El 09/06/2017 a las 19:16, Jeff Liebermann escribió:
On Wed, 31 May 2017 14:29:47 +0200, 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?

TIA

This might be more than what you might want:
"List of failure modes and mechanisms in Laser Diodes"
http://www.diee.unica.it/~vanzi/ListFailures1of2.pdf
This is from 2004, so some things will be out of date. The chart on
Pg 2 showing various failure mechanism might be a good start. I
haven't had time to read through the report.

What little post mortem testing I've done seems to point to a
deterioration in laser output, but I've never investigated further and
some crude measurements using a flat photodiode as a light meter.

This may also be helpful:
"Notes on the Troubleshooting and Repair of Compact Disc Players and
CDROM Drives"
https://www.repairfaq.org/REPAIR/F_cdfaqd.html


The first link is too technical, even for a physicist like me.

The second is very helpful, although somewhat discouraging. I'd like to
know if recent Sony spare parts are more reliable than eight years ago
or it's better to toss the devices and buy better ones (Denon?).

Thank you.

--
Saludos
Miguel Giménez