Other diodes in LG 8x Sled

I'm trying an experiment with the other diode I found in the 8x LG blu-ray sled, it has three pins horizontally and an incredibly small optic window, I'd guess it's about 3mm and I was foolish enough to power it on at 5ma at 4v and pointing it at a dark surface it produced a red dot that immediately gave me a headache (I know it was stupid to not wear my goggles):tsk: So before I do any further tests on this, I need someone who knows to tell me if I'm playing with the IR or the DVD burner diode? I can't imagine why it was so bright at 5ma (I'm using a digital bench power supply so I know what the dc output was)

lv128;

At 4 VDC ...
you were putting a lot more than 5 ma thru that diode.

3 VDC is usually full output on a Red laser diode from a 16X burner.

Recheck your current again.

Was it a flat plastic diode about 1.3mm thick ??

LarryDFW

Hehe, did the PSU say 0.5? :angel:

That would explain the headache.... :evil:
Otherwise, my PSU, while it has current limiting, only shows down to 10mA resolution...
But yours could have a display with more digits, i made mine myself..


However at 4V (and if you had any current limiting engaged), there had to be AT LEAST 500mA flowing through the diode!


But then again, i have two of them here, and can test them...

Well, I had it programmed for testing a bluray diode and had it setup to 400ma, the display is in whole amps, but it shows .005A which unless it's displaying it strange should be 5ma, but I've only had this (chinese made) unit for about 2 days, so not sure. yeah in any case, it died almost instantly. So here's to learning :beer: It wasn't a great loss anyway.

Larry, yes it was as you described. I had no idea the dvd burner cans were so small!
I was expecting another 5.6mm can. I'm curious where the IR diode for CDs are and/or if I missed it while harvesting the sled.

lv128 said:

Well, I had it programmed for testing a bluray diode and had it setup to 400ma, the display is in whole amps, but it shows .005A which unless it's displaying it strange should be 5ma, but I've only had this (chinese made) unit for about 2 days, so not sure. yeah in any case, it died almost instantly. So here's to learning :beer: It wasn't a great loss anyway.

Larry, yes it was as you described. I had no idea the dvd burner cans were so small!
I was expecting another 5.6mm can. I'm curious where the IR diode for CDs are and/or if I missed it while harvesting the sled.

Click to expand...

Before we had 405nm diodes, i bought many a 22x drive in search of open cans. Unfortunatelly i often found a flat black thing, looking exactly like the one in the LG 8x..

They can produce a lot of power, but mounting them is another story...


If your display was showing .005A then it really was 5mA, however i don't understand why. Did you have any kind of current limiting engaged?

Even so, at 4V the PSU would engage the current limit with a delay, so the initial spike would kill the diode.

If there was no current limiting, maybe it fried it so badly, that more than 5mA couldn't flow through it? Altho i never ever saw such a thing.. :thinking:

If you're saying that your eyes were hurting and you got a headache WHILE your PSU was showing .005, then there is something wrong. Because a diode like that won't do a thing at 5mA. Their threshold current is like 80-90mA!



I once wanted to kill an open can that was wedged in an AixiZ module at an angle, but i didn't just want to hammer it out.

So instead i soldered a 47uF tantalum across it's pins, and two wires, put it in a giant heatsink mounted in a vice for even more heatsinking, and set my PSU's current limit to 0.6A, and then slowly raised the voltage from 2 to >3V, until i saw the current limit engage (a red LED turns ON on mine when this happens)...

Well, that diode surprised me big time, when it took almost exactly 24h for it to become a 5mW diode!


Otherwise, a small warning, about powering diodes (which is not a good idea anyhow) or lasers directly from a PSU...

Even if there is a driver with protection caps and all between the diode and the PSU, if you have any static charge on your body, and touch the laser or module, while it is connected to the PSU, there is a big chance you'll damage the diode.

I use my PSU to test drivers, but for powering lasers, almost exclusivelly battery power, because then, ESD has nowhere to jump - no ground path...

I just removed the red diode from another BDR 203 and set it for 2.2V at 100ma, the power that came out of it was phenomenal. I don't know what the max would be and I don't want to kill this one, but I did remove the heatsinc off it completely, what it appears to be is almost like a C mount without the hole in the center. So now I think sightfx had a solution for mounting these, something he machined out of copper, I have a PM into him to see if that is indeed what that's for.

I hooked up one of those flat ones from a lg 8x directly to a 3.7v CR2 and it put out about 150-160mw of red. i modified an aixiz and mounted it in there with a aixiz glass. it now serves as the red behind one of my spiro's.

The modules I make are for the 3.8mm can type diodes that are in the BDR 203s I think that c mount looking diode is IR. I've treated the 3.8mm can is if it were a LOC diode and it worked great but no data on those yet so no way to tell how long they will last at the same current. Sitting in a 3.6mm copper press fitting will at least conduct the heat away pretty good and it kept it from getting to hot too fast.


Thanks,

Ryan

You guys are making me wonder if that plastic c mount looking thing is in fact Red and not IR. I know the 3.8mm can in those drive are Red but would they have 2 in there for some reason?


-Ryan

In my case, I've been using LG sleds and claiming they're "BDR203" cause I got it mixed up in my head where "BDR" was blue ray disc? (don't ask) but either way, I've only ever dismantled 8x LG drives and the red/IR diode is indeed flat. it has no photo sensor, so the center is common - the right (as looking from the back) is IR + and the left is LD+

"It's so tiny, I had craps bigger than him!"

Ah ok,

I have my first 8x LG so I will harvest that diode and see what I can do to make a heat sinking aixiz type adapter for it. Maybe some sort of clamb shell with a colar to hold it pressed to the package or something like that.


Thanks,

Ryan

lv128 said:

what it appears to be is almost like a C mount without the hole in the center.

Click to expand...

Wait... These flat diodes put out light in the same axis as their length..

C-Mounts put out light in the same axis as the screw that goes into that hole they have in the middle, intended for tightening to a heatsink...

Why did the flat diode remind you of a c-mount? Or is it different from the ones i've seen before?

Well not from a scientific (axis) viewpoint, but they remind me of c-mount since the lasing diode is not protected at all via a can or lens, they simply lay on top of a metal plate similar to C mount. although unlike c mount, they have pins for each anode and cathode, where most c-mount the entire mount is the cathode. they do have a heatsinc, although it fell off on mine leaving the exposed diode. what I found particularly interesting is that in testing, I was able to get it to lase at up to 3.1v at 325ma, and it consumed approx 1W of power without failing, but then I pumped it up to 400ma and it lased for a second then went dim, I thought I had killed it but reducing it back to 325 it was bright as ever. Also I noted with a non contact thermometer is produced almost no heat and also seemed unable to burn no mater how it was collimated. I wish I had an LP meter or better testing tools