to the disc surface. If the frame and track are bent relative to one another, the focus will change from the inner to outer tracks. Your drive's behavior is consistent with the focus being good on the inner tracks, but not so good further out. Since the optical assembly is anchored solidly near the spindle, that's exactly the behavior you'd expect from a bent frame. Open up the drive and look at it carefully as you slide the optical assembly along its full travel. I'm willing to bet that you'll notice something is bent. If not, post back.

 

[wally]

...Open up the drive and look at it carefully...

And while you have it open, also look very carefully at the hub shoulder surfaces that try to assure that the disk rotates in a plane with minimal wobble. If there is too much lint, or worse one grain of grit caught on the flat circular friction ring clamping zone, the disk will have an up and down wobble that is small near the center, but increases as the head tries to track and read data farther outwards.

 

[coius]

Good news: I found the screw for focus and started playing with it. Before long, i was able to transfer SOME files off the drives.

Bad News: I broke the screw to the focus. Although I was dead on about the focus screw, it's a moot point right now. My dad has an optical Combo drive that only the CD-RW works. I heard that DVD-Rs are more picky to pick up. Since the dye makes it harder to read, I will be using one to calibrate the other combo drive. I will let you know how it goes!

 

[tomlee59]

How do you know it's for focus? The screws that one can normally adjust are for laser power. Adjusting power can partially hide some focus problems, but it won't fundamentally solve the problem of a misaligned track/bent frame.

If the screw was on the sliding optical assembly itself, I doubt very much it was for focus. Again, if it were a focus problem, it would cause trouble everywhere, not selectively. It sounded from your description that you were getting reliable reads on the inner tracks, so that makes me doubt that you had a focus problem.

As for DVD vs CD, older drives had just one laser for both (a red one). That created problems with reading writeable media (except CDRW, interestingly enough). Newer drives have two lasers -- one red, one IR -- to handle all media types without trouble.

 

[coius]

I went ahead and bought a combo drive off of ebay for $17.99.

It's from a sony unit, but these days, it's pretty much moot. Since most optical drives have the same ATAPI connector at the back

 

[tomlee59]

I went ahead and bought a combo drive off of ebay for $17.99.

This method is an excellent way to solve a focus problem!

I hope that the drive works well for you!