OPC power and dying/dead CD Recordable drives

You might notice that one day you get the dreaded OPC Failed or Power Calibration Failed on your trusty CDR drive when no other software, hardware or media has changed. You go through several discs wondering what to make of this, then change to a different brand of media with the same result.

The laser diode in a CD drive has a finite lifetime during which the laser output for a given amount of power flowing through it will gradually decrease. The useful life of the laser pickup depends upon the average power flow through the diode; a high power flow accelerates the degeneration of the laser beam. Eventually, this renders the pickup unusable because the circuit has a laser power ceiling at which point it will refuse to increase the power through the diode any more so that it avoids immediately burning out the diode. If your deck has reached the laser power ceiling, but the laser output is still low enough to render your discs unreadable, it is time for a new deck.
A CD pickup has a compensation circuit that sets the laser power to the minimum necessary to get a clean read. The laser power is increased when the disc is dirty or the lens is dirty. Cigarette smoke and dust from a poorly sealing drive will dirty the lens and increase the average laser power, thus shortening its life.

You might notice that even though your burner no longer writes discs, it will still read them. This is because the laser requires far more power to write a disc than to read it. Therefore, a weak pickup (one which has a low laser output to laser power ratio) will very often still function as a reader even when it is no longer useful as a writer.

Another fact to note is that the laser requires more power to write reliably at higher speeds. This means that a higher average write speed will mean a shorter laser life. It also means that if you have a CD writer that is failing power calibration at its maximum write speed because it is nearing the end of its useful life, you may be able to get extended service from it by simply lowering the write speed. If the OPC passes at a given speed, it is quite likely that the disc will be successfully written.

Also, just because a disc failed OPC does not mean it must be discarded. CD recordable discs have 100 OPC segments. So a disc that fails OPC in one recorder can simply be reused in another one, or in the same recorder at a sufficiently lowered speed.

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