How a laser in a Wii works.

Discussion in 'Wii - Hacking' started by jonas7611, Apr 19, 2008.

Apr 19, 2008

How a laser in a Wii works. by jonas7611 at 11:23 PM (3,523 Views / 0 Likes) 16 replies

  1. jonas7611
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    Newcomer jonas7611 Member

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    Hopefully this will answer any questions regarding "laser life":

    1. The wii laser, like any other drive laser, consists of a laser diode emitting a very shot wavelength light invisible to the eye.
    That light passes through a one way mirror prism then through a focus lense and then hits the disc.
    The disc then "mirrors" the light back through the focus lense and and gets diverted by the mirror prism to be detected
    by a light sensitive photo diode or photo transistor.

    2. The focus lense consists of a lense:) wich is mounted on a copperwire coil wich in itself is mounted around or very near
    a metal bracket.
    If the light beam is out of focus(the wii cant read the disc) the drive will adjust the current flowing through the copper coil
    either raising or lowering the lense, ergo; changing the light beams focus.

    3. The "clicking" noise in the drive can be two things:
    The focus coil hitting the lowest point on the bracket, not dangerous in any way.
    Or it could be drive sled making a stop and turning the other way very quickly, or many short stops after.
    It is not the "laser assembly", like someone stated, since it is stationary, the only thing moving in the "laser assembly" is the focus lense.


    In short: Lasers do not take any damage what so ever from different kind of media.
    If youve got any questions post here or PM me.

    //jontte, electrical engineer and electronics technician..
     
  2. Hooya

    Member Hooya GBAtemp Advanced Maniac

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    What if the laser can't focus even when it hits it's max focus out or focus in level? Does that just result in a DRE? What if you're consistently making the laser focus more in and out a lot? Wouldn't that potentially, over time, wear out the mechanism that causes the laser to focus, with an end result of the laser reading fewer and fewer sections of disks (since it can't keep refocusing) and eventually not be good enough to use consistently?
     
  3. drock360

    Member drock360 GBAtemp Fan

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    Wait, so all those clicks don't damage the wii laser at all. Wouldn't that mean that the laser is working too hard because it wasn't designed for burned DVDs?
     
  4. jonas7611
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    Newcomer jonas7611 Member

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    The disc (DVD or CD or whatever disc) is positioned roughly so close to the focus lense focal middle point, so if it can´t focus correctly it will just try again, the disc speed, media quality and dirt(on the lense or disc) will affect this.

    The mechanism is a coil of thin copper wire(and the lense itself) suspended on thin, very durable metal wires that will NOT break unless you pull on the focus lense. The coil is moved up(closer to the disc) or down(further from the disc) by the applying of a current thorugh the copper wire, the only thing that could break the coil is over current but it is limited by a circuit that will stop any current over a pre defined value.

    The laserdiode will over time( probably near 8000hrs), if you play 4hrs a day that is 2000 days of playing,) be matted and distribute a weaker beam, the photo diode will then get a weaker beam on itself and tell the drive circuit to up the current to the laser diode a little, the laser will then emmit a brighter beam for a time, then it will get a little more matted and require som more current to provide a bright beam, in time that will result in the death of the laser diode, at some point the laser diode will kill it self, If the laser diode gets more current the warmer it will get, the warmer it will get the more current will flow througt it and when it reaches a certain point the diode will fail (either a protect circuit will cut the power to the diode to prevent any damage to other electronics, or the diode will break).
    Happy to see someone reading this

    //jonas7611
     
  5. jonas7611
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    Newcomer jonas7611 Member

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    The clicking is the focal assembly of the wii dvd reader, and will not damage the laser, read my reply to hooya for some explaining.
    The clicking is the focal assembly trying to find focus in the laser beam returned from the disc and the beam sent by the laser diode if it can´t find it it will expand the focus area and sometimes it will reach the end point and the lense assembly will touch an endpoint(the click).
    Post if you want more explaining or have other questions.
    Thanx for reply

    //jonas7611
     
  6. Hit

    Member Hit GBAtemp Advanced Fan

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    How do you explain that my PS2 had problem with burned disc(didn't read them anymore, well sometimes but crashes in game) and no problems with original

    Well I'm not worried as soon Wii supports USB Host and we can connect a Portable HDD and use it to boot Iso's I'm going to get a portable Hdd and it won't even use the Laser
     
  7. Bob Loblaw

    Member Bob Loblaw Read the Bob Loblaw Law Blog!

