MB-Sub X1-VB focusable back-up - pictures (heavy)

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Walterk

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There are things I would like to know. And if I can't find the answers, I start looking for them, so to see how this light works I ended up buying one second handed. To help others interested I post here some findings.
Any pawning occuring in this report is undeliberate.

The X1-VB is a focusable dive-light made by MB-Sub, 3x AA with Cree XR-E. The lamp is mainly used for back-up light and signalling.
The same mechanical parts are used for the VB-50, as focusable canister divelight lamphead with a SST-50 led.
The maching and build quality is impressive. The mechanism is ingenious, simpe and not simple at the same time, ausgezeichnetes plan.
The fresnel lens is plastic, 2mm thick, the glass front lens is 6,5mm thick.

For maintenance you can and you should open the light now and then to clean from sand and check lubrication. The front bezel can be gently pulled to free the focusing assembly from the lamp. Two o-rings are to prevent water ingress, the third o-ring locks inside a groove, to prevent the focusing assmebly to fall out from the lamp.

By turning the ring on the front, the beam width changes. You can keep turning in any direction until you drop, changing the beam endlessly from narrow to wide and from wide to narrow etc.

The focusing system consist of a cylindrical slide that travels between lens and led.
The slide moves in axial direction, as it is the only way it is free to go. Its fixated in radial movement by two sliding rods that give guidance but prevent the slide to turn with the front bezel.
The slide has a curved groove on the full perimeter. It’s a faint curve with flat ends to keep friction low. By turning the front bezel, one set screw protruding this bezel on the inner side, pulls on the slide from the inside of the groove. The slide has no where to go; it can't turn because of the guide rods, it only can give in and follow the cam. And so it does.

The pictures:
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03-MB-Sub-X1-VBNext-Size-17 by wk_cpf, on Flickr

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DIWdiver

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Great pics! You must have a nice camera to get that good a picture of the FET. Mine always come out blurry at that size.

Looks like it's direct drive. That actually limits your options unless you add a driver. If you put 1S3P LiIon pack in there you'll probably fry the LED. The alkalines have enough resistance to limit the current to a safe level. But they would never drive an SST-50 anywhere near full power...

If you want to swap out the FET for something known and need help, let me know and I can help you find a good part.
 

Packhorse

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The use of the freznel lens is interesting.

When focused in a tight beam what is the distance between the lens and the LED?
How wide is the freznel?
 

jspeybro

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Thanks for sharing!
Can you give the height of the plastic part on the right in picture 28?
 
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jspeybro

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The use of the freznel lens is interesting.

When focused in a tight beam what is the distance between the lens and the LED?
How wide is the freznel?

i read somewhere else it was about 45mm in diameter.
I have used a 50mm fresnel lens in a greenforce pro head with a xml, works very well but I had to put the driver between the led and the lens due to space restrictions. this is not an issue though.
 

Walterk

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@DIW-Diver; I've used used my Samsung EX1 F1.8, the end of daylight, tripod and a 500W halogen. Black and shiny...but fun practice.

Maybe its 750mA due to resistance..? Haven't measured.
It is exactly same brightness as Tank 737 18650 aspheric, for reference. And that one I've measured 20 kcd so 17.5 seems conservative (AA vs NimH?).
There is less stray and cleaner spot then most aspheric lenses I have. Maybe the plastic filters the weak stray light.
Again compared to the Tank737 the spot size was about 30-40% of Tank's projection.
So there is something to say about fresnel.

Appreciate your offer! Am struggling with electronics but see use for several projects on hands but no actual need for the moment.


@Packhorse; The focal length is about 18mm plus 16 (estimated) travel makes 32mm, top of star (underside ceramic base led) to back of lens (+0.5/-0.5), and the clear opening of the tube and thus effective window of lens is 27mm.

@Lucca; Its a smart lamp. Maybe the older leds have higher Vf and Eneloops became standard practice. Refining concepts is a good thing. Thanx again for the Fet analysis.

