Hi people, a couple of weeks back I decided to do a list of dvd burners that are good for getting the diode out and in what type of format closed can/open can and the dreaded fully open hunk of metal ( for want of better words) after looking around a few sites I came across a diode that appeared to be getting good reviews from a few people so I decided to see what all the fuss was about, the dvd burner in question was the pioneer 112 this was nearly two weeks ago, two days later the two units I bought arrived costing around £46 for the pair. Having spent two weeks tomorrow testing them I am very pleased with them, I initially bought two one for keeping and the other to test to destruction but after 2weeks of well over the top running conditions I did not have the balls to kill the little guy and he is still running as good as the first day he started spitting out coherent light, if I damaged the diode or not is a different matter but at the moment there is know visible signs of degrading whatsoever.
This is what I done with the diode, after getting the main optical block of off the the guide rails inside the burner case (this was easy just a few screws to undo)as in picture 2 this is with the cover taken off.
The removal of the diode was pretty much straight forward leaving the diode in a heavy for its size heat block as in picture 3
I clamped the heat block in the vice and made a small cut on the thickest part of the heat block ( be careful not to go to deep ) then got two pairs of grips and carefully broke the heat block leaving just the diodes the heat block almost felt like lead it certainly cut like lead with my junior hacksaw (im guessing here) cut it like picture 4
At the end of it you should be left with a diode or diodes like this in picture 5
After wiring it up and covering the wires with small heat shrink tubing I inserted the diode into a piece of 12mm aluminium bar that I had already machined with the correct counter bore(5.6mm) as in picture 6
Picture 7 shows the diode mounted on the 12mm aluminium bar with thermal epoxy resin on the top and behind the diode this stuff excels in thermal dissipation and it goes off rock hard just make sure your happy with the position before this stuff goes off as you never be able to move it once it has dried off which depending on the heat in the area can be 5 minutes to 15 minutes totally rock hard after a few hours
Picture 8 shows the 12mm round bar inserted into the main heat sink block which I had machined earlier on in the day the optic part most of you will recognise as the axim laser module I only use the front optic part, the 12mm bar and the optics are held in place by 3mm grub screws they are a bit long but I ran out of the shorter type the brightness of the laser has over saturated the red that’s why it looks more white than red, also the 12mm bar has a normal thermal compound on it to suck the heat into the main block
The test, which is still ongoing, is a long term stability test which started almost 1.5 weeks ago normally with a 16x/18x or 20x diode I would see what other people are cranking there’s up to and keep mine around about the same all depending if you want high power for a shorter diode life and visa versa but after reading a couple of reviews I decided that the diode that I thought I was going to test to destruction was going to get high power from the off so I cranked it up to 180mw for the first couple of days just checking the power from time to time and beam shape all looked well so the next couple of days it went up to 200mw where it sat for 3 days this is the nice part I then took the poor little thing up to 250mw where it still sits today from 180mw the main block was 2 degrees over room temperature at 250mw it is 7 degrees above room temperature( 21 degrees room temp ) 28 degrees in total the most striking differnce between this laser diode and others that I have used is the size of the laser chip itself measuring approximately 30% longer than other chips I have seen there could be lots of reasons why this is the most common is laser gain and dopent levels either way it makes one hell of a diode you can see the difference in size on picture 9 the diode on the right is a Lite-On LH-20A1p 20x burner the pic on the left is the PIONEER 112 you can clearly see the difference in length.
To get 250mw I am using one of Robin’s driver boards ( great bits of kit) at 3 volts at 339 milliamps now I am thinking of combing two for half a watt of red, I don’t know how much longer it can take this sort of punishment bUt rest assured when it goes to diode heaven you guys will be the first to know but in the mean time I shall just have to put up with the wife moaning about turning it off
All the best Paul.
just a caution try this in a axim module and you will probably fry the diode in 20 minutes.