You just need to get yourself a DVD Rewinder.
Of course, some people are handy and prefer to make their own, so there’s an Instructable here.
Also, the top/label side of the CD is the side you can damage by scratching. So when you take it out of the player and set it down, you should set it down label side up.
The data is in fact on the top surface of the plastic, just underneath the label. It gets more complicated for DVDs and Blu-Ray.
That’s what I thought, but your link seems to contradict this: see the “Diagram of CD layers” about halfway down the page.
The Wikipedia link provided by Bert Nobbins is correct. The CD layer diagram is shown correctly and is just underneath the print.
What do you think is not correct?
It looks to me like, in the diagram, layer A is the label on the top of the disc, and layer D, that has the data, is on the bottom of the disc, farthest away from the label.
Right, the diagram shows the top surface is the label, under that is a layer of protective lacquer, under that is a reflective surface, and finally under that is the encoded polycarbonate disc. Don’t know if that’s correct but you’re right, that’s what the diagram shows.
That is correct. That is the construction of a CD.
Keep in mind that the diagram does not illustrate the relative thicknesses of the various layers. The polycarbonante is 1.1 to 1.2 mm thick. The reflective layer is just a few nanometers thick. Protective lacquer is 6 - 12 microns. Ink (label) is just a few microns.
Figures 2,3 at this link has a better diagram: https://www.clir.org/pubs/reports/pub121/sec3/
Thanks, that is better.
In my old car you slid the CD into a slot, and so you couldn’t read the label until you ejected it. However I expect having room on the label for information and artwork had a lot to do with it. I also expect the design of portable CD players was simpler if you didn’t have to put the laser in the lid, whereas phonographs were easier with the needle on top.
Gee, thanks!
A CD player with the original sort of “tray” disc loader has to lift up the disc slightly, so that it doesn’t get scratched all to hell as it spins. Once the drawer is closed, the motorized spindle rises up from below into the center of the disc, lifting it a couple of millimeters up out of the tray. That part has to be on the bottom, unless you want to get some kind of mechanism that grabs and lifts the disc from above (which seems more complicated).
To read the disk, you then need a laser that can move from the inside of the disc towards the outside, so you need a second motor drive unit. In principle, this could either be above or below the disk. But you already have a motorized spindle below the disc, and nothing else, so you might as well put the laser & its motor drive below the disc as well and read the disc from below.
Since it has to pinch the disk from above and below, not just lift it, there’s no reason why that entire mechanism couldn’t be upside down or sideways as was the case in 100/200 disk changers.
If all it did was lift the CD, there wouldn’t be anywhere near enough friction to spin it, and even if there was, it would almost certainly wobble.
Whoever did that (possibly Phillips, the held the CD patents), I’m sure glad they did. Made it a lot easier to use CDs.
Wish somebody had done the same on USB plugs! It’s very hard to tell at a glance which side goes ‘up’, so you’ve only got a 50-50 chance of inserting it the right way on the first try. And the symmetrical design of the plug body gives you no clue. (Supposedly, the USB logo is supposed to be shown only on the top side of the plug. But as this is usually molded in black plastic on a black plastic plug, it’s close to invisible, and useless to most users.)
Actually, there is an easy way. The hollow half of the plug is up, the half filled with plastic is down. This works almost all the time. My old laptop had the USB ports on one side upside down, but then all the ports on that side were - the VGA monitor and Ethernet ports were upside down, too. The ports on the opposite side were right side up.
This means I have to look at the plug to assure correct orientation before attempting to insert it, thus making daily life a miserable slog. Happily the problem has been solved: Apple’s lightning connector can be inserted either way, and so can the USB-C connector. OK, yep, you still have to basically align the long dimension of the plug with the long dimension of the socket, but that’s easy at a quick, casual glance without putting my glasses on.
Please pardon the hijack, but why can’t the players be repaired when they stop working?I’ve got about a dozen like that and hate having to buy another $40 boom box.
That’s your answer.
How much is a skilled technician’s time worth?
Depends on what’s wrong with them. I’ve gotten portable CD players to work again by cleaning the laser lens (with a CD laser lens cleaner).
For something more than just a dirty lens, I suspect it could theoretically be repaired, but it’s usually cheaper/easier just to buy a new one.