El 01/06/2017 a las 1:16, whit3rd escribió:
On Wednesday, May 31, 2017 at 11:50:43 AM UTC-7, Trevor Wilson wrote:
On 31/05/2017 10:29 PM, Miguel Giménez wrote:

In the last years I have changed twice the laser unit of my Aiwa CD
reader and once the unit of my mom's Sony reader. The three were
original spare parts, and the three died months after.

Why this happen? Do I need to adjust laser current after change? Are
they basically unreliable?

**IME modern lasers are not reliable devices. The older ones were very
reliable. Why? Dunno exactly. If you look at an old laser from a Sony or
a Philips CD player, you will likely see a very carefully (hand
assembled?) laser unit...

Usual failure mode for a surface-emitting laser is some kind of dirt migration in the
surface. This has NOT been getting worse, the chemistry and material preparation
is as good now as it has ever been, and even UV semiconductor lasers are working
well for long periods of time.

Another possible reason for failure is ... lack of use. The normal electrical bias during
operation is intended to keep sweeping impurities out of the sensitive region.
If you just store the unit on the shelf, and DON'T operate it for a few hours
a week, the (equivalent of) dust bunnies just pile up.

The implication is, use your CD/DVD/BD readers and burners every week or so. They
might just go bad on the shelf otherwise.


Certainly the Sony unit was seldom used, and the Aiwa use was greatly
reduced after first failure to preserve the laser (sigh!). In both units
the new part failures happened after some weeks of inactivity.

Thank you.

--
Saludos
Miguel Giménez