such thing as disc data disappearing? how long do DVDs last?

dcassidy · Member Joined: 16 Jul 2004 Location: Munich

OK...I think I got it....

I decided it must be the ability of the laser to pick up and recognise the data...so I popped a CD cleaning disk into to Sony...ran it a few times.

I can now see all the disks.....I guess there must have been enough grime on the laser to stop me reading DVD+RW and DVD+R but OK not enough to stop it reading commercial disks.

Is replacing the laser (assuming it is grimy) a DIY job or best left to the professionals. ??

Thanks for the direction and help BJ_M ...I feel a right prat now...

Cheers,

Dezzz.
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gmatov · **Banned** Joined: 21 Nov 2002 Location: Pgh Area

OK, here's a ? for you.

You run NERO CD Speed, or DVDInfoPro or any other check program, and it says "All's well", just what does that mean?

That a 0 is here and a 1 is there?

What is there to say the disk is an exact copy of the file burnt from? Where is the "Compare" function?

I don't see anywhere that DVDInfoPro searches your HDD to find the file you just burnt from, particularly if you do a check the next day, after a shut down/reboot..

It may see a "reflect", "refract", or a "nothing", so bad bit, so bad burn, but if the "reflect" or "refract" is not a 0 or 1, whichever it should be, right there, but if it does not know what belongs in that area, how can you say it is a good burn/bad burn.

GIGO. It reads bad data, but it IS reflect, refract, not a nothing, so good burn.

Does this make sense?

Cheers,

George

BJ_M · Patron Joined: 30 Jul 2002 Location: Canada

BJ_M · Patron Joined: 30 Jul 2002 Location: Canada

ussually not worth replacing anyway -- as other parts will be or are worn also ...
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nerys · Member Joined: 31 Mar 2003 Location: Levittown PA

"There is no "silver coating" on a DVD-R. The foil and dye is sandwiched between a plastic upper and plastic lower. What you claim happened is physically impossible. "

Like hell

I hav SEVERAL where the silver layer is RIGHT underneath the labeling and I HAVE PEELED them

that is why I test all media with a screw driver I put a nice gouge into the top of the disc. if I see nothing on the other side I buy lots of it

Chris Taylor
http://www.zodiacreview.com/

lordsmurf · Posted: Feb 01, 2005 01:21

Believe what you want, but the facts are not on your side. There IS a plastic upper layer. A screw driver probably went through both layers. There is no "label" on the media, maybe a silkscreen or other thermal/inkjet layer on the plastic.
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Skith · Member Joined: 17 Oct 2004 Location: Bottom of the ocean

Straight from the horses mouth:

http://www.dvdrw.com/information/white-papers.htm

Look at the PDF "DVD+R - A Write Once System for video and data applications" on the above site, you will see this diagram:

Some links to the DVD-R Forum:

http://www.dvdforum.org/forum.shtml

http://www.dvdforum.org/gen-discbond.htm

nerys · Member Joined: 31 Mar 2003 Location: Levittown PA

sorry man does not matter. the physical disc I can hold in my hands trumps any diagrahm

if that is dvd spec this just means whoever made this disc did not follow spec cause I am sorry you can not "slice" through polycarb that easy and you can not "peel" polycarb as if its mylar. I might still have it I will try to find it. I THINK (not sure) it was some old comp usa brand 1x/2x discs.I removed the silkscreen or whatever it is AND a super thin film like shiny metallic silver layer. when I got it all off (came on in peices not one peices too thin to get it all at once I tried

I was left with a CLEAR poly disc (like the dummies you find in soindles) and a rainbowy color effect (assuming thats the dye

yes by label I meant whatever it was that they use to put there logo on top of the disc

I have also had discs with DISTINCT layers of polycarb that I was able to split and seperate into 2 halves

I stay away from them too

ie if I can visibly "see" the line between the 2 poly layers I stay away.

Chris Taylor
http://www.zodiacreview.com/

BJ_M · Patron Joined: 30 Jul 2002 Location: Canada

i actually saw a couple of these weird disks also -- they had no top polycarb layer .. and were real flexible .. this was a few years back and never saw them again ..

i found out when i tried to pull off a printed label on one I recall, becuase the customeer put it on crooked and the disk would not play right .. and i killed it ..
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Zisguy1 · Member Joined: 04 Jan 2005

Skith · Member Joined: 17 Oct 2004 Location: Bottom of the ocean

joeg04 · Member Joined: 23 Dec 2004

Simple experiment to predict "data disappearing" for a certain DVD-R disk:

I just made an experiment, that is easy to replicate. You just need a ruler, a hair dryer, and less then 1 minute of time.

1) Take a DVD-R, that is suspicious for future "data disappearing", for example Princo.
2) Check the top side with a ruler, whether it's flat.
3) Heat up the bottom side of the disk. Use a hair dryer (about 1800 W) for 10 to 15 seconds, from a distance of 1 inch.
4) Check again the top side with a ruler, whether it's still flat or significantly warped.
5) If the disk is flat before AND after heating up, then "data disappearing" will not happen, else it can happen.

The heating simulates the higher temperature in a DVD player.

I carried out this experiment with several disks.

The following disks were flat before, but warped by 1mm immediately after heating up:
- Princo (white top, not printable),
- LONGTEN001 (white top, printable)*,
- A disk with paper label applied*.

The following disks were flat before and after heating up:
- RiData (white top printable),
- Philips (silver-top).

* Those disks are no longer playable on the outer side in a Pioneer DV-454, but were completely playable shortly after burning, 1 year ago. The others have no playability problem. I think the Princo may have problems in other players (There are many reports about bad Princo disks).

