Dodgy DX-30? Check the spring!

[Benm]

I recently got a DX30, which is the model with the optical assemby and end cap in once piece. It worked quite well at first, but it became irreliable after some use. I suspected the problem to be in the switch, as many people suggested here. Pressing it harder fixed the problem sometimes, so i figured that must have been it. I measured the switch with a multimeter while stil on the board, and got good results.

However, sometimes these things work differenly with some juice flowing, leaving me a bit unsure. So, i proceeded to replace the switch, but with little improvement at all. Same problem basically, and the new switch was also a bit too tall so it didnt work that practically anyways.

I measured the old switch on its own, and it seemed fine... and i soldered it back onto the board. Problem persisted like it used to. I noticed however that there is a spring on top of the circuit board that touches the casing for electrical contact. I pulled that out a bit, and used some contact cleanser ont he spring and inside of the barrel before putting it all back together.

Amazingly, that was all it seemed to have needed: it works fine again, as bright as it came out of the box, and no need to press hard to make it work at all. Aparently, you just push on the spring through the board and everything, make the switch seem more quilty than actually is.

Attached: pictures of the inside, and of the switch transplant in case anyone wants to try doing that anyway.. not very hard if you have any experience in electronics.

 

[stevetexas]

good explanation - thanks. many others have had a problem with these lasers and not much attention brought to this potential (and easily correctable) source.

 

[rizky_p]

considering the round shape of the body tube and the flat surface on the spring i would assume it wont make much of a contact no wonder being slightly dirty will decrease its performance greatly.

 

[Benm]

I think the primary problem is that the casing and spring are made of different metals - makes them corrode much more easily when under electrical load. If the problem returns, i'll probably solder a wire between the board and casing.. the outer casing itself seems made of brass and should be solderable.

On a sidenote: This problem/solution does not appy to all DX30's... i've seen pics of different circuitry found inside that is identical to the board in my DX20.

 

[Photon_Phreak]

My DX 30 mW circuitry looked nothing like that.

 

[Benm]

You probably have one with circuitry like this:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1188440672/0

For some odd reason DX shippes these 2 different lasers under the same product name/SKU, both as 'True 30 mW'. The circuit you have can also be found in (some?) DX20's.

There are minor external differences as well, the version you have is a few mm longer, and the hole in the gap is a little smaller. It's quite noticable when you have the two together, but hard to tell if you have only one.

 

[photongeek]

I recently got a DX30, which is the model with the optical assemby and end cap in once piece. It worked quite well at first, but it became irreliable after some use. I suspected the problem to be in the switch, as many people suggested here. Pressing it harder fixed the problem sometimes, so i figured that must have been it. I measured the switch with a multimeter while stil on the board, and got good results.

However, sometimes these things work differenly with some juice flowing, leaving me a bit unsure. So, i proceeded to replace the switch, but with little improvement at all. Same problem basically, and the new switch was also a bit too tall so it didnt work that practically anyways.

I measured the old switch on its own, and it seemed fine... and i soldered it back onto the board. Problem persisted like it used to. I noticed however that there is a spring on top of the circuit board that touches the casing for electrical contact. I pulled that out a bit, and used some contact cleanser ont he spring and inside of the barrel before putting it all back together.

Amazingly, that was all it seemed to have needed: it works fine again, as bright as it came out of the box, and no need to press hard to make it work at all. Aparently, you just push on the spring through the board and everything, make the switch seem more quilty than actually is.

Attached: pictures of the inside, and of the switch transplant in case anyone wants to try doing that anyway.. not very hard if you have any experience in electronics.

That's interesting Benm. Is that a "True" 30 you're referring to? My just arrived "True" is showing this same intermittent problem. How do you get these apart without destroying them? Thanks.

 

[Benm]

It's the 'true' version indeed.

How i opened it: I heated the front cap to around 60-70 degrees using my gas stove (crude but effective), and then clamped the cap in a table vise with some cloth in between to prevent damage. The body can be pulled from the cap by some twisting and rocking motions.

The problem did return after some time though, i've now removed the spring and soldered a wire between the circuit board and laser body directly.

 

[photongeek]

Ben:
Have you or anyone else done a recent IR emission test on these True 30's? I know it's been discussed before. Thanks.

 

[Benm]

I don't have any equipment to do a good IR test, so i can't comment on how much IR comes out really.

One thing i have tested is the pattern IR comes out: When running these lasers cold, or at too low a current to produce any green, you can see the dull red light from the pump when shining onto a piece of paper. I defenitely comes out to some extent, but its a wide beam, at least a couple of degrees.

It's hard to say if the pump light is blocked to some extent by a filter or the coatings on the MCA... 808 nm is so badly visible it's very hard to say anything about power levels when viewing with the naked eye.

 

[chimo]

I was a litle tired of my DX30 dimming so I tried a run that was a little over the recommended duty cycle. I ran it for 25 minutes continuous on a fresh set of NiMH. It survived with no signs of damage.

 

[Benm]

Good to know, i've had in on for several minutes with no ill effect too.

My DX20 dims with rising temperature, but the DX30 seems to reach a nice equilibrium running continously off NiMHs.

Also, i wouldn't be too concerned with doing any permanent damage, the pump diode can probably handle operating at higher temperatures for a long time. It's just the MCA efficiency that goes off with temperature variations, but returns to normal after cooling down.

 

[photongeek]

Mine works great (except for the occasional switch and/or spring contact dimming) on the E2 Lithiums but they're really too expensive. How well do these things operate on the NiMh's? You wouldn't think they would even work on less than 3 volts.

 

[chimo]

I have tried mine on a 10440 (AAA) Li-ion but that's pushing it a bit. I think that 3x 2/3AAA NiMH cells would really push it along nicely. I've seen them on-line but have not purchased any (yet).

 

[Benm]

My DX30 is fine on NiMHs, at least for a while. It dims a bit when they are close to discharge, but otherwise its very usable. This equates to about 2.5 volts needed to run at good power. Even when the cells run lower, it still puts out quite some light, but no longer sufficient to pop a balloon or similar.

Alkalines have a bit of the same story, their internal resistance rises as they discharge, so they stop providing good power before being totally depleted (which is normal i guess).

I also have a dodgy DX20 that now works reasonably well on NiMHs, but only after replacing the circuitry (see another thread here). That still dims when it runs warmer (after half a minute or so), but that problem can't be remedied by more battery voltage.

 

[photongeek]

Well, it looks like my True 30 just died It went from putting out a beautiful beam at probably close to 30mw to one that looks like a dot with the intensity of a cheap red. Maybe 1 mw? It sure didn't last long. Total estimated run time maybe 20 minutes
I guess I'll take it apart when I get a chance and see if there is anything that can be fixed but I doubt it.
Folks, pass on this model and save your bucks for a Nova!