Violet laser assembly info & VIOLET pointer building info.
heruursciences
parts, but an aftermarket part. I tried one in place of the original
in a PS3 and it plays music CD's ok, DVD games OK, and when I put a
blue ray game in it had a little trouble loading it though it did load
eventually. Either there is some special adjustment that needs to be
tweeked or that the violet laser is barely stable enough to be used
for disk reading. The part number is also slightly diferent The OEM
part is KES-400AAA, the parts on ebay are KEM-400AAA.
The mechanics of the thing are a work of art, it was almost a shame to
rip the diode out. After a brief shrug I deftly removed the diode with
a small phillips screwdriver and scissors. Then i removed the diode
from it's heat sink by gently bending the heat sink, the diode pops
loose very easily and was cleaned with an exacto knife and a q-tip
with acetone.
To test the diode i used a SMD soldering pencil and fine eutetric
63/37 solder to solder wires to it. The solder used by the OEM to
solder the diode in is indium bearing low temp solder BTW.
The diode drops about 4.3V at low current, and 4.5V at operating
current, it threasholded at about 26ma and at 40ma measures about 10
mW. The output is much more multimode than a typical dvd or cd read
diode, and even most laser pointers! No wonder it could barely read
the disc!
Now the fun part! The challenge was to build a violet beam laser
pointer that can run off a single battery!!
First the diode was de-soldered from it's polyimide piece using a very
hot iorn and very fast, it desolders quickly with a 40W soldering
pencil in less than a second. It was then put into the colimator
assembly from a cheap laser pointer (make sure it has adjustable
focus capability) powered and adjusted to collimation.
Then I went to sporting goods stores and bought 1 each of all the
single battery white led flashlights i could find in town in hopes to
find one with an inverter that is not potted. The winner was a $5
chinamatic one made by dorcy company. The next step was to find out
how the driver is working. It is a 2 transistor osscilator with a
small choke with the LED across it. It uses the inductive kickback to
generate the higher voltage the LED needs, but how high?
I measuered it with an O-scope and the kick was over 50V peak!!!! E-
gads much, much, MUCH too high, translated into current that is pulses
in the multiple AMP range going to the LED! Guaranteed instant death
for ANY laser diodes!
The next thing to do was simulate the laser diode using the white LED
and get the pulses to a reasonable level. The first thing is to
isolate the pulses using a signal diode and add some cap to buffer it.
It so turns out a 0.1uF MMC bypass cap (small size SMD brownish things
on motherboards by the dozens) drops the voltage to a more sane 6.4V
peak with a more sine type waveform with the LED load, Then a 5.1V
zener diode is put across the cap, giving a relitively stable 5.1V
across the LED
Next is the part where you use a real laser diode, since laser diodes
are current sensitive the current must be limited by a resistor. I
used a 25 ohm reostat to adjust the current to lase the red DVD diode
in the device at about 35ma for 24 hours to be sure the device works
fine and won't kill it. There was no noticible change in power of the
DVD diode.
Now for the scary part, I decided to set the current peak to 40mA, and
used 15 ohms of resistance in series with the VIOLET laser diode. It
WORKS!!! A PURPLE BEAM single AAA laser pointer at 7.5mW of power
average current to the diode is about 38mA . I finished it by potting
it in the original flashlight case with 2 ton epoxy
I only wish the color was a few nm longer in wavelength as i can's see
it that well, in fact the IR laser diode in the thing at 6mW appears
at least half as bright as the violet laser to my eyes. As a whole
it's about the same brightness as a radioshack first generation 1 mW
670nm pointer. If you're planning to build one of these a sensitive
thermopile powermeter is ABSOLUTELY REQUIRED for the sake of the
diode!
Anyway I'll probably make a couple more of them and list them for sale
on ebay.
Mike Harrison
>Got the PS3 assemblies in, it appears they are NOT genuine sony oem
>parts, but an aftermarket part. I tried one in place of the original
>in a PS3 and it plays music CD's ok, DVD games OK, and when I put a
>blue ray game in it had a little trouble loading it though it did load
>eventually. Either there is some special adjustment that needs to be
>tweeked or that the violet laser is barely stable enough to be used
>for disk reading. The part number is also slightly diferent The OEM
>part is KES-400AAA, the parts on ebay are KEM-400AAA.
My guesses are :
Rejects that failed test
Production items that have come out the back door of the factory,
Sony have superceded the design and these are stock of the older version.
Over-production built due to pessimistic forecasts of failure rates
A common assembly developed for both Sony and others, and they were actually intended for someone
else's Blu-ray player, and maybe that company folded.
I can't believe any third party could attempt to make something this exotic - the engineering
investment in something like this must be collosal - well into millions surely.
They have to have come from the original manufacturer ( which is probably not Sony) somehow.
Lostgallifreyan
news:1174676995.8...@n76g2000hsh.googlegroups.com:
> The solder used by the OEM to
> solder the diode in is indium bearing low temp solder BTW.
Nice. Figured it would be, those leads are entirely too short for anything
high.
Nice report too.
Lostgallifreyan
> The mechanics of the thing are a work of art, it was almost a shame to
> rip the diode out. After a brief shrug I deftly removed the diode with
> a small phillips screwdriver and scissors. Then i removed the diode
> from it's heat sink by gently bending the heat sink, the diode pops
> loose very easily and was cleaned with an exacto knife and a q-tip
> with acetone.
>
.
.
.
> First the diode was de-soldered from it's polyimide piece using a very
> hot iorn and very fast, it desolders quickly with a 40W soldering
> pencil in less than a second. It was then put into the colimator
> assembly from a cheap laser pointer (make sure it has adjustable
> focus capability) powered and adjusted to collimation.
>
Got to say though, this confuzzles me to no end... It looks like two very
different descriptions of the way the actual LD is mounted.
heruursciences
something that resembles torr-seal to the metal heatsink. It pops off
easily if you bend the heatsink slightly with pliers. I de-soldered
the diode so i could press fit it in a laser pointer lens assembly
without fear of breaking the leads attaching the diodes internally.
On Mar 23, 2:33 pm, Lostgallifreyan <no-...@nowhere.net> wrote:
James Sweet
>
> Then I went to sporting goods stores and bought 1 each of all the
> single battery white led flashlights i could find in town in hopes to
> find one with an inverter that is not potted. The winner was a $5
> chinamatic one made by dorcy company. The next step was to find out
> how the driver is working. It is a 2 transistor osscilator with a
> small choke with the LED across it. It uses the inductive kickback to
> generate the higher voltage the LED needs, but how high?
>
>
Several companies offer assortments of white LED boost converter chips.
Check out National Semiconductor, might be easier than hacking
flashlights and they have all the datasheets and app notes.
Lostgallifreyan
news:1174708208.2...@n59g2000hsh.googlegroups.com:
> Basically it's soldered onto a polyimide flex circuit and glued with
> something that resembles torr-seal to the metal heatsink. It pops off
> easily if you bend the heatsink slightly with pliers. I de-soldered
> the diode so i could press fit it in a laser pointer lens assembly
> without fear of breaking the leads attaching the diodes internally.
>
Ok, thanks, that's what I'd thought, and hoped. Just wanted to rule out the
possible use of low-temp solder on the case too. (Which is actually how I
might mount one, amongst other options, any existing solder would have to
be understood before applying new).