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What does the 'line out' cable on my dvd drive do? Answered

 I've got this dvd drive and on the back there are four pins in which a cable can be plugged tagged as 'line out' on the sticker on top of the drive, however i can't see how this cable could contribute to the working of my dvd drive. But without it some things don't work, for instance installing windows is impossible without this cable.


Once upon a time, audio cards required an analog feed from the CD drive in order to handle audio.  Suddenly, someone finally came to the conclusion that it made absolutely no sense to do it this way, since it requires the CD drive to convert digital to analog, only for the sound card to convert it from analog to digital, then back to analog for the speakers.  Media players were then written to read the CD as digital data and leave the A/D conversion to the sound card.

However, almost all CD and DVD drives still have this analog output as a leftover from those times (I'm guessing the manufacturers' excuse is for compatibility reasons).  I'm actually shocked that you aren't able to get Windows to recognize the drive properly without it, as it is completely irrelevant to the functionality of the drive - or, for that matter, Windows seeing the drive through the IDE (which is how it uses the drive anyhow).

I'm guessing either your version of Windows, motherboard, (integrated) audio card, and/or media player of choice is severely outdated.  This cable hasn't served much of a purpose for eight years.

Incidentally, Nacho is right about the pin out.  The only thing I'll clarify is that the center pins are both common rather than L- or R- (a subtle difference, but the output is unbalanced, meaning that those pins do not change voltage).

MahavishnuMan's answer is dead on.

.  The only place I've seen "line out" used is for a 1Vpp (one volt peak-to-peak) analog signal. Eg, audio signals between stereo components. With that in mind, I'm guessing that your four wires are L+, L-, R+, and R-, and, as per lemonie, go to your soundcard.
.  As with lemonie, I have no idea why anything to do with computer data discs would not work without the line out connector plugged in.

I'd say "line out" is plain CD audio for when the drive id playing music-CDs. This can feed to the sound system on the mainboard or what you might have in a PCI slot.
Why installing Windows doesn't install is odd because it should only be using the thing as a logical drive via the EIDE connector.