# Help, I fried my Magicshine



## isleblue65 (Sep 5, 2009)

I did something really stupid today. I had two batteries in my Camelbak; one for the Magicshine and one for a Halogen Planet Bike light. Both cords were sticking out of the pocket and both lights on my helmet. Both plugs look about the same and are the same size:madman: 

So, you guessed it, I plugged the wrong battery into the Magicshine and after a few seconds the smoke puffed out of its housing. It still lights up -- barely, but very dim and the button does nothing. You can see the damage in the photo below.

Can any of the gurus tell me if there is anything I can do to salvage my light, what I have to replace (what this burnt part is supposed to look like) and if there is a possibility of fixing it?

I've only had the light 1 week and used it twice, and now I go and fry it!

Any help appreciated!

Thanks


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## piesoup (Feb 9, 2009)

:madman: :madman: :madman: 
Oops! You'll most probably have to replace the whole driver. Speak to Geoman, I'm sure he'll be anle to tell you what the driver is. I'll have a look on DX now and let you know if I find anything.


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## WeakMite (May 11, 2004)

Magicshines are so inexpensive that by the time you buy a new driver board (likely not available separately) and installed it, or paid someone to install it... you'd be getting close enough to the price of a whole new one...

Especially if Geoman (after the next shipment) resumes selling the Magicshine lighthead only.

It used to be listed on his site for $*45*... that would sound like a pretty nice option for you right now. :thumbsup:

Geomangear isn't showing it anymore, but here's the google cashed version of the lighthead only page: https://74.125.113.132/search?q=cac...4_41&products_id=143&cd=1&hl=en&ct=clnk&gl=us

Maybe get hold of him and ask about it.


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## El34 (Jan 11, 2009)

Oooo, that's ugly.  

I have the driver board that I removed from my DX light.
You can have it if you want it.

I toasted mine also, but that part you are showing is not burnt.
My reflector tipped to the side and shorted out the LED + and - wires.

Don't know exactly what is bad on mine, but you may be able to get one board running.

It may not be worth the effort to try and create a good board from two boards.

PM me if you want my board.


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## Turveyd (Sep 30, 2007)

Atleast it's cheap, if you'd done that to the Lupine Tesla you'd still be crying about it.

Buy a 2nd light there cheap, atleast you'll have spares to fix the next 1 that dies


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## isleblue65 (Sep 5, 2009)

It would be great to find the whole board and just solder the power wires onto it, but I don't suppose Magicshine is in the business of sending replacement boards. I'll check with Geoman. In the mean time, I've PMd EI34 about his board. Maybe I can fix it with that. Otherwise, the light head alone option would save some money over a complete new unit.

I do a fair amount of soldering for a living, so I'm not worried about being able to replace that little chip (once I can identify what it is). It would then just be a question of whether or not that (and the black power wire) are the only things that are damaged.

Does anyone have a photo (or can take a close up of this area) that might show what it looked like before it caught on fire?


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## El34 (Jan 11, 2009)

I sent the driver board out to you.
Good luck with your repair job

I have photo's of the inside of the DX light here on this page
http://www.el34world.com/Misc/bike/BikesLights35.htm


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## [email protected] (Mar 28, 2007)

The part you fried is an N channel mosfet, I think it's a dual mosfet (2 transistors in a small 8 pin soic package). When I opened mine up, I couldn't even find a part number on it. You could try replacing it with a FDS6961A, made by Fairchild semi. You can probably order one from Digikey.

If you have never done surface mount soldering before, this is probably a bad project to learn how on.

I also can't figure out how a different battery pack would blow just the mosfet unless it had a different polarity, but that would probably have fried lots of other components as well. When you plugged the wrong battery in, did the light come on for a few seconds before the smoke leaked out? If it did then you might not have fried too much else.

My advice would be to replace the whole light-head if you can. You might be able to sell/donate the burned out one to someone on this board interested in making a more durable light out of it.

Mark


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## El34 (Jan 11, 2009)

I ended up building a custom simple resistor Hi-Lo board for my DX light.

I reconfigured the battery pack to 3.6 volt 4 x 18650 in parallel

more info here on my simple resistor boards that I make for the Marwi's
http://www.el34world.com/Misc/bike/BikesLights40.htm

I don't really need anything but a low for climbing and a high for the descents, so it works for my needs


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## isleblue65 (Sep 5, 2009)

Thanks for the info. Is the part like a prom, with multiple legs each soldered to the board? I could see how that would be a challenge. Nevermind, I found it.