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    Exactly. It's common knowledge that media quality affects the laser. The OP is very misinforming. Google: reflection rates

    The issue is Reflection Rates. To summarize, a brand new original retail PS2 game of the DVD variety is not burnt, they're "pressed". These carry the highest Reflection Rate, often just posted at 100%. Everything else compares against it. Now then, the single best quality DVD-R media available today will give you roughly 60% of the reflection rate of that original we talked about. 60%, that's all. And you know where I'm going with this... it goes steadily downhill from there. Crappy media hovers in the 40-50% range, while CD-R's can be even lower.
    So, as the laser fades, guess what the first things are that won't read? Backed-up copies.

    Lower reflection rates = longer read times/more retries to read disc = laser used more.
     
  8. Arakon

    Member Arakon GBAtemp Fan

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    the issue isn't just longer load times, but the laser also receives more power in order to attempt to increase readability. the more power it gets, the faster the laser diode burns out. so bad media WILL actually damage the laser, albeit only very gradually.
     
  9. jonas7611
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    Newcomer jonas7611 Member

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    The photo diode/transistor in a typical DVD reader/player will get sufficient information at between 55-75% reflection of the beam sent at the disc(it will only have to tell the fifference between a brighter beam and a darker beam)
    DVD+r has a lower reflection than DVD-r, hence the wii reading the latter one better.
    The wear of the laser diode will occur what ever media you play, due to matting of the diode over time.

    Most driver assembly failures are not the laser diode or the focus lens assembly, it is far more common that the guides that the whole assembly rides on the rails, to travel across the disc space, gets grinded down so the laser/focus assembly gets a little tilted;the beam gets tilted to so the reflected beam is shot back at a wider angle and misses the photo transistor/diode (disc read errors) then it tries again and the assembly is tilted back by the change of movement and the reflected beam hits the recieving part.

    This is very common and probably the fault I´ve repaired mostly on PS2:s, other failiures that are somewhat common is the BIAS pot losing its value a little, thus changing the BIAS current up or down, effecting the reading of discs.
     
  10. Bob Loblaw

    Member Bob Loblaw Read the Bob Loblaw Law Blog!

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    On dual layer the reflection rate goes even lower

     
  11. jamhu23

    Newcomer jamhu23 Newbie

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    The laser in a wii works like all lasers the diode cannot not magically increase it's own power it is set. The absolute most damage you could cause by using recordable media is longer seek times, which will reduce the "lifespan" of your drive UNIT not an individual part. Heres an interesting fact a heavily scratched DVD will decrease the lifespan of your drive unit more than usiing high quality Recordable Media. In short your Wii should last many years regardless of what media you throw into the drive. Remeber Wii's are noisy because they are set up to burst read.
     
  12. bennydigital

    Member bennydigital GBAtemp Regular

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    wishful thinking
     
  13. jamhu23

    Newcomer jamhu23 Newbie

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    The wii already supports usb hosts (the keyboard in linux), but they are slow. By the way if you want to boot ISOs you are a pirate.
     
  14. Bob Loblaw

    Member Bob Loblaw Read the Bob Loblaw Law Blog!

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    Welcome to GBATemp.
     
  15. Social0

    Member Social0 GBAtemp Advanced Fan

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    hold on, you aren't? [​IMG]
     
  16. Lumstar

    Member Lumstar Princess

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    Although unofficially capable... The drive isn't "supposed" to read CD or DVD discs. As you know, legit retail Wii and GC games are not actual CDs or DVDs. They use custom DVD-like formats*.

    *The original Xbox did too. But that system was meant to read CDs and DVDs.

    I don't think we've gotten Wii homebrew to read from a disc yet. [​IMG]
     
  17. jonas7611
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    Newcomer jonas7611 Member

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    The diode will not "magically" increase the power running throught it, after time the diode gets matted and therefore gets warmer, and the warmer it gets the more current will flow through it, like if you warm a NPN transistor with a cigarette lighter the heat will let more current through and when you remove the lighter the current running through the trans. will cause more heat, more heat will cause more current and so on..
    This takes more time though in a lasser diode.
    //jonas7611
     

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