The three disks, that showed warping after heating up, have all one thing in common: They have an extra white layer on top, that might expand/shrink differently with temperature changes than the rest of the disk, and thereby warping the disk.

Experience shows, that "data disappearing" is a PROVEN FACT.
I agree with Lordsmurf, that the problem is not the DYE. I conclude from the experiment, that the problem is WARPING. The disk is either already warped (production error) or warps itself, caused by temperature changes and under influence of humidity. Warping may lead to focussing problems in the laser optics.

lordsmurf · Posted: Apr 16, 2005 15:54

I would still not lump that into a "data disappearing" category, but that is indeed an excellent addition to this post. Most time, warping is a cause of improper storage. Discs that are warped or imbalanced refuse to burn to begin with.

Having a DVD player that heats up bad, and discs that are made from comparatively more flimsy platters, is subject to death. Much like scratches. Although I will have to say that a hair dryer is SIGNIFICANTLY more heat than a typical electronics component. For these same reasons, never leaves discs in the sun, in the car, etc. Dye can be altered at a certain degrees, but I don't remember when that is. It's hot. Oven hot.
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joeg04 · Member Joined: 23 Dec 2004

rgs_uk · Member Joined: 30 Apr 2004

Marvingj · Posted: Apr 16, 2005 19:39

Heat can kill disc. Especially the Sun......

joeg04 · Member Joined: 23 Dec 2004

I think the heat in the experiment, I described above, will not kill the disk, because I limited the heating up to 10 - 15 seconds only. So the disk gets warm, but not really very hot.

With this experiment I observe a difference between good and bad media. With the high temperature I wanted to warp the disk so much (1mm), that I can easily see the warping with help of a ruler. I think fosussing problems may already occur with much lesser warping.

lordsmurf · Posted: Apr 17, 2005 02:41

A blow dryer gets SUPER HOT in a matter of seconds. In fact, you can often burn skin or scorch hair. Hair dryers are really bad to use. Even for hair.
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joeg04 · Member Joined: 23 Dec 2004

Try it out yourself with a hair dryer and a DVD-R. If you touch the DVD-R immediately after that 10 to 15 seconds, you will observe that it is warm but not super hot.
While heating up I move the dryer slowly a little bit, so that not all heat is concentrated only on one point of the disk. The whole bottom area of the disk should heat up uniformly.

joeg04 · Member Joined: 23 Dec 2004

In ISOBuster 1.7 version history I found the following new feature:

joeg04 · Member Joined: 23 Dec 2004

lordsmurf · Posted: Apr 18, 2005 20:02

The "cooling down" you refer to in ISOBuster is being taken out of context. Not the same thing.

If you want to measure temperatures, then do a thorough test. Measure the heat of the disc, as played in 2-3 separate players, going in intervals of 1-6 hours, at each hour.

I still think the hair dryer is too much, too fast, and too hot. It's skewing the results. You also have to insure your measurement device (a ruler) is perfectly flat, as any bending in it will skew the other plane too. You'll likely need to rig up a safe measurement stand, not just "wing it" by handholding.

I'd like to see this test, but I think at this point in time you're hastily jumping to conclusions. Nobody is in a rush here, so take some time to do a thorough test. It will take some time to do.

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joeg04 · Member Joined: 23 Dec 2004

joeg04 · Member Joined: 23 Dec 2004

I opened my Pioneer DV-454 for further investigation. I could not measure the temperatures in the DVD drive because I don't have an adequate thermometer. If I touch parts in the drive, they seem to be not very hot, including the top side of the disk. Perhaps only a few degrees above room temperature, if the chassis is open. What I still don't know is, how much warping of the disk is required to cause playback problems.

I saw another interesting effect: At the silver-top Philips DVD-R, the laser beam was shining bright through the disk (see photo below).
Could it be, that a white top labelling layer would reflect the laser beam strong enough to cause interference with playback?

Caution: I advise others not to repeat this experiment, to avoid exposure to a laser beam.

lordsmurf · Posted: Apr 20, 2005 13:39

Well, then maybe somebody else will read all this and have the time for such a thorough test. Until then, zero conclusions can be drawn. Far too premature. You've provided a good hypothesis, but it needs lots of testing to confirm or deny. My feeling is that it'll be totally denied, but the test need be done by somebody someday.
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joeg04 · Member Joined: 23 Dec 2004

lordsmurf · Posted: Apr 20, 2005 15:22

ana_costa_brazil · Posted: May 03, 2005 04:24

lordsmurf · Posted: May 03, 2005 06:13

CD-R is different. The discs were not tested after they were burned. They are crap media. And the details on "every software" to fix them are a bit sketchy. Definitely not an "open and closed" case, far too many unknowns and not a thorough examination from burner to supposed time of death.
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macrovision · Enemy Joined: 08 Mar 2005 Location: Hostile Territory

I wanna add my 2 cents being a tech.....Dye based media is simular to polaroid camera film with the exception that it "burns" using frequency instead of oxygen. Theoretically if you expose a fresh unburned disc to the proper frequency using a laser you will burn it even if your not transfering data(kinda like carrier wave frequency) so my guess is if you store disc next to the T.V. you may compromise its reliability simply because televisions emit high frequencies from the flyback(step-up transformer) and other electronic equipment emit high frequencies as well (like storing cassette tapes near your speakers...even if they're magnetically shielded you risk data loss...My 2 cents!
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Is what we learn indeed a fact, or someones opinon?