Why CD laser unit fails so often?

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Hi

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

--  
Regards


Re: Why CD laser unit fails so often?

Quoted text here. Click to load it


Never had or observed this problem per-se. Many times I have seen the outpu
t level of the laser poorly adjusted, poorly focused or not precisely align
ed, especially if resulting from a home repair. Admittedly a small sample,  
perhaps about 20 players in all.  

Peter Wieck  
Melrose Park, PA

Re: Why CD laser unit fails so often?


Quoted text here. Click to load it

Quoted text here. Click to load it

The replacements worked OK for some months, then failed abruptly. The  
symptom was always: insert disk -> some seconds trying to read disk ->  
disk ejection. May be a focus problem unrelated to laser?

Also, there were neither smokers nor floating dust near the devices.

--  
Regards


Re: Why CD laser unit fails so often?


 May be a focus problem unrelated to laser?  

Likely.

Peter Wieck
Melrose Park, PA


Re: Why CD laser unit fails so often?

Quoted text here. Click to load it


Don't know about your particular drives, but anybody who did any kind of au
dio work in the 90s knows that Sony lasers were/are pure, unadulterated shi
t.  I'm being kind here.

There were tons of otherwise very nice Aiwa three CD carousel combo stereos
 that had decent power and respectable sound (given the market) and enough  
LEDs flashing to keep the Walmart buyers enthralled.  Unfortunately, they a
ll came equipped with Sony lasers.  We pulled the plug on doing these after
 the first few failed and recommended that our customers use these for "gar
age" radios.

Now I've heard that there were/are Chinese counterfeits for these and this  
might explain repeat failures, but it doesn't explain why so many Aiwa and  
Sony brand CD players came in for weak or dead lasers in two years.


Re: Why CD laser unit fails so often?

Quoted text here. Click to load it

Quoted text here. Click to load it

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


Re: Why CD laser unit fails so often?

wrote:

Quoted text here. Click to load it

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

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Why CD laser unit fails so often?


Quoted text here. Click to load it

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


Re: Why CD laser unit fails so often?


Quoted text here. Click to load it
  
Quoted text here. Click to load it

I don't know. At this point, I have six (6) CD changers and one single-disc
 player in the inventory, Five changers are Sony, including two 200-disc ch
angers, one is a Yamaha. The single disc player is a Revox. None of them ha
ve had any laser problems over the last many years of use. One of the 200-d
isc changers has run for weeks at a time 24/7 as it feeds my transmitters,  
mostly in the winter. All the Sony devices are thrift-shop purchases for US
$25 or less, so not even 'babied-from-new' as is the Yamaha, or second-owne
r as is the Revox.  

So, I suspect some sort of user-error, installation problem, drifting focus
 and/or counterfeit part issues happening here. All of which are entirely p
ossible and nothing to be ashamed over.  

http://www.ralph-toman.de/cd_player_eng/cd_player_eng.htm is a rather tech
nical discussion on "how-to" do the various adjustments for various CD play
ers that might be helpful.  

Best of luck with them.

Peter Wieck
Melrose Park, PA  


Re: Why CD laser unit fails so often?
On Tuesday, June 13, 2017 at 8:22:46 AM UTC-4, snipped-for-privacy@aol.com wrote:
  
Quoted text here. Click to load it
us and/or counterfeit part issues happening here. All of which are entirely
 possible and nothing to be ashamed over.  
Quoted text here. Click to load it


If only.  I stopped repairing CDs when the prices dropped to a certain leve
l, but Sony lasers, at least in the lower end machines, are and were junk.  
 Since I've bailed on repairing them many years ago, I've read stories in o
ur private association site of other servicers still repairing them having  
several new Sony sleds DOA or having other issues.  These are most likely a
ftermarket or counterfeit as I can't believe Sony would still be making rep
lacement parts.

None of this excuses the original parts that failed in great quantity, or a
ddresses the possibility that higher end Sony CD players (changers for inst
ance) didn't use a better quality laser assy that were not short lived.  On
ly by knowing production numbers and comparing them with repair statistics  
could we shed any light on them.



Re: Why CD laser unit fails so often?
On 6/13/2017 8:23 AM, John-Del wrote:
Quoted text here. Click to load it

<http://www.theonion.com/video/sony-releases-new-stupid-piece-of-shit-that-doesnt-14309



--  
Jeff-1.0
wa6fwi
We've slightly trimmed the long signature. Click to see the full one.

Site Timeline