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  1. Many DVD recorders start to have "drive problems" after lots of use. I have noticed that it's usually NOT a motor issue, but instead a simple problem with "recognizing" discs. Many times the problem is resolved by simply cleaning the lense. But, when it isn't a "dirty lense", it's usually a laser alignment, focus, or laser diode issue.

    I'm not the most technical individual, but it would seem to me that there should be some way for the average user to re-adjust the laser/lense focus/alignment.

    I have searched the internet and have only found a handful of info. Here's two links to threads that seem to examine this issue somewhat.

    http://forum.rpc1.org/viewtopic.php?t=10055

    http://club.cdfreaks.com/showthread.php?t=208298

    It's frustrating when a DVD recorder starts having problems formatting or recognizing discs. If there was an easy way to re-align the laser/focus, that would be a quick fix for many of us. Has anyone ever looked into this issue?

    Any advice on actually REPAIRING a drive that starts having problems recognizing discs?

    D'oh!
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  2. Mod Neophyte Super Moderator redwudz's Avatar
    Join Date: Sep 2002
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    If all else fails, including a laser lens cleaning, you probably have little to lose. The problem seems to be that's it apparently just guesswork for making the adjustments.

    Another problem to check while you have the unit open is that the laser assembly can freely slide on the guides.

    You might take a look here for some background on laser focusing. It's for a CD drive, but a DVD is similar, just tighter tolerances. http://www.howstuffworks.com/cd5.htm

    Or this PDF: http://www.electronicsforu.com/EFYLinux/efyhome/cover/cdplayer.pdf

    Or this PDF (About 8Mb , but lots of detail): http://www.optics.arizona.edu/ODSCsponsors/03-01-31-417-Semi-AnnualReport/D%20-%20Mansuripur.pdf
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  3. Member hech54's Avatar
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    Location: Yank in Europe
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    (What amazes me) is how incredibly tiny the data track is -- just 740 nanometers separate one track from the next (a nanometer is a billionth of a meter). And the elongated bumps that make up the track are each 320 nanometers wide, a minimum of 400 nanometers long and 120 nanometers high.
    http://electronics.howstuffworks.com/dvd2.htm
    What amazes me more is how anybody can possible think they can calibrate or "repair" something that works under such incredibly minute tolerances with the tools they have lying around the house.
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  4. Originally Posted by hech54
    (What amazes me) is how incredibly tiny the data track is -- just 740 nanometers separate one track from the next (a nanometer is a billionth of a meter). And the elongated bumps that make up the track are each 320 nanometers wide, a minimum of 400 nanometers long and 120 nanometers high.
    http://electronics.howstuffworks.com/dvd2.htm
    What amazes me more is how anybody can possible think they can calibrate or "repair" something that works under such incredibly minute tolerances with the tools they have lying around the house.
    True, however... as the previous reply mentioned; what have you got to lose by trying? The drive is already out of alignment. If all else fails, why not?

    D'oh!
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  5. Originally Posted by redwudz
    If all else fails, including a laser lens cleaning, you probably have little to lose. The problem seems to be that's it apparently just guesswork for making the adjustments.

    Another problem to check while you have the unit open is that the laser assembly can freely slide on the guides.

    You might take a look here for some background on laser focusing. It's for a CD drive, but a DVD is similar, just tighter tolerances. http://www.howstuffworks.com/cd5.htm

    Or this PDF: http://www.electronicsforu.com/EFYLinux/efyhome/cover/cdplayer.pdf

    Or this PDF (About 8Mb , but lots of detail): http://www.optics.arizona.edu/ODSCsponsors/03-01-31-417-Semi-AnnualReport/D%20-%20Mansuripur.pdf
    Thanks for the info... I'll start reading

    D'oh!
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  6. I'm wondering what is the primary CAUSE of misalignment issues in a DVD recorder? We have all had drives that simply STOP recognizing discs. I realize that it could be something serious like a dead laser diode, BUT if the drive recognizes CD's and not DVD's, or SOME DVD's, etc.... it's probably some kind of alignment issue. Could it be the tracking motor? The people in the forum threads that I initially posted seem to have found a way to make some adjustments... but the document mentioned in one of the threads is no longer available.

    What we need is a tech-head to give an example of what screws to turn in order to adjust the tracking, focus, etc. At least where to look for such adjustments in a drive.

    Anyone in THIS forum ever tried to make these adjustments?

    D'oh!
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  7. Member hech54's Avatar
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    Originally Posted by D'oh!
    True, however... as the previous reply mentioned; what have you got to lose by trying?
    I must have missed that in the first two posts prior to my first post.
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  8. Member
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    Until and unless somebody figures out how to do it, it's probably much easier to just replace the burner as many have done for some LiteOn recorders especially considering burners are only $30 plus or minus a few bucks.
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  9. Member
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    The laser assembly is able to move up and down for focus that way and since it is a contiuous screw drive that moves the heads back and forth I would not expect that there is a alignment needed for that.

    The ones I have seen seem to be a laser going bad or a mechanical problem.

    I Speak from watching Personal portable DVD players as a part of the repair operation. I do not suspect that the computer drives are less capable.

    IOWs if I hit the switch that tells the unit the door is closed I can see the laser flash and move up & down as well back and forth. Many of the models will only spin if the laser flashes and reads that a disk is there. I have also seen either the CD or the DVD playback go out without affecting the other. I don't see how that could be an alignment issue.

    BTW FWIW when these drives are shipped they solder three leads together that protects the laser. 1 for CD and 1 for DVD and 3rd is common. The drives have no real electronics the controllers are on the mainboard and the drive will have leads for head positioning motor, disc spinning motor and another for the laser assembly.
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  10. Until and unless somebody figures out how to do it, it's probably much easier to just replace the burner as many have done for some LiteOn recorders

    Yeah, but do all recorders use standard IDE drives? I think not.
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  11. Member
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    See http://club.cdfreaks.com/showthread.php?t=139688&page=2&pp=25
    post #45 to find someone fixed a recorder by replacing laser parts. The problem would be finding a parts source.
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  12. Member
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    Check post #1259 at http://club.cdfreaks.com/showthread.php?t=103379&page=51#post1789836
    to find parts source for any interested.
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  13. Member
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    There are two levels of alignment for the laser assembly. The first level is the mechanical alignment. But that is just where the alignment begins. The tone of the questions and comments make it appear that many think that is all there is to it. But there is another part of the alignment process that hasn't been mentioned. The alignment AND focus of the laser assembly is servo controlled. The servo control circuits in the player uses the signal from the laser to determine the precise track position. The servo circuits apply positioning control input to small coils in the laser assembly which moves the laser assembly as required to precisely align the laser with the track. There is a lot more to "aligning" the laser than grabbing a screwdriver and a hammer and "aligning that sucker".
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  14. Member
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    We have an older version of a Playstation 2 that plays games written on DVD media but doesn't always play games written on CDs. I looked into the problem and found that the older PS2s did this but the newer ones are OK. When I looked into it more, I found that there's a mechanical adjustment for the laser focus (the laser head height). I was able to make this adjustment and get either CDs or DVDs to play, but not both at the same adjustment. To answers the question asked by D'oh!, I've read that the reason DVD/CD players get "out of alignment" is that over time the laser becomes weaker which changes the focus. There is no way you can adjust the track that is 320nm wide but the focus can be adjusted. A laser does have some convergence/divergence so it makes sense that a screw is sensitive enough to focus it.
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  15. I've adjusted CD players and drives before (not tried a DVD). Sometimes it works, sometimes not. They don't last forever. I think 6 months was the longest after adjustment, but it's better than nothing.
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