Re boarding a DXtrue 100

[tomcat]

i have decided to remount my dx into a cheap lab laser (mounted in a old cpu block) but i really want to redriver it so anyone know the specs i will need to drive the 808 (ma / v) for this module with analouge or ttl 10-20k

i have potmodded this driver atm and it seems to hang in just fine it just makes a touch more heat

also does anyone have any broken dx trues (anything but the lens broken) because it needs a new lens because clumsy git here managed to scratch it when focusing it

heres the bit i need

or just send me the whole thing

yes this is the one i was thinking of selling now its going in my first scanner or i could put it back together after lens fix and sell ( works just fine dont worry iv done it about 9 times now and wont sell without good lens and i will clock it back down with the pot if your worried about breaks)

ps the purple thing is damage to phone camera by said laser

 

[IgorT]

I'm also currently working on my DX200 but i took it appart completelly, to make everything adjustable.

Unfortunatelly, adjusting the crystals with the pump diode is a pain, since it's not collimated at all.. I wouldn't recommend trying. Currently, i'm trying to put a tiny collimator in between, to get more light into the crystals.


You don't need that entire bit for the lens. The lens can be taken out of there.. And BTW, Aixiz lense holders fit in there as well, but they have a different power, so you would also need to adjust the expander lense above the crystals.. To bad that one is held in place by blobs of glue.. There's glue everywhere, and i spent a lot of time cleaning it out. Just don't touch the crystals or the IR LD nut!


Figuring out the current for the LD should be very easy.. Take two full batteries, that you usually use, connect them to the board through a multimeter, and turn the laser on.. The current you see going into the driver is the current going through the LD. It is possible, that the current through the LD is slightly higher tho, as i noticed, that measuring it this way, interferes with results.. I have to put my DMM in the 20A range, to get the best results, and the current shows up much higher than in the 2A range..


After that, you just configure the LM317 to give out that exact current. Even better, start a bit lower, observe the results, and work up. (not with a pot!)..


If i manage to fix mine, i'm also going to replace the driver, and then use two AAA size Li-Pos (10440), to power it in the same housing.


BTW, did yours have any mode hopping problems? Oh, and does turning the pot actually achieve something in these?

 

[pwnstar]

eh i might want to do this myself... im pritty sure i burnt out the crystal on my DX200
im only getting about 5mw of green out of it now and a hell of alot of ir...

 

[IgorT]

eh i might want to do this myself... im pritty sure i burnt out the crystal on my DX200
im only getting about 5mw of green out of it now and a hell of alot of ir...

What happened to it? Did you drop it? I don't think you burnt out the crystals.. It's MUCH more likely, that you just slightly dislodged the pump diode, since every time you push the button, you also push on the PCB, that is only supported by the legs of the IR LD.

I could actually change modes by varying the pressure on the button.. Just imagine, how much stress that puts on the poor LD, every time you turn it on.. In one case, the PCB got so bent, that the spring shorted to the housing..

This is a major design flaw, if you ask me.. When i just put a piece of plastic underneath the PCB, to support it, the laser immediatelly became way more stable..


But i thought it would get even better, if i tightened the LD. Unfortunatelly, everything went wrong after i did that.. Before it was just mode hopping, after, it lost most of it's brightness..


It took me an evening, to take it all appart and clean out all the glue residue. After that, it took me a week, to figure out, how the crystals are supposed to be positioned in relation to the pump diode.. I'm still not back at full brightness, but i got rid of mode hopping finally.


I had to make a special tool, to adjust the crystals with the laser on. I wouldn't recommend doing this to anyone. But in your case, if you're only getting 5mW, it can only get better..

It's easy, to get half of the brightness back. But the second half is about fractions of milimeters, and PERFECT alignment with the LD. Whenever you turn the crystals, you have to turn the LD accordingly.


Just now i discovered, that diagonally is the best alignment.. I just need to get it a little bit closer together.. But i did just manage to light a match again!

 

[pwnstar]

hmm well i was using it on a very cold night and i saw it was getting dimmer very fast.
i thought it was just the batteries going out on me. but the next morning it was goin from gran to i tiny bit of red and then off. i shook it around now its about 5mw green continuously.

your right i will probably open it up and try to realign the crystal

how do i go about opening the top of the laser?
what is probably the cleanest way to open it?

 

[IgorT]

your right i will probably open it up and try to realign the crystal

how do i go about opening the top of the laser?
what is probably the cleanest way to open it?

Realigning the crystal will be VERY hard. But i'm doing the same thing, so we can share our experiences..

But i would suggest you do something else first.. Open the battery compartment, and look into the head, at the spring.. I'm guessing, it is bent very far down, in the direction of button pressure. Take the foam out and try bending the PCB up just a little bit, and put something under it (under the big power transistor) to support it. Then test the laser.

It could actualy solve your problem. If it doesn't, bend the PCB a little further up, and support it again. Only if nothing changes, should you take it appart..


