Why do laser blocks die?

MisterFishey

AK Subscriber
Subscriber
I've always wondered this. Electrolytic capacitors have the fluid in it that dries up, resistors degrade, and the contacts on relays get worn down and oxidize. But why do laser diodes die? LEDs have a longer lifespan than 20 years, so why don't laser blocks? This is sheer curiosity here. :yes:
 
Eseentially, they run pretty hot and heat kills semi-conductors. But, too, often the problem is not the diode but the servos - the voicecoil support becomes too flimsy and the LASER can't focus poperly.

DH

I've always wondered this. Electrolytic capacitors have the fluid in it that dries up, resistors degrade, and the contacts on relays get worn down and oxidize. But why do laser diodes die? LEDs have a longer lifespan than 20 years, so why don't laser blocks? This is sheer curiosity here. :yes:
 
Eseentially, they run pretty hot and heat kills semi-conductors. But, too, often the problem is not the diode but the servos - the voicecoil support becomes too flimsy and the LASER can't focus poperly.

DH

So if you put a really small fan near the laser, it would last longer? And is it even possible to repair the burned parts when they go up?
 
A lot of the time, the machine fails not due to the laser buring out but it's related components, either in the laser assembly or associated circuits. I have thought long and hard about attempting a laser diode transplant, but it's not as easy as it sounds as the block is aligned at the factory and without the proper jigs, nearly impossible to do. However, many lasers have lasted 20 years of moderate to low use, I am sure more than the manufacturer would have liked. I really wish a company would make aftermarket lasers so that we may keep our beloved higher end machines running.
 
A lot of the time, the machine fails not due to the laser buring out but it's related components, either in the laser assembly or associated circuits. I have thought long and hard about attempting a laser diode transplant, but it's not as easy as it sounds as the block is aligned at the factory and without the proper jigs, nearly impossible to do. However, many lasers have lasted 20 years of moderate to low use, I am sure more than the manufacturer would have liked. I really wish a company would make aftermarket lasers so that we may keep our beloved higher end machines running.

So what you're saying is that it is possible to revive a "dead" laser block. Interesting. And by proper jigs do you mean a scope?
 
It is all assembled by VERY unbelievably high precision automatic assembly machinery.

There is circuitry to control the power output automatically, and if it can't clear the threshold any longer, kaput.

Cheap driver electronics can inadvertently give them sub microsecond spikes of too much drive (during turn on - turn off), not good... and if even a good driver pushes a weak one too hard (like to write instead of reading), the damage accumulates very quickly to the point of loosing enough power to even read the disk.

Remember, it's just not a semiconductor junction, there are end facets (mirrors, even if not coated) and geometry involved for the laser cavity, and while the semiconductor material may stand up to the heat, what about the mirrors? The power densities at that size are almost unbelievable...

It CAN end up being more of a LED than a laser.......
 
So what you're saying is that it is possible to revive a "dead" laser block. Interesting. And by proper jigs do you mean a scope?

Possible, yes. Practical, no. The laser assemblies are very complex and unless you have very expensive equipment and knowhow, forget it. It would be easier to buy a donor unit to replace the laser diode.

That said, there "may" be some laser assemblies that can replace each other, for example, a Sony KSS-271A can replace a KSS-270A. In fact I have a hunch that a KSS-270A can sub for a KSS-151A and KSS-272A, but I have yet to confirm this.
 
A lot of the time, the machine fails not due to the laser buring out but it's related components, either in the laser assembly or associated circuits. I have thought long and hard about attempting a laser diode transplant, but it's not as easy as it sounds as the block is aligned at the factory and without the proper jigs, nearly impossible to do. However, many lasers have lasted 20 years of moderate to low use, I am sure more than the manufacturer would have liked. I really wish a company would make aftermarket lasers so that we may keep our beloved higher end machines running.

I tried this 3 times, removing a good diode from a donor unit and installing it in the laser block. Never got it to work.:thumbsdn:
 
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