@jspeybro; Thx and YW. The length of the turning bezel is 20mm, but fully out there is very little play to the front lens.
Why do you ask, thinking of lathing a Ledlenser Tir or Ahortons aspheric ;) ?

Would be usefull to raise amp a bit to stand its competitioners.
It fits 7xAAA, not 4xAA, but would fit 32600 (3500mAh) / D-size depth available, and quite some heigth for driver, the bore is 32,5mm. Maybe make batteryholder with build-in current limiter.
 
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jspeybro

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@jspeybro; Thx and YW. The length of the turning bezel is 20mm, but fully out there is very little play to the front lens.
Why do you ask, thinking of lathing a Ledlenser Tir or Ahortons aspheric ;) ?
I ask because it will most likely give a better idea of the focal length of the lens. 20mm seems a more realistic number compared to the 27mm clear aperture. I'm guessing the lens itself will be 30mm diameter?
I currently have 50mm lenses with a a reasonable short focal length, works perfect for maglites and some MR16 greenforce heads, but I'm looking for something slightly smaller with a shorter focal length in the range of 18mm. The fresnel lens used in this light seems almost perfect.

No, I'm not lathing tir's or ahorton aspherics, I'm a fan of fresnel lenses due to its short focal lengths compared to its thickness (at least for some of them).
 

DIWdiver

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Would be usefull to raise amp a bit to stand its competitioners.
It fits 7xAAA, not 4xAA, but would fit 32600 (3500mAh) / D-size depth available, and quite some heigth for driver, the bore is 32,5mm. Maybe make batteryholder with build-in current limiter.

I could mod an IS1006 to lower current and lower dropout. It would be a good match for an XM-L and that 32600.
 

Walterk

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@jspeybro; The fresnel must have been cut to size, as the rings are slight off-centered while the lens is in the middle of the sliding bezel.
In my reply to Horsepack I've made corrections in stating the focal length, forgot earlier to add the length of travel from the sliding bezel.

From Ra's postings I understood increasing effective window in anny way does alter F-number.
But I suspect lumen-drop-off from short focal length is way less with fresnel due to the ridges?
Nay... the ridges are on the outward side of the lens. So you would still have reflection losses on the led side of the lens...

@DIW-diver; The available space for PCB is 25,6mm, available height 12mm.
Problem is some M4 threaded battery contact needs to be placed in the center, also to protect the driver from being crushed, and the reed needs to stay in its position.
The wires pass through the back, so the PCB would have to be made to match. Well, I don't practise diving, all I do is snorkling anyway :)


Edit:
I have noticed this light has a very high self drain when not in use. Within 3 weeks the output is hardly visible. Just load it before diving and store it without cells.

Thinking of keeping the XR-E, and modding it with AMC1735, and snug a 26650 inside.
Still in doubt of running it 1.4A or 1.75A. The less, the easier the soldering :).

On closer analyzing back focal length seems to be around 30mm:
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Edit 2:
I have changed the plastic fresnel for the glass Ahorton aspheric.
More artefacts as it is more clear, but theoretical more lumen out of the front.
It needed 5 to 6 six minutes sanding P180 to get a friction fit in the Delrin cylinder.
For alignment you need to press it in 6 mm to maintain full variable focus.
Beamangles are now 5,9 narrow (was 4,7) and 28 degrees on wide (was 24).

Next step will be building higher amp driver suitable for lipo without selfdrain.
 
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MRTdiver

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Walter can you tell me what is the size of the existing PCB? I wonder if an XP-G2 would be nice upgrade.

It's a good thrower when focused, too bad Cree didn't upgrade the XR-E to an XR-E2 like the XP-E2.

re. pic 18 with the 6014 chip. Is this an IC that controls amperage, similar to an AMC 7135 regulator, but smaller? Can this be piggybacked with another 6014 for more amps? I mean stack another on top by soldering.
 
