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Learn From Mistakes That Can Happen To Anybody...

jayrob

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How about a thread where you share a mistake that is easy to make, so that others can learn to watch out for... Before they make the same mistake?



Please share your experience for others to learn from! :)

I'll start this off with a very costly mistake that I made, and killed a $300 dollar diode...

This was back in the days before the PHR's, and I was trying to be the first to build a hand held blu-ray over 50mW's.

I had a $300 dollar BWU-100A drive. The harvest went fine on this one, and I was plotting it at 10mA increments...

So it was just a matter of:

* Turning off the laser
* Turning off my DMM
* Disconnecting the diode
* Then connecting the test load to re-set the current
* After re-setting the current, shorting the leads (just to make sure)
* Then re-connecting the diode to take the next measurement

Well, the mistake came when I got comfortable after 6 or 8 measurements...

I got a little too comfortable... (and maybe in a hurry)

What happened was, I turned off my DMM before I turned off my laser! Which would not have killed the diode, except in a 'split second', out of sheer reflex, I turned the DMM back on. This is what instantly killed the diode. Because the driver had charged the cap, and as soon as I turned my DMM back on, it popped my diode...

That hurt...

But it can easily happen to anybody. Anyway, I learned a good lesson. Too bad it wasn't with a less expensive diode!

As we all know, diodes are very sensitive. And can be damaged, even from the spark off the tip of your finger.

If you kill a diode, try to see if you can at least figure out what exactly happened. That way you will learn from it.

That's the only thing that I have taken from my loss of that diode. That at least I understood what happened...
 
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daguin

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Re: Mistakes That Can Happen To Anybody...

I removed, destroyed, and trashed a perfectly good >$300 diode because I forgot that the flexdrive will "shut off" when the voltage from the battery gets too low.

It was a 6X back in the day when we were still buying >$300 drives to harvest the diodes from. The diode was in a Kryton Smooth with a flexdrive. I was "pushing" the diode so was always anxious when I turned it on the first time that day. Well I turned it on and it was dark.

I cried my tears and changed the diode (destroying it in the process). When I turned on the laser with the new diode, it was still dark. I thought back through what I could have done wrong to blow the new diode when I remembered about the "shut down" threshold of the flexdrive.

I recharged the battery and everything was fine. Only then did I realize that the other diode was fine as well.

Always check the battery first!

Peace,
dave
 

jayrob

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Re: Mistakes That Can Happen To Anybody...

Oh man Dave... That hurts!

Great lesson, thanks for sharing...
 

Freitsu

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Re: Mistakes That Can Happen To Anybody...

Not so costly this one but I thought I'd share it anyway.

When trying to pressfit a LPC-815 with the back of and AixiZ housing into AixiZ housing, back somehow slipped and cut off the + on diode. Anyone know how to salvage those kind of diodes btw? :)
 

jayrob

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Re: Mistakes That Can Happen To Anybody...

That's another good experience to share...

I did the same thing with another expensive diode! It was because of being too lazy to go downstairs in the garage and use the vice like I usually do...

I thought I would just use my C-clamp that was in my office tool box. Well that was the last time I ever used the C-clamp to press a diode. Because on the final tightening, the press tool took a little 'spin' with the C-clamp as I twisted it tight.

No prizes guessing which pin I 'sheered off'... Yep, the positive pin.

I couldn't fix it. There may be some who are talented enough to fix such a tiny thing, but I wasn't able to fix mine...
 

Freitsu

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Re: Mistakes That Can Happen To Anybody...

I tried fixing it by carefully trying to put a tiny solderblob on the end but it's didn't work so well...

Lesson learned, I got a vice the next day! :D
 

Cheech

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Re: Mistakes That Can Happen To Anybody...

On my first diy i got the ddl driver ready with high resistance connected to a 24x red dvd burner diode, turned it on with no aixis module and it wasn't bright at all looking toward the can at about a 15 degree angle. So I added more resisters in parallel and tried it again and BAM! The beam caught me in my right eye. I had no idea that the beam diverged that much. Luckily there was no permanent damage but it could have been real bad. It was my first build so I had the mindset that what comes out of the front of the diode should be a laser beam right...wrong.
Hopefully this will keep someone from making the same mistake
 

jayrob

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Re: Mistakes That Can Happen To Anybody...

All of this is great stuff that others can learn from...

Thanks for sharing!

Keep those experiences coming in! :)
 

Monco

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Re: Mistakes That Can Happen To Anybody...

this is going to help me a lot when i do my first build :] i'm going to stay glued to this thread
 
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Re: Mistakes That Can Happen To Anybody...

Never turn your laser on with the dust cap on. 2 people that I know of, and myself have fried PHR diodes this way.
 

aXit

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Re: Mistakes That Can Happen To Anybody...

Never turn your laser on with the dust cap on. 2 people that I know of, and myself have fried PHR diodes this way.
Thread about this? Not that I do it often, but I've done it once or twice accidentally with no effect.

What happens to the diode?
 

chipdouglas

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Re: Mistakes That Can Happen To Anybody...

i'm always in a hurry for no apparent reason.... i take short cuts all the time.. but i am learning to slow way down after:
i have killed a few diodes, phr and 6x by being sloppy with my soldering and handling of the units and snapping of a diode pin or 2.
i have ruined 1 phr by my previous extraction methods, now i use the cold method.

michael
 
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Re: Mistakes That Can Happen To Anybody...

Thread about this? Not that I do it often, but I've done it once or twice accidentally with no effect.

What happens to the diode?
Not sure, but other people have said it happened to them also, they just didn't put 2 and 2 together. IgorT also advises not do it, and he obviously knows what he is talking about. I guess you just got lucky.

It might be heat, or a reflection. I think it depends on how the laser is focused at the time. That's why it doesn't happen to everyone. This is only a guess.
 

Crazy Jay

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Never rush things when soldering. I've messed up a few drivers on those cheap 5mw green lasers. On a larger scale the loss will be even worse!
 

photonaholic

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Showing my age, but I once rolled a perfectly good HeNe tube onto the floor by turning the stereo up too loud.

The woofer vibrations were enough to set the tube rolling, and as soon as it hit the floor, it was toast.

It was one of those nice high end NEC tubes with the killer anodized spun aluminum housings. They were $200 on the surplus market back then.

It still lased at first, but when I picked it up, the housing shocked me. I could feel the HV, then as air seeped in through the new cracks in the glass it stopped lasing altogether.
 

jaycey

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Clean your soldering iron tip after EVERY solder joint.
Bad solder joints has cost me at least 2 diodes.

Make sure the batteries in you Multimeter are well charged or fresh.
I had untold trouble working out why my diodes looked so dim until I changed my batteries and realised all my DDL drivers were set around 50% under what I thought they were!
 




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