i have a cd-rom drive ( samsung 52x ide ) on a WinME machine.
It’s been working alright for months…then suddenly yesterday i hear a big plastic breaking sound…realize that it’s something to do with my cd-rom drive…
to my amazement…the cd-rom, a game cd i inserted to play, just shattered inside…had to unplug and dismantle the whole drive to get the plastic shards out…the biggest piece was only about an inch long…
there might have been a voltage surge at the time…not sure though…and the drive was hot, but not unreasonably so.
so was it heat ? or the laser ? or the voltage spike ? or a combination ?
One key to making CD rom drives faster is that you make the disk spin faster. Modern CD rom drives whip that little disk around awfully darn quick. I suspect that what you have here is not a failure in the CD drive, but a failure of the CD to keep itself in one piece. Perhaps it was just a plain old ordinary weak spot in the plastic, or maybe the disk was out of balance which aggrivated the problem.
Power spikes and surges are filtered out by the PC’s power supply. The chips on the motherboard are far more sensitive to spikes than the motors in the drives.
The laser doesn’t have enough power to melt plastic.
I’m an electrical guy, not a mechanical guy, so I don’t know what kind of role heat may have played in the event. I have it in my mind that heat makes plastic kinda gooey, it’s cold that makes it brittle, but I’m definately not a materials person. In the long run, heat is one of the worst enemies of your computer system. If you cool the drive down it will last longer.
But it does have enough energy to make the CD get pretty warm. I’ve taken CDs out of my computer after continuous reading and they can be almost hot. Don’t know how this would affect the plastic though. I suspect flaws in the plastic, as others have suggested. But it’s only a WAG.
I’ll have to ask my brother-in-law, he’s an engineer at a Sony CD manufacturing plant, he’d know for sure. But he lives in another city and I only talk to him once every few months, so I won’t be able to provide a timely answer. Sorry.
The CD plastic was probably stressed beyond it’s limits either in manufacturing or during handling. I have damaged CD’s through rough handling and later had them come apart at the pre-existing stress cracks even while being handled gently. I have also had them spontaneously crack into pieces after sitting in a hot car without being touched. If the CD came apart while being stressed during spinning this is a bit unusual but not surprising.
I’ve often wondered if the pursuit of ever-higher spin speeds would eventually result in either damage to the disc or maybe just distortion, making it difficult for the laser to track.
I’d say that there was probably a minor crack or imperfection in the plastic of the cd and under the forces generated by spinning it 52 times faster than it was designed to go, the crack opened up and propagated across the disk.
Really? I’d be surprised if the low power lasers used in CD-ROM drives could make a warm spot on a single spot, much less a spinning disk. I think it’s much more likely that a disk gets hot via convection from the power supply or drive motor or conduction from other drive components.
I don’t know for sure, and I’ll probably have to disassemble an old drive just to find out, but I’d bet that most of the heat in the drive is not from the laser.
The “X” rates often reflect more than simply RPMs. IIRC original CDROM 1X spin rates were around 500 RPM and current 52X spin rates are around 7200 RPM.
The G force at the edge of a spinning disk, RCF = 0.00001118 x radius(cm) x RPM[sup]2[/sup]
For a 12cm diameter CD spinning at 7200 RPM this works out to about 3773 gravities. http://www.labcentrifuge.com/applications/rpm_vs_rcf.html
That’s a pretty good stress multiplier.
Of course, xash is no doubt religiously scrupulous about cleaning CD’s, but I’d ask, “Was the CD in question cleaned within hours before the calamity?”
Certain chemicals used as cleaners can destroy some plastics. I specifically recall once using automotive brake cleaner to degrease a plastic part of something-or-other and watching some minutes later as the little pieces of what used to be that plastic part spilled into my hand. The effect was not immediately apparent – the part stayed together for a while – but when it happened, it happened all at once. The plastic part completely disintegrated.
Chas E., I’ve had the IR laser from a CD player shine on my flesh, focused and unfocused, and they just don’t really produce any noticeable heat. Even after an extended time. I suspect that the disk gets warm simply from the heat transfer in the drive - the drives can get pretty warm themselves, just touch the top of one that has been on for a while.
According to a couple links I just looked up typical CD lasers put out between 0.3 to 1 mW at the objective lens, although the laser may put out as much as 3 to 4 mW at the diode itself. 1 mW is not really very warm.
OK, let’s assume the CD is polycarbonate. That has a specific heat of 1256 J/kg*K. Let’s assume that a CD weighs about 10 grams. So we would need 12.56 J to raise the temperature of a CD by 1 K. OK…now, 1 mW delivers 0.001 J/second. Let’s assume that half of the laser’s energy is absorbed by the CD, and half is reflected. That gives us 0.0005 J/second.
So…we need (12.56J/0.0005 J/s) = 25,120 seconds to raise the temperature of the CD 1 K as a result of the laser energy - or about 6.98 hours. 1 K is about 1.8 F temperature differential. This also assumes that the process does not transfer heat with the environment of the CD player - that is, that all heat delivered to the CD remains in it.
So…unless I really missed something, I think you may be incorrect here on this.
Also, drives above a certain “X” rating (6X, if I recall correctly) spin at a constant speed in “high speed mode” instead of varying the drive motor speed as the head seeks in and out to maintain a constant bit rate (which is unimportant for data use but critical for audio use).
On the OP, I’d be very surprised if the failure wasn’t due to a fracture or other mechanical defect in the disk.
“As many of you may already know, optical drives generally come in two flavors of spindle motor spin rate: Constant Angular Velocity (CAV), and Constant Linear Velocity (CLV). In a nutshell, CAV drives spin at a constant rate. Because the inner tracks of a CD are much smaller than the outer tracks, a CAV drive will have slower read rates at the inside of a CD than at the outer edge. CLV drives, however, vary the spindle motor’s RPM according to where on the CD the information is being read. The motor will speed up at the inner tracks and slow down at the outer tracks. This creates a linear read rate across the CD. Most of today’s CD-ROM drives are CAV. However, under certain conditions a CAV reader may operate in a CLV-fashion. For example, many drives will read CD-RW media or extract digital audio at CLV. This could be for compatibility, error-correction, or performance reasons. We will specify when CAV units revert to CLV. Finally, it should be mentioned that there is what is called P-CAV. This is partial constant angular velocity. This is when a drive starts reading a CD in a CAV-fashion at the inner tracks, then when it reaches a specified speed, reverts to CLV for the remainder of the CD.”
“As many of you may already know, optical drives generally come in two flavors of spindle motor spin rate: Constant Angular Velocity (CAV), and Constant Linear Velocity (CLV). In a nutshell, CAV drives spin at a constant rate. Because the inner tracks of a CD are much smaller than the outer tracks, a CAV drive will have slower read rates at the inside of a CD than at the outer edge. CLV drives, however, vary the spindle motor’s RPM according to where on the CD the information is being read. The motor will speed up at the inner tracks and slow down at the outer tracks. This creates a linear read rate across the CD. Most of today’s CD-ROM drives are CAV. However, under certain conditions a CAV reader may operate in a CLV-fashion. For example, many drives will read CD-RW media or extract digital audio at CLV. This could be for compatibility, error-correction, or performance reasons. We will specify when CAV units revert to CLV. Finally, it should be mentioned that there is what is called P-CAV. This is partial constant angular velocity. This is when a drive starts reading a CD in a CAV-fashion at the inner tracks, then when it reaches a specified speed, reverts to CLV for the remainder of the CD.”