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
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
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
May be a focus problem unrelated to laser?
Likely.
Peter Wieck Melrose Park, PA
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.
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
This might be more than what you might want: "List of failure modes and mechanisms in Laser Diodes" This is from 2004, so some things will be out of date.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"
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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
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.
Best of luck with them.
Peter Wieck Melrose Park, PA
us and/or counterfeit part issues happening here. All of which are entirely possible and nothing to be ashamed over.
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.
-- Jeff-1.0 wa6fwi http://www.foxsmercantile.com
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