Anyone know the power of DVD Reader LDs?

Hi guys!


Since i also have a few CD-RW/DVD-ROM combo driver laying around, i was wondering if anyone knew what the power ratings of DVD reader LDs are? For example a 16x DVD reader.. Or an 8x?

I know they're not enough to burn anything, but i believe, they should at least make nice laser pointers...


So should i treat them as if they were 5mW? 10? What current should i be driving these with?


Any info would be greatly appreciated.. I just need an approximation..


Thanks!


Igor

yep DVD readers are not high powered, but are sometimes IR(invisible), so if you hook them up, and nothing happens, you have either blown it, or it is IR. You should treat them like any laser diode if you want them to work, wear antistatic straps and all! as for the current, every diode is different, so you will have to find that out for yourself! start low and work up!

things said:

yep DVD readers are not high powered, but are sometimes IR(invisible), so if you hook them up, and nothing happens, you have either blown it, or it is IR. You should treat them like any laser diode if you want them to work, wear antistatic straps and all! as for the current, every diode is different, so you will have to find that out for yourself! start low and work up!

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Thanks!

I already took one apart, and it has two LDs inside. One IR and the other red.

I'll try and start with 20mA. I hope it works well. If not i have another identical drive..

What really bothers me, is how easy these weak ones from the combo drives are, to take out.. In the DVD Writer, they are soldered in place, and i don't dare try to unsolder them, cos i would have to heat EVERYTHING up to a temperature, where the solder melts (the steel mounting plate and the laser diode as well). I'm afraid, this would killl it, but what i don't understand is, how they were able to solder it there, without killing it in the first place...

Reader diodes are pretty weak normally, perhaps rated 5 mW or so. For current, this usually equates to around 20 mA, but this varies among diodes. Also, these are very easily killed with too much current (they normally depend on optical feedback for power control).

but what i don't understand is, how they were able to solder it there, without killing it in the first place...

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Is it actually soldered with its case to a large hunk of metal? Usually there is a lead soldered to the diode, and the diode is mechanically mounted to the mechanism.

Benm said:

Reader diodes are pretty weak normally, perhaps rated 5 mW or so. For current, this usually equates to around 20 mA, but this varies among diodes. Also, these are very easily killed with too much current (they normally depend on optical feedback for power control).

Click to expand...

Yeah, i guessed as much.. I also think 20mA should be just right for 5mW.. I might try more since i have a couple of them. I made an arrangement with my fathers computer company's repair shop, to give me ALL the broken DVD Writers that are out of warranty.

So i already got three Writers (16x) and two combo drives and more are on the way...

I also bought a Peltier TEC element, for additionall protection during testing...

Benm said:

Is it actually soldered with its case to a large hunk of metal? Usually there is a lead soldered to the diode, and the diode is mechanically mounted to the mechanism.

Click to expand...

Yeah, the LD can in the Writers (Samsung Writemaster TS-H552 v.U) is soldered onto a steel plate, that is then screwed in place.. If you want, i can make a pic, while disassembling the next one...

On the combo drives, they're just stuck in place and can be easily removed....

Since i work with electronics and do a lot of soldering, i know that when you solder something to a larger metal piece, the ENTIRE piece of metal has to reach the temperature where the solder melts. Otherwise it won't create a bond.

If you then try to unsolder this, you have to heat the entire assembly (including the LD) to the same high temperature, and try to suck the solder away with a vacuum pump.. And you have to repeat this process a couple of times, to get ALL the solder off. And even then, some will remain, so you have to heat it up again and apply force for the LD to pop out...

I'm afraid this process would kill the LD, but what i don't understand is, how they were able to solder it there in the first place, without killing it...

For this reason, i use a dremel tool, to slowly remove as much of the solder as possible. It heats up during this as well, but you can stop and wait for it to cool down, and then continue. If instead you try to unsolder it, you can't do it in small steps..

I doubt it's steel, since that cannot be soldered... but it might be something else. Please post a picture, i'm a bit curious.

One way to mount a sensitive component onto a large hunk of metal is to heat the metal first, apply flux and solder, and then insert the component. After that, cool it rapidly by, for example, airflow. Most components can withstand 260 degrees for at least tens of seconds, so thats feasible.

The reverse of this process is difficult though, as you would need to rapidly heat the metal to 260 and then pop the component back out.

I've seen this approach in RF power transistors, but those are rarely removed unless dead already

Benm said:

I doubt it's steel, since that cannot be soldered... but it might be something else. Please post a picture, i'm a bit curious.

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You're right, it's probably nickle plated brass. I meant to say "metal". English is not my first language, so please excuse my mistakes..

