I’ve got a PLS5 laser level and the beam fades after turning it on for a short while. The manufacturer says the “diode” is probably on the way out. Any experience out there with this issue? Also, how long is the diode supposed to last? (The level is nine years old). Any ideas where to look for objective information on this problem? Thanks.
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I assume he means the laser diode. I know they do have a finite life, but can't say what that is or what the typical failure mode is.
Fading after being turned on for awhile suggests that heating is the culprit. I'd suggest opening it up as best you can and clearing out any dust that may be blocking airflow.
I thought of heating first thing, after changing the batteries numerous times that is. I called the manufacturer and that was my first question, about heating. They say it's far more likely that the useful life of the diode is up. These are the symptoms anyway.
Since diode life is a common problem they offer a newer version of the product for half the price with a trade in. The newer version resolves a couple of design issues I had with the original so I think I'll go that route. It's a really good product all in all, highly accurate. With the design improvements I'm guessing I'll be happy.
I guess as the manufacturer, they would know but most low voltage LEDs have life expectancies in the tens of thousands of hours. I don't know what the driver circuit is like, but I'd be more inclined to look there, although it's most likely more expensive to replace than the LEDs themselves...PaulB
http://www.makeabettertomorrow.com
http://www.finecontracting.com
It's not a LED, it's a laser.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
http://en.wikipedia.org/wiki/Laser_diode
http://www.repairfaq.org/sam/laserdio.htm#diodlm6
"While the typical 5 mW laser diode may have a specified life in excess of 100,000 hours ..."
Not looking fpr a peeing match, just used to referring to laser diodes as LEDs, which was originally their derivation.PaulB
http://www.makeabettertomorrow.com
http://www.finecontracting.com
Yeah, and I'm not wanting to get into a fuss either. It's just I recall reading that the diminishing output from laser diodes as they age is a problem for fiber optic communications.But what's odd about the OP's scenario is that the output drops as the unit "warms up". Makes me think that this case, at least, is not due to diode aging.Of course, the guy on the phone may have simply meant that the circuit board that carries the diode goes bad with age.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I agree, that's why I was thinking the driver but in either case probably not worth repairing.PaulB
http://www.makeabettertomorrow.com
http://www.finecontracting.com
Yeah, he got nine years out of it, which is probably more than one should expect from such a tool.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
The manufacturer says the "diode" is probably on the way out.
That's an odd comment. Semiconductors, including LED and laser diodes, generally will fail early on if they are defective. Once they run 90 days or so, they will usually run essentially forever. We have lasers diodes in the lab far older than that, still fine, in daily use.
The fading after turn-on sounds more like a passive component problem. Capacitors are notorious for this - my guess (as an EE) would be that a capacitor is getting old and leaky.
If it's the cap, you can identify it, and can solder, it's a cheap, easy fix.
Thanks Woodturner. There's always the possibility that the guy representing the manufacturer is disseminating misleading info. He claims the diode on all these lasers we buy for construction purposes have a finite life span. The guy at the tool store says lasers he sells don't last forever also, however, he didn't claim it was the diode problem.
This particular laser is sealed in such a way as to discourage having a look at what's going on inside, though I'm assuming looking at the innards wouldn't do me a lot of good as I don't know what's what and how to test components.
I am curious as to whether or not other laser owners have experienced similar problems and what the diagnosis was. There sure have been a lot of those things sold so there ought to be some ancedotal evidence out there as to longevity.
He claims the diode on all these lasers we buy for construction purposes have a finite life span. The guy at the tool store says lasers he sells don't last forever also, however, he didn't claim it was the diode problem.
A couple of factors could be contributing to this. Excessive heat is the bane of electronics - if the cooling is marginal in the product, use in hot environments would accelerate electronic failure rates. Construction is generally a pretty tough environment, so there may also be other factors that decrease the life. As I mentioned, the units we have are in the lab - a fairly stable, benign environment.
Didn't mean to suggest they were lying to you, just offering another perspective, experience, and reaction to the comment.
where to look for objective information on this problem?
Google Mil-hdbk-217 - gives you lifetime of all kinda stuff based on reported failures over the last many decades (since before laser diodes even)
BTW, click on your name, fill out your profile.
Laser diode lifetime is somewhat less in Denver or ABQ than in LA or NYC or NO. (total dose)