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DIWdiver

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re. pic 18 with the 6014 chip. Is this an IC that controls amperage, similar to an AMC 7135 regulator, but smaller? Can this be piggybacked with another 6014 for more amps? I mean stack another on top by soldering.

The previous posts imply that part is an FET, switched on and off by a reed switch. The actual current control is done by a resistor.

It's very strange that this configuration would drain the batteries while not on, unless the FET is damaged.
 

MRTdiver

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DIWdiver you are very keen on electronics. Thanks for your input.

I'm trying to sell my new Mb-sub, but say I keep it and put in an XP-G2, but keep the original circuit board. I would want it driven harder - probably 1.7 A. I figure it's probably at ~1amp or less with its XR-E. What size resistor would I want? And what would replacing the FET do as you suggested in post 2?

In all the time I've had my other X1-VB I never noticed a drain on my Duracell 3AA cells.
 

arek98

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The previous posts imply that part is an FET, switched on and off by a reed switch. The actual current control is done by a resistor.

It's very strange that this configuration would drain the batteries while not on, unless the FET is damaged.

This 6041 definitely looks like MOSFET. Resistor is not used to control current. Resistor in FET switch is used to pull down gate when switch is open and turn off the FET.
Resisitor could have higher resistance (1002 is 10kOhm, it could easly be 1MOhm) but anyway current thru resistor flows only when switch is on and it should not drain battery when switch is off.

Maybe MOSFET is really damaged and leaks currrent between source and drain when off. Or maybe there is an alternate current path between battery + and -, high resistance short (kOhm range), maybe cleaning can help.

For a driver you could use anything as long as it fits physicaly and you can connect all wires. Parts that are inside are just a switch, you can think about is as regular clicky just directional. Disconnect LED, connect driver - input where LED - (cathode) was (MOSFET drain; thick path on PCB where 4 legs of 6041 part are soldered or solder blob close to ML/2010 on picture 17) and driver + input where LED + was (battery +; somewhere connected to screw on top of picture 17). Driver output to LED. If driver can change modes by power on/off cycle you will be able to use it.
 

Walterk

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The PCB diameter can be 25mm, there is about 25,5mm diameter hole. It gave me 0.77A.

I could be wrong about the selfdrain, but on three occasions I found the output severely low while using fresh Eneloops that otherwise don't show this behaviour within weeks.
I could try to measure some more, and haven't dismounted the led yet as it looks glued-and-screwed in well.

This weekend I made two 1.4A drivers with AMC7135 to no succes. I used diode and new reed contacts on experimenting-board.
Probably overheated the AMC's while soldering them stacked. Could not find what the problem is, but both are faulty in a diferent way.

Thinking of piggybacking two DX 1A AMC7135 drivers, to avoid soldering SMD parts myself. At least gives me time to think while waiting for the mail. If that doesn't work I plan asking DIW-diver to help me out.
 
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DIWdiver

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DIWdiver you are very keen on electronics.

Thank you. From your lips to my boss's ear, as it's how I make my living.

I'm trying to sell my new Mb-sub, but say I keep it and put in an XP-G2, but keep the original circuit board. I would want it driven harder - probably 1.7 A. I figure it's probably at ~1amp or less with its XR-E. What size resistor would I want? And what would replacing the FET do as you suggested in post 2?

In all the time I've had my other X1-VB I never noticed a drain on my Duracell 3AA cells.


As arek98 points out, I missed that the light is designed as truly direct drive - no resistor to limit current. I should have been paying closer attention if I'm going to offer advice.
The consequence of this is that the light is harder to mod. That's because in the original design, the current control is done largely by the batteries. More precisely, it's the internal resistance in the batteries that limits the current to a safe level when the batteries are new. Once you put a lithium cell in there, the internal resistance is much less, and you have nothing to limit the current and prevent the LED from getting fried.