Taking it appart is hard as well. The head is stuck in there good. I damaged the paint, when pulling it out. People have had most luck, by squeezing the head in a vice, between two blocks of wood and/or applying some heat to the head, and then force..

There is one thing you should NOT do in ANY case - do not turn the head around, as if you were unscrewing it. If you do, you will rip out the legs of the pump diode.


You have to mount the head somehow, and then slowly edge it out, by pulling and pushing it forward and backwards, while also pulling it out.



When it's appart, you will find LOTS of glue everywhere. The collimator lens is glued into the upper brass piece, but you can leave it there.. The expander lense is probably held up by only four blobs of glue, above the crystals..


It might be best to leave this lense and the crystals glued in place at least in the beginning, and only try to realign the pump diode. You have to unsolder the PCB, to get access to the diode nut.. The nut is also glued in place, so you'll need a bigg flat head screw driver, put it in between the LD's legs, and try to break the bond.. Be carefull that the screwdriver doesn't loose grip, and breaks one of the legs, it will be in between.

Once you break this bond, you will have to use something sharp to clean the glue residue out of the module and the nut threads..

Oh, and be carefull with the IR LD. It has no can, and the laser chip is very exposed.. There are three hair thin wires going to it, that could get damaged.


After that, you have to mark the diagonals of the crystal on the underside of the module, and try to align the laser chip with one of them. It shouldn't be too hard to get a big increase in brightness, by simply rotating the diode a little bit... You probably won't get to 100mW, but it should get bright.


Only if this doesn't help, should you remove the expander lense (you will have to mount it back later, or you won't be able to collimate the beam). After that, you have to break the glue, that holds the crystals in place, without breaking or scratching the crystals themselves..

I made a special tool for turning the crystals from the outside, with the laser on. I'll make a pic of it tomorrow.


Good luck! And be very carefull, not to touch or scratch anything sensitive.

And please don't look at the IR or it's invisible reflection.. It makes a small red spot, but on a camera, you see a HUGE flood of light on the table, even through an IR filter.

 

[pwnstar]

hm ok ye i have a piece of plastic under the pbc already
it seems very stable so im not sure what else i can do there.

ok tommorow ill try going about opening the front of the pointer
thanks alot for that writeup^^^

if aligning the crystals is very hard could this just be used as a very powerful IR laser?
i kno this may sound like a noob question but im looking for my options

 

[pwnstar]

and what is in that piece that tomcat needs?

 

[trueHOUSE]

im trying to do the same with my dx 50 its verry hard to adjust the crystals i have almost the same power now but the beam  is looking like when you look at a star and i have the dimming problem. Irealized that the dimming problem comes because of the button when i turn it on and move my finger on the button it gets at full power . it took me 2 days to realign the crysta set . do you know how to fix the dimming ? if its not from the button as i think ?

 

[IgorT]

Irealized that the dimming problem comes because of the button when i turn it on and move my finger on the button it gets at full power . it took me 2 days to realign the crysta set . do you know how to fix the dimming ? if its not from the button as i think ?

You can not be sure, it is not from the button, unless you have the "driver" supported from below.
Otherwise, when you push the button, you put stress on the LD's leads. Whoever designed this is an idiot!

But luckily, simply supporting it, by sticking a piece of plastic under the big power transistor, on the opposite side of the PCB from the button, can help A LOT.


On the other hand, from what i've seen with mine, this dimming immediatelly after power on, does actually come from a bad alignment.. It would start very bright, then immediatelly dim down, and stay on a lower level of brightness.


I'm surprised, you managed to get it back to it's original brightness.. Are you sure it is on full? If it is only on "full", before it dim's, it is not back yet, i'm sorry to say...


As i said, aligning the crystals is VERY hard, and there is only one perfect combination of positions of both the crystal nut and the pump diode:

- The crystals have to be as close as possible to the diode, without touching the laser chip, since it's an open can.

- Also, the laser chip's wide axis has to be aligned with one of the crystal's diagonals.. Then you have to make very small adjustments around this position, with the laser on. And i mean VERY small.

For this you need a special tool, which allows you to turn them from the outside, while pointing it away from yourself.. It also holds them in place, once you're done, so that you can glue them in place.


I made this tool, by cutting it from a piece of alluminum, and bending it. I'll post some pics.

Before i figured out the diagonal alignment, i had very bad results.. Now i finall narrowed the unlimited combinations, down to four.


Since i don't have a fast axis lens, i was thinking, what would happen, if i exposed the crystals to the wider axis diagonally, so that more light would hit them. And it helped incredibly! Before, it was all guesswork, and luck, if i hit anything at all, now i can get reliable results, without dimming after power on.

 

[IgorT]

and what is in that piece that tomcat needs?

That piece between the top and the laser module only contains the collimating lens. It also provides the laser module a path for heat.. You have to take it off, during alignment, so the duty cycle has to be very short..

