S.P.KRISHNA
Active Member
Why there is a caution not to play scratched disks on the players . Will it effect the performance of the player ?
Thanks
Thanks
Scratched Disks
- Thread starter S.P.KRISHNA
- Start date
Scratches on the disk cause the laser to go crazy. In trying to read the data on a scratched disk the laser has to frantically move up and down, which is why you get those alarming sounds coming from the player when it gets "hung".
TIP: apply a small amount of Colgate toothpaste on the scratched portion. It really works.
TIP: apply a small amount of Colgate toothpaste on the scratched portion. It really works.
What does colgate toothpaste do to lasers? It will diffuse them further right? How will it work to improve laser pickup?
I much prefer Ayrurvedic toothpaste for cure - totally herbal without grounded animal bones for calcium and babool - I heard its good for red lasers. Meshwak is good for blue lasers.
Regards
:lol::lol::lol::lol::lol:
Guys..Please add some smileys to your suggestions.Otherwise some may follow them seriously....
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soulforged
Well-Known Member
soulforged
Well-Known Member
oh...and btw 
I can't explain the remedy, but it seriously works. And no, Ayurvedic toothpaste will not work because it does not contain baking soda...
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
Actually prospective double-blind randomized placebo-controlled clinical trials on mice has proven the efficacy of meswak and babool in improving the focus and tracking of blue and red lasers. 80% of mice reported improved pace, timing and rhythm in SQ with fewer than 1% reporting no improvement at all. Side-effects involve only minor rib-tickling sensation, appearance of lunacy and potential embarrassment in public ...
Take that <Paff>!
hyeah:Cheers
Hi
I think all cd players has error correction method to read lightly scratched CDs. So If CD is heavily scratched
more work has to be done by player which in long run is not good. So better take up backup copy and play clean CDs.
Actually prospective double-blind randomized placebo-controlled clinical trials on mice has proven the efficacy of meswak and babool in improving the focus and tracking of blue and red lasers. 80% of mice reported improved pace, timing and rhythm in SQ with fewer than 1% reporting no improvement at all. Side-effects involve only minor rib-tickling sensation, appearance of lunacy and potential embarrassment in public ...
Remaining 19.2 % :lol:
S.P.KRISHNA
Active Member
My question is not properly answered .Will it effect the adjustment of laser beam as I was told that there will be a shift of the optical Axis of the beam as it gets Jammed by moving forward & backward while reading a scratched disk. Is it true? If it is true then how to identify this.
Regards.
Regards.
actually prospective double-blind randomized placebo-controlled clinical trials on mice has proven the efficacy of meswak and babool in improving the focus and tracking of blue and red lasers. 80% of mice reported improved pace, timing and rhythm in sq with fewer than 1% reporting no improvement at all. Side-effects involve only minor rib-tickling sensation, appearance of lunacy and potential embarrassment in public ...
Take that <paff>!
Cheers
ignorance is bliss
CHEERS
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actually prospective double-blind randomized placebo-controlled clinical trials on idiots has proven the efficacy of meswak and babool in improving the focus and tracking of dingbats. 80% of dumbasses reported improved pace, timing and rhythm in sq with fewer than 1% reporting no improvement at all. Side-effects involve only rib-tickling sensation, appearance of lunacy and potential embarrassment in public ...
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Yes there will be a shift of the optical axis of the beam. You can identify this from the alarming noises that come from the player during playback of the scratched portion. It will be bad in the long run.
madbullram
Well-Known Member
gobble/shredder: I think lets leave personal remarks and focus on the topic. Thanks
http://www.wikihow.com/Fix-a-Scratched-CD
http://www.wikihow.com/Fix-a-Scratched-CD
Look at the image above. The objective lens of a CD pickup has a numerical aperture (NA) of 0.45; thus the outermost rays will be inclined at approximately 27 degrees to the normal. Refraction at the air/disk interface changes this to approximately 17 degrees within the disk. Thus light focused to a spot on the information layer has entered the disk through a 0.7mm diameter circle, giving good resistance to surface contamination.
A fundamental goal of consumer optical disks is that no special working environment or handling skill is required. The bandwidth needed by PCM audio is such that high-density recording is mandatory if reasonable playing time is to be obtained in CD. High-density recording implies short wavelengths. Using a laser focused on the disk from a distance allows short-wavelength recordings to be played back without physical contact, whereas conventional magnetic recording requires intimate contact and implies a wear
The information layer of CD is read through the thickness of the disk. The figure above shows that this approach causes the readout beam to enter and leave the disk surface through the largest possible area. The actual dimensions involved are shown in the figure. Despite the minute spot size of about 1.2micro millimeter diameter, light enters and leaves through a 0.7 mm-diameter circle. As a result, surface debris has to be three orders of magnitude larger than the readout spot before the beam is obscured.
The size of the entry circle is a function of the refractive index of the disk material, the numerical aperture of the objective lens and the thickness of the disk. CDs have no protection, but fortunately the method of readout through the disk thickness tolerates surface scratches very well. In extreme cases of damage, a scratch can often successfully be removed with metal polish. By way of contrast, the label side is actually more vulnerable than the readout side, since the lacquer coating is only 30micro mm thick. For this reason, writing on the label side of CD is not recommended. Pressure from a pen could distort the information layer, and solvents from marker pens have been known to penetrate the lacquer and cause corruption. The common party-piece of writing on the readout surface of CD with a felt pen to show off the error correction system is quite harmless, since the disk base material is impervious to most solvents.
That was the good side. Now let us understand the bad side.
Remember that the CD is a mechanical device. The 'land' and 'pit' are physical variants just below the surface that reflect the light in different intensities. The amount of recflected light determines the ones and zeros. Given the minute amount of differences we are talking about, the error correction mechanism has a tough job to do.
Most laser assemblies are allowed to pivot in order to keep the laser beam in contact with the spiral data track. The high speed of rotation and the movement of the laser head can cause resonances that shift the laser head. When this happens, the data read will be incorrect leading to jitters and errors. A laser's direct hit on a 'pit' will most likely allow the laser to read the pit correctly. While error correction can extrapolate and fill in the missing data, better tracking will mean lesser errors leading to lesser error correction and better sound.
Sources and Acknowledgements
1. Stereophile
2. The Art Of Digital Audio by John Watkinson
Cheers
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Thanks for posting the link. I think it will bear out what I have been saying all along.
Regards
Sure. This toothpaste solution (er no paste !) has been discussed before as well http://www.hifivision.com/articles-guides/4812-fevicol-vinyl-cleaner-2.html#post55792
Cheers
You have to remember two things. The data in a CD (or Lands and Pits) are nearer the label side. This has been done for protection as the other side is more susceptible to wear and tear. The label to a large extent protects the side that is nearer the data.
Toothpaste is a abrasive material. When you rub this on the CD, you are actually removing a very tiny area of the surface, and thus leveling the surface. You are not removing the scratch. You are reducing the level of the surface to the depth of the scratch. When you are doing this, unless you use extremely fine material for grinding, you are going to leave innumerable new scratches on the surface. This could actually worsen the situation rather than help it. But, given the fact that the laser beam has a high margin for error, this technique will work for most extremely minor scratches.
The best method is to keep the CD/DVD protected, and handle it properly. I would never use a CD Pouch, as every time you insert and remove the CD you are scratching both sides. A CD/DVD jewel case is always the best.
Cheers
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