It is possible to build a direct drive light with lithium cells, but I don't know that much about it, because I have little interest in that technology. There's no electronics, thus the lack of interest. It also offers little control over the light output, and guarantees that the output will start high and fall continuously over the life of the battery. That's not the way I want my lights to work. It's the way flashlights have worked since the dawn of flashaholism (i.e. virtually all incandescent lights work this way), but today is a new day....

It would be quite reasonable to build a driver that would fit in that space and give you up to 2A regulated drive, but it would be a lot of work. If you wanted to stay direct drive and replace the FET with something known, I would choose the Vishay Si3477DV. It's not expensive, fits the board as designed, and will handle 2A with no problem.

I actually recently built a light that is very similar, using a 22650 LiIon cell, XM-L led, and Ahorton aspheric lens, focusable. I was unsatisfied with the mechanics of it (sand got in and bound up the focusing mechanism), but was very happy with the light output. I should be talking you out of modding this light so you'll sell it to me cheap and I can mod it myself to what I want! But you should be holding tight to this body and figuring out how to get the output you want. I'll offer whatever help I can.

D
 

MRTdiver

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and haven't dismounted the led yet as it looks glued-and-screwed in well
I heard of a modder putting lights in the freezer, then he said the glue cracks off easy with a screwdriver. I'm sure someone will comment if this is a dumb idea.

The PCB diameter can be 25mm, there is about 25,5mm diameter hole. It gave me 0.77A...
Thinking of piggybacking two DX 1A AMC7135 drivers, to avoid soldering SMD parts myself.

So approximately a 25mm MCPCB is what your saying. I was hoping the LED was mounted on a 20mm so I could do a quick and easy swap, since that is a common size they come in. And I see the PCB is screwed on (pic).

For the driver you could use one board, like an AMC7135x8 @ 2.8A, then remove 7135s (350 ea) for your desired amperage (-3 ICs would give you 1.75A). For this in single mode see e.g.: Lightmalls sku: M0123

If the existing amp draw at the emitter is 0.77A, then I wonder if running this on 3 x Energizer L91 (datasheet) would give me a little more amps? When I measure the volts they come new at ~1.8V.

I'm also considering that the stock circuit is direct drive and the internal resistance of the L91s MAY be less than regular alkalines.
Well I guess the impedance is about the same. Energizer lithium vs. Duracell alkaline is...
90-160 milliohms (depending on method) vs. 120 milliohms respectively (Duracell AA datasheet)

Once you put a lithium cell in there, the internal resistance is much less, and you have nothing to limit the current and prevent the LED from getting fried.
Yeah, I realize your talking about Li-ion batteries. Even though they're superior, I was looking for ways to avoid using them, because as you said, it would be a pretty in-depth modification - new driver & placement etc.
 
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Walterk

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The MCPCB is as common as it gets; 19mm.

Keep in mind the magnetic switch is not a momentary action.
I don't see how the suggested driver would work with single mode?


I measured the O-rings:
2 pieces 2,5 x 32,5mm
3 pieces 2,0 x 34mm
 
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Walterk

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Have been fiddling with the driver recently.
The idea is to run 2x 0.75A AMC135 DX-driver (SKU: 26109) from a single 18650.

I did not re-use the bolt in the center for contact but soldered a spring on the back of the driver.
Got it to work partly; somehow the led kept glowing faintly until I removed the battery.
I suspected the magnetic reed to stick, so I tried diodes in every possible position, to no succes.
Or maybe the hot-glue I have is not a good enough resistor and making a false contact.

Any suggestions?
Does the reed need provisions to do its job?



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DIWdiver

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So the + end of the battery is at the tail end of the light, and the - side is up against the driver?


If so, then it looks like you have it wired correctly. The pin on the driver that you connected to the reed switch isn't really intended as an on/off control, but it should work that way. Perhaps if you connect a 1K resistor from there to "-" (blue wire in your drawing), it might make the light shut off better.
 

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