The LD is then soldered onto this plate and the plate screwed in place.. I think this acts as a heatsink for the LD and since its actually soldered, the heat transfer is better than it would be by simply touching the metal and being held in place by friction, like it is on the ones that are easy to get out...

I can post a pic of how the IR LD from the same drive is soldered onto such a plate.. The red one was soldered to an even larger chunk of metal, which was then soldered some more to yet another piece of metal, with even larger blobs of solder than the ones in these pics, but i threw it away after it died.

I have another such drive, so if you want pics of that as well, i can make them, after i disassemble it...

And the other side... Sorry for the blurryness, but you can clearly see the solder blobs holding the LD onto the metal plate...

As promised, i took another pic...

I took apart the Samsung TS-H552D v. B (16x DVD+R/12x DVD-R). I decided to use this one first, since i only have one version U (16x DVD+R/16x DVD-R) left and don't want to kill it again...

It could even be they both use the same LD.. But i decided on this one, just in case..

In the pic you can see how it's soldered onto one nickel plated brass plate, that is then soldered to another one, which is then screwed into the optical assembly.. All this probbably works as a heat sink for the LD..

I made a driver circuit to protect it, and will also use a Peltier TEC this time and a lot of heatsinks.. I hope this one makes it.. Wish me luck!

Ah, that clarifies things a bit. It's not that big a chunk of metal, but probably still very difficult to remove. From what i see, i think it has been soldered in place using a powerful soldering iron, one side at a time. This can be done without heating the whole thing to melting temperature - i've done it myself with transistors onto copper.

However, removing it will be very hard, since you then have to heat both sides at once (effectively the whole thing) to melting temperature.

I think you have to get creative with the lens here.. just bolt this laser assemly onto a heatsink, aperture pointing to the side, and position the lens in front of the output. Not very convenient for a pointer, but could make a good fixed setup.

All I can say is very odd..this is the first LD I have seen soldered in.

yeah most of the time they use like hot glue or something thats easy to remove.

Benm said:

Ah, that clarifies things a bit. It's not that big a chunk of metal, but probably still very difficult to remove. From what i see, i think it has been soldered in place using a powerful soldering iron, one side at a time. This can be done without heating the whole thing to melting temperature - i've done it myself with transistors onto copper.

However, removing it will be very hard, since you then have to heat both sides at once (effectively the whole thing) to melting temperature.

I think you have to get creative with the lens here.. just bolt this laser assemly onto a heatsink, aperture pointing to the side, and position the lens in front of the output. Not very convenient for a pointer, but could make a good fixed setup.

Click to expand...

Yeah, as i said before, the ENTIRE thing would have to be heated to solder melting point.. This is a problem.. And no, it's not a HUGE chunk of metal, but it's big enough to make safe unsoldering impossible..

So i used a diamond plated cutting disc on my dremel and cut away a little at a time, so it wouldn't heat up too much from friction...

I only removed the outer plate.. I kept the inner one and glued heatsinks onto it and a lens assembly from a cheap laser pointer in front.. I'll post the results.

First succesfull test of a LD from a DVD burner

Hi guys!

I just had my FIRST successfull test of the Samsung Writemaster TS-H552 version B's laser diode (16x DVD+R / 12x DVD-R ..... i'm saving the version U for later, since i'm hoping it's stronger)

Since i don't have an AixiZ module yet, i had to improvise, using a lens from a cheap laser pointer..

I didn't unsolder the LD from the metal plate.. Instead i glued heatsinks on it..

And it worked PERFECTLY! I slowly went up to 280mA and it hardly warmed up (35 degrees celsius, measured with an IR non contact thermometer)

I finaly have a working laser!!!! It's not yet burning anything, but it has a nice visible beam..

It could probably do more than 300mA. With the peltier even more..

You can probably imagine how ecstatic i am, since before this the only results i got were dead LDs...


Thanks to everyone who helped with answers and infos!


Igor

Three things I will never forget:

My first DIY red.

My first greenie.

And my first blu-ray.

The beams from all of these is unique...simply awesome.

Congratulations..and have fun, but please be careful with your eyes... You will need goggles if you plan on burning anything.

A very promising result if you ask me!

I'm sure this laser diode is capable of burning something or lighting a match - that's just a matter of getting the focus right. Make sure that all of the light goes into the lens. If you set it up to have a focal point on the other side not too far from the laser (perhaps a foot or so), it should work fine.

280 mA sounds a bit on the high side for initial experiments to me. I don't know this diode, but it's a lot of current for a dvd writer diode in general.