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Thread: DVD diode removal.

  1. #1
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    Default DVD diode removal.

    How do you get the diode out of the alloy heatsink/mount?
    Also do they all have no 'window' on the front of the diode?

    Jim

  2. #2
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    Hi Jim,

    Sorry - can't help with the removal part... My diodes came "Pre-Removed"

    As for the window - I thought there was no window until the other day when the light hit it just right - I could see a blue tint on the output hole of the diode. So, at least in the case of my diodes, there is a window....

    -Andy

  3. #3
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    I'll go to the workshop and have a closer look at them under the magnifier.

    Jim

  4. #4
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    I've had a good look and there is no lens/window.
    I have taken one out of the heatsink by using a dremmel to cut into the heatsink down each side and then split the heatsink.
    I tried it on a read diode rather than the write because I dont want to damage the diode.
    My only concern is that with the diode being open the chances of contaminating it with dust is great which I dont think would be good for the diode life.
    If I do do it this way, will it be ok to clean the diode with a compressed air duster?

    Jim

  5. #5
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    Jim
    All the diodes I have used have had a window on them I actually thought the window was part of the 5mm or 9mm can physical form...and yes very gentle blowing with air duster should be ok.
    I have - very gently heated the ally plate to let it expand and release the diode which you may need to tap very very carefully from the output end - careful not to damage the case or break the window....oops you aint got one to star with .
    I have also used the reverse of the heating process to maount the diode and ensure it is held firmly. Just dont get it too hot and let it cool prpoerly before operating.
    Incidentally the 'other' LD in there is not the read diode but actually the CD diode. One wave length diode for each disc format, they just use lower power settings for reading and writing.

    Rob

  6. #6
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    To clean a diode ideally, short the terminals with a clip to protect it and give a means to hang it from a wire so it can't be knocked off, then hang that in isopropanol, or pure methanol, or acetone. Boiling acetone is even better, is used for cleaning raw diodes after mounting, but if you do that, do it outside, it's as dangerous as a small bomb, and the actone should be heated indirectly via a pot stood in hot water, not directly, even by hot plate, because vapour can be ignited by the thermostat if it can get to it.

    The safest way is to drip pure solvent onto the diode window to wash off dust.

    Re heat, I think the diodes will take short exposures (2 minutes or so) to 100 degrees C. Not sure though, the ones I tested did, but they weren't anything special, I haven't risked a new one yet. I don't like the heat-clamp method, it might stress it over time. A close tolerance fit and some indium-based solder is better, which is when the solvent clean will become vital, probably, the flux flows where it will.

  7. #7
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    I've "harvested" several new DVD's to get diodes. At first, both diodes were 5.6 mm TO-18 style and with windows. BUT, I've found two oddballs - I can't remember the make. One had a red LD with a base only and no top hat. I handled it carefully and got it in a holder quickly to protect it. Works good as a "pointer" drawing 250 ma. The other oddball was my last one - a 16x IO Magic - had a bare junction diode for the IR. The red was normal. I destroyed the IR before I realized what was there - glue and diode.
    I use large side cutters to "nibble" the alloy housing appart for diode removal.

    Mike

  8. #8
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    Well Jim curiosity just got the better of me and I blame you
    I was gonna keep these drives in tact till I was ready to use the diodes but I just had to open one up tonight to see. Crazy thing is the insides look just like one i raped before xmas and the optical pickup is identical in layout and construction to the one in my stripdown gallery appart from the base plate heatsink-a-ma-jig is made of copper not ally and just like you said the dvd diode is wide open to the elements.

    What I am now gonna do is keep the diode in its little holder and use it this way - so avoiding getting it messed up while removing and i have removed the focus assy and theived the glass ar window that is beneath it - see my stripdown gallery for a pic. This is an almost perfect fit over the end of the diode in its holder and I will secure this in place with something - dunno what just yet - to seal it from the outside world. I may deliberately angle it a little so as to put any small back reflections off axis so they dont help to destroy the little blighter.

    Im glad I looked now as I have been machining a diode mount that will not work with this setup so its back to the back of an envelope for me.

    Rob

  9. #9
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    http://photonlexicon.com/gallery/DVD...down/barediode

    does it look like this Jim....

    Rob

  10. #10
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    Maybe the reason they are *open* is to up the power so they can write at 20x .
    It was the same in the Liteon and the Sony.

    Jim

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