If you only have this piece on the module, you can see a lot of IR coming out along with the green.

But with the top on as well, the amount of IR decreases a lot, simply because of the narrowness of the hole. It decreases so much, that it is not visible next to the green on a camera,

hm ok ye i have a piece of plastic under the pbc already
it seems very stable so im not sure what else i can do there.

When did you support it? Did you also notice changes in behaviour from button pressure?

In this case, it is very likelly, that your diode only got slightly dislodged.. Mark it's position as exactly as possible, unscrew the nut, and try very small changes (rotation) around the marked position.

ok tommorow ill try going about opening the front of the pointer
thanks alot for that writeup^^^

No problem.. As i said, i'm working on pretty much the same thing right now, so i know how hard it is.. I was bugging BluePhoton with questions for a few days now, and he helped a lot.

I would never figure out the diagonal alignment, if he wasn't insisting on a fast axis lense..

if aligning the crystals is very hard could this just be used as a very powerful IR laser?
i kno this may sound like a noob question but im looking for my options

That would be very easy... But VERY dangerous!

If you do not have IR glasses, do not even think about it.


I tried it on a floppy disk, while observing the results through a camera. When the spot looks very small, there is a huge flood of light on the table..

You can not focus it, without IR protective glasses and a camera at all. And even unfocused it was smoking the floppy on contact.

 

[IgorT]

TomCat:

You don't need the original lens.. If you move the expander lense, so that the beam is expanded more, you can use an AixiZ lens, and you will have better focus adjustment..

You just need to get the nut with the scratched lens out of the brass piece your finger is pointing at..


I noticed, if the beam is not expanded enough, trying to collimate it doesn't work after a certain point. You simply can't make the dot smaller.


If you expand the beam more first, then an AixiZ lens would work perfectly, since it is more powerfull, than the original. Not to mention higher quality..

The black plastic AixiZ lens holder also fits into those threads perfectly, once you clean the glue out of them.


I have some brass dust on mine, and it looks like it doesn't want to get off. So i'll be replacing it too.

 

[trueHOUSE]

I'm surprised, you managed to get it back to it's original brightness.. Are you sure it is on full? If it is only on "full", before it dim's, it is not back yet, i'm sorry to say...

yes as i told , its on full brightness (original) but there comes the dimming :-[ so you say thats from the alignment ? ill try to realign it maybe

 

[trueHOUSE]

to realign it just dont have to remove the original glue thats the only way to get it to its original place for 1 minute or less thats the mistake i made i removed the sticked glue

 

[IgorT]

I'm surprised, you managed to get it back to it's original brightness.. Are you sure it is on full? If it is only on "full", before it dim's, it is not back yet, i'm sorry to say...

yes as i told , its on full brightness (original) but there comes the dimming  :-[ so you say thats from the alignment ? ill try to realign it maybe

I'm pretty sure, this is the same thing, that i observed, when i didn't align the crystals perfectly with the pump diode. It comes on bright, but immediatelly dims to a much lower brightness and stays there..

It's not enough to just turn the crystals and change the distance. You have to align the IR chip with a one of the crystal's diagonals, because that is the fast axis, where light spreads much more.

The more light you get into the crystal, the better. This is why a diagonal alignment is very important here, since the IR is not collimated at all.


It also means, the closer you get the crystals, the better. Unfortunatelly, it is very easy to kill the pump diode, by screwing the crystal assembly into it.

I did this:
- First i brought the crystals as close as possible, without them touching the diode, and marked their diagonals on the module.
- Then i loosen the diode, and align the chip with one of the pair of markings and tighten the diode back in place.
- Then i put the crystals back in and carefully screw them in till they are as close to the diode as possible.
- After that, i just hold the module under a light, because i can actually see the laser chip through the crystals this way.
- By seeing the laser chip, i can turn the crystals a bit, so the wide axis is aligned with the crystal's diagonal perfectly.

After this, i just test the power.. At this point, there are only four possible positions to test for power.

Oh, and ALWAYS unscrew the crystals for a couple of turns BEFORE turning the diode.. If it touches them while turning, it could get destroyed permanently..

to realign it just dont have to remove the original glue  thats the only way to get it to its original place for 1 minute or less thats the mistake i made i removed the sticked  glue

I don't understand what you're trying to say..

In my laser, i marked the original position, but it turned out to be completelly useless. If i want constant power, without dimming, i have to bring the crystals much closer.

 

[pwnstar]

TomCat:

You don't need the original lens.. If you move the expander lense, so that the beam is expanded more, you can use an AixiZ lens, and you will have better focus adjustment..

yea replaceing that lens with a glass aixiz lens sounds like a really good idea.
i will also probably be adding a ir filter while im in there...

these are good to read
http://www.laserpointerforums.com/forums/YaBB.pl?num=1205187456
and
http://www.repairfaq.org/sam/laserpic/glpdpics.htm