SCSI CD burner

[Tony Duell]

> 
> At 02:35 PM 9/16/2006, CRC wrote:
> >The basic problem with commercial CD burners/players is that they  
> >keep the laser diodes on when powered, although at the low power  
> >required for reading. The life of run-of-the-mill laser diodes is on  
> >the order of 10,000 (10.000) hours. Consequently, if you keep your  
> >system on all the time you can expect one to two years of useful life  
> >from the beast (some longer, some shorter).  From <http://www.wtec.org/ loyola/opto/ad_rohm.htm>:
> 
> That document dates from 1994.  You'd think that manufacturers would
> want to increase MTBF and eliminate failures as quickly as possible,
> so I find it hard to believe that LEDs are left on inside today's
> CD/DVDs just because it's hard to turn them off and they don't want
> to improve lifetimes.  This info may be entirely relevant for 
> 1980s drives, who knows?  What sorts of other ancedotes and
> claimed facts do we have?

It should be very easy to check this. Those IR detector cards sold for 
testing TV remote controls will detect a CD player or CD-ROM laser. Has 
anyone tried holding one over the pickup of a CD-ROM drive?

I know for a fact that my ancient Philips external drive, which is 
actually based on an audio CD player, turns off the laser when not 
required. When there's a chance you've inserted a disk, it powers up the 
laster, tries to find the focus point, if it finds it, it spins up the 
disk and reads the TOC. If not, it powers down the laser. This is, I am 
pretty sure, shown in the service manual.

-tony