YDL3 and iMac CDROM Drives

[Tim Seufert]

On Sunday, May 11, 2003, at 07:02  AM, Jeremy R. Gilby wrote:

> I grew up with those kind of drives also, especially my legacy CD
> players.  However, from the looks of the hardware, the iMacs are not
> built for that kind of manual assistance.  (It takes a lot of force to
> encourage the servos to retract the tray)  I can only see that repeated
> use of this method will slowly wear down the mechanical parts of this
> aparatus.

You are worrying way too much about this.  The amount of force you have 
to use varies a great deal from one drive model to the next.

Please understand that with most (if not all) drives you are simply 
pushing back against the torque of a stalled DC motor.  The main way to 
hurt a DC motor is to get it hot.  How do you get it hot?  The best way 
is to stall it -- DC motors have the property of developing maximum 
torque AND drawing the peak possible power when stalled.

Combine that with the fact that users sometimes leave trays open 
indefinitely, and any well designed optical drive will have gearing 
designed to withstand the motor's peak torque forever, and a motor 
which cannot overheat itself when stalled.  If you're worried that the 
force you use might hurt this mechanism, you should go a step further 
and never leave the tray open any longer than necessary, because as 
long as it's open it's under stresses not terribly different from when 
you push back on it...