When I plugged in the wrong battery nothing happened. No lights, no flickering, no green LED button lit up, etc. After about 2 seconds of nothing, I pressed the button on the back of the MS light head and that's when I first saw smoke. Not that that necessarily initiated the damage, but after pressing the button is when the smoke first appeared.

I'm hoping that the fact the LED does light up (however dim) on the Magicshine using the correct battery, that this might indicate that the damage is limited to this one part. I'll see if I can source the part.

I've also sent an e-mail to Geoman asking if he can source a whole new board. I can handle soldering in the 4 power wires (in from battery and from board to LED), as those look like the only wires coming into/ off from the board.

If I can't fix it, this would give me a good winter project to try and build my own better light!



[email protected] said:


> The part you fried is an N channel mosfet, I think it's a dual mosfet (2 transistors in a small 8 pin soic package). When I opened mine up, I couldn't even find a part number on it. You could try replacing it with a FDS6961A, made by Fairchild semi. You can probably order one from Digikey.
> 
> If you have never done surface mount soldering before, this is probably a bad project to learn how on.
> 
> ...


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## isleblue65 (Sep 5, 2009)

Digikey's minimum order of 2500 FDS6961A makes it a little challenging! 

Is there anyplace I could buy one or two?


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## mtbikerTi (Jan 15, 2004)

Try Mouser:

www.mouser.com

http://www.mouser.com/ProductDetail...=sGAEpiMZZMveMCOqFR6qCKWVpUaydojU7uZzlP8ziSc=


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## isleblue65 (Sep 5, 2009)

mtbikerTi said:


> Try Mouser:
> 
> www.mouser.com
> 
> http://www.mouser.com/ProductDetail...=sGAEpiMZZMveMCOqFR6qCKWVpUaydojU7uZzlP8ziSc=





El34 said:


> I sent the driver board out to you.
> Good luck with your repair job
> 
> I have photo's of the inside of the DX light here on this page
> http://www.el34world.com/Misc/bike/BikesLights35.htm


:thumbsup:

Thanks to both of you!


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## christexan (Jun 1, 2004)

Good luck, clearly the driver board is fried, however the dim glow suggests voltage is getting to the LED through some route (which might be direct from the batteries)... try disconnecting the leads to the LED and use a "coin cell" battery or 2-AA alkalines in series to see if the LED lights up somewhat brightly. Unfortunately an all-too-realistic scenario is the control board blew, which "open-circuited" the inductor, which might then unload unrestricted into the LED (forward, or worse, backwards), which could then be "blown" itself. Many shorted LEDs will remain faintly glowing after a dead short, basically some tiny fraction of the die remaining functional but most of the functional area is "stripped off" by the surge of voltage across it. (Picture a wave across a sand castle)
Anyhow, I would just verify first the LED isn't blown using a low-current capable 3V source (as described above), before spending a lot of time and effort on repairing the driver board.


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## isleblue65 (Sep 5, 2009)

I made a couple of discoveries tonight. One is that my LED is working fine. I hooked up a coin cell battery to the disconnected LED and it lit up bright.

The second discovery is that my driver board is trashed. After scraping away the burned remains of the mosfet resistor pack, a deep hole that burned half way through the board was revealed. All of the copper board circuitry is burned off all around this area.

I ordered a couple Mosfet packs but it looks like they will do me no good. I'm hoping I can do something with the board that I get from EI34 - otherwise I'm going to try making my own board and use the still OK LED from my Magicshine. I too really only use low and high.


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## El34 (Jan 11, 2009)

My board I sent you is super clean, looks like new.

I am not a wiz when it comes to solid state components so I don't know what I trashed on my board.

Maybe someone else can figure out which part I fried when the reflector shorted out the LED + and - 

Again, what happened on mine is the reflector tipped to the side and made contact with the LED + and - solder points. That white plastic washer/ring behind the reflector is an insulator to keep that from happening. They cut the holes in the reflectors way too big for a P7 and so they do not sit firmly on that black plastic ring that surrounds the LED Lens.

I machine reflectors on my CNC that fit perfectly around the Marwi conversion P7's. Not really a problem is the reflector hole is properly sized. You just have to make sure you keep your solder joints low on the LED board surface, with no giant blobs of solder.


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## wkumtrider (Dec 27, 2007)

Why don't you just buy a buck puck or a board from taskled to replace the fried board?


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## El34 (Jan 11, 2009)

The space available in the MS lights is very limited.
I just replaced my original driver board with a simple resistor board.
I had to remove the brass ring and open up the alumnum heat sink just a bit with my lathe.

The total height from switch plunger tip to bottom of my board is about .31" or 7.8mm

Not sure how other boards would fit, just throwing out some info.
you have to be able to get the switch into the center of any board you install.

Here's a couple pics showing the total stack height.
The switch plunger tip just contacts the blue rubber switch tailcap on the MS light


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## isleblue65 (Sep 5, 2009)

I use a Bridgeport mill and lathe every day at work building machines. If simply turning the MS heat sync would allow me to use a simple resistor board in my MS head, then it would seem this would be a good option. Or did you use the MS heat sync inside the Marwi head unit? I would welcome the option to do a little machining if this would allow me to save some money by utilizing my MS light head and not having to buy another, or build another from scratch.

Before I get too far though, I am interested in hearing suggestions on what might have shorted out when EI34 crossed the +/- wires on his MS LED? I plan to check resistance across resistors and components on his board compared with the same parts on my board (assuming all parts on mine except the destroyed one are still good), and then replace parts that have different resistance on his board. Knowing what specifically to scope in on would save time and trial and error work however. If all this fails, I'll either buy a new light head or build my own. I haven't heard back from Geoman on the replacement board yet.


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## El34 (Jan 11, 2009)

I removed the brass ring so I could get my driver board to sit down into the MS heat sink a bit lower. You need all the front to back clearance you can get, space is tight.

I have already had a few people ask me about this driver board, here's the scoop.

It is a simple resistor Hi-Lo design.
I made this board custom, it is bigger in diameter than the Marwi boards I make.
You have to reconfigure your battery pack from 7.2 volts to 3.6 volts. All batteries in parallel.
Your charger is no longer any good because it is a 7.2 volt pack charger.

I doubt many people want to go through all that mentioned above and so I have no plans to make this board.
More info here on that board.
http://www.el34world.com/Misc/bike/BikesLights40.htm


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## MtbMacgyver (Jan 23, 2007)

The FET that's driving the buck regulator is what likely burnt up on EI34's board. I didn't spend time looking carefully at all the components on the driver board when I torn my magicshine light apart and re-assembled it. But I suspect it's the same part that totally self destructed on your board. You really need to get the part number off a board for the original part, find a data sheet for that part, and match the specs up to something equivalent. I can almost make out the part number from the picture on EI34's site....but not quite. If I had the numbers and symbols off the original part, I'd be happy to try and match that up to an available equivalent part.

It's not impossible to remove and replace a surface mount part with a regular soldering iron, but it's gets harder as the pin count on the device goes up. It's much easier to do if you have a hot air re-work station. 

It's kinda a shame EI34 already mailed his broken board to you. It looks like he lives in one of my favorite places to ride. Because I'm curious about the design of the driver in the MS light, I could have picked it up from him next time I'm in that area, attempted to fix it, and sent it too you.


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## El34 (Jan 11, 2009)

Heheheh, yes Pisgah Forest is right out my back door.
I moved here in 2001 just because of the riding.
riding in Pisgah is freaking awesome. 

Check out this heinous stage race event coming up in the next couple weeks.
Supposedly some pro's will be here for it
I heard Tinker was coming.
They will be riding right past my house on stage 3.
http://www.blueridgeadventures.net/stage/main.html


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## isleblue65 (Sep 5, 2009)

MtbMacgyver said:


> It's kinda a shame EI34 already mailed his broken board to you. It looks like he lives in one of my favorite places to ride. Because I'm curious about the design of the driver in the MS light, I could have picked it up from him next time I'm in that area, attempted to fix it, and sent it too you.


Thanks for the offer. I'd be glad to post the numbers on the board or other components once I get the board. As I said, I'll be getting a couple of the replacement Mosfets that Mark mentioned near the top of this thread, and if I knew how to diagnose the Mosfet on EI34s board, it wouldn't be too much to replace it. I have a Weller soldering station at home and Hakos at work along with microscopes and skinny soldering tips, so I'm ready for the job -- I think.

EI34, I had forgotten that you mentioned about the battery pack reconfig and that the charger would have to be replaced. That probably tips the scale toward buying a new light head from MS if I can't fix mine.


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## El34 (Jan 11, 2009)

yeah, it's a bit more work than most people are willing to do.
That's why I didn't even bother to mention my MagicShine conversion here before.

Better off just getting the driver board working or getting a new light set.


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## isleblue65 (Sep 5, 2009)

Thanks for sending the board EI34. Got it today.

Here's a picture of the Mosfet in question from your board. Maybe MtbMacgyver can figure out if the Digikey Mosfets are the same ones. I have a pack of 5 new Mosfets from Digikey in front of me (the ones mentioned earlier in this thread). 

EDIT: Just looked at it under the scope and the numbers are: 

4822
BA9SCS

Found nothing on the Web using these numbers, and the logo that looks like a cross between an 'A' and '@' symbol isn't any manufacturer I'm familiar with.

One of the problems with your board (may be able to make it out in the photo) is that 2 of the Mosfet legs are soldered together. It looks like you may have done this by mistake when doing something else to the board. Also, the switch was broken in pieces and only 1 leg soldered to the board. This may have happened while en-route. If I can replace the mosfet and switch, I think there's a decent chance it will work again. No way I can do this at home. I'm going to solder under the scope at work.

The good news is that the mosfet looks fine. The resistor that the LED leads go to however is cracked. This could only be seen under the scope as the crack starts from the bottom side, but it is cracked almost all the way through. I'm going to leave the mosfet alone and replace this resistor along with the switch and see what happens.


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## El34 (Jan 11, 2009)

No, I remember seeing the solder bridge on that mosfet.
That was the way it was when I opened it up and had a look..
Maybe someone else can tell us if theirs is like that also.

Maybe that's why my MS light never looked that bright.
I thought I had trashed the board before I took it out for the beam shots.

The switch must have gotten smashed in the mail.
One if the reasons I don't ship parts in bubble wrap envelopes at my store.
Sorry about that, this was free and so I had to ship it the cheapest way.
Hope you can salvage something off the board.

see ya


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## isleblue65 (Sep 5, 2009)

El34 said:


> No, I remember seeing the solder bridge on that mosfet.
> That was the way it was when I opened it up and had a look..
> Maybe someone else can tell us if theirs is like that also.
> 
> ...


Glad you remember seeing the bridge as I have nothing to reference. Could someone else please post a close-up photo of this mosfet from their board?

I'm going to give it one try at work to replace these parts and then it's either a go or no go.

I'm not upset at all about the switch, so hope you didn't think I might be Things happen, and I'd never have even a chance at salvaging this light if you didn't have this board that you sent. Much appreciated!

If it doesn't work I'll talk to you about your Marwi conversions. I already have a working LED from the MS, so I'd just need to price out the other components/ housing vs buying another MS light head. I might build up a Marwi anyhow.


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## MtbMacgyver (Jan 23, 2007)

isleblue65 said:


> Thanks for sending the board EI34. Got it today.
> 
> Here's a picture of the Mosfet in question from your board. Maybe MtbMacgyver can figure out if the Digikey Mosfets are the same ones. I have a pack of 5 new Mosfets from Digikey in front of me (the ones mentioned earlier in this thread).


The part is an Alpha & Omega AO4822 Dual N-Channel Mosfet. The little diagram to the left of the numbers 4822 is their logo. It's a "A" inside of a partial "O".

Here's a link to the part at digikey

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=785-1060-2-ND

The two pins that are bridged together with solder are pins that are connected together within the device and they should be connected together on the PCB. If they have extra pins in the package, they use multiple pins for the same connection to better handle higher currents. Either the PCB doesn't have those pins connected and they solder bridged them as the "fix", or the solder bridge was an accident but the person that did that knew it didn't matter because the pins are suppose to be connected.

The fairchild part that was mentioned earlier in the thread does have the same pin arrangement. So it will potentially work to some extent, but it doesn't have the same current rating and more importantly Rds(on) specs. Explaining the ramifications of the different Rds(on) spec gets pretty complicated so I'll just tell you the net of what may happen if you use the fairchild part. It may get too hot and burn up under normal operation. Since I don't have the overall schematic of the driver I can't really tell for sure, but knowing P7's 2.8A rating the fairchild part probably isn't up to the task.

Here's what I would do at this point. Go ahead and try putting the fairchild part on the board. It should work well enough to figure out if the driver is basically working or not. You need to look over the board really carefully for burned up PCB traces and repair any damage. If you get it working, you can see if it seems to work right. You can also feel that mosfet and see if it's getting hot. If everything else is working, I'd order the right part from digikey and replace it again.


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## MtbMacgyver (Jan 23, 2007)

I posted the link to a full reel above. Here's the correct link for single parts.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=785-1060-1-ND


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## isleblue65 (Sep 5, 2009)

Thanks MtbMacgyver. That information is helpful. I think to start with I am going to just replace the switch and the part that the other end of the wires from the LED is soldered to on the circuit board -- not sure what it is called. That part on EI34s board has a crack that extends almost through the whole chip from the bottom toward the top. The one on my board (newer board probably) is not only a different chip, but is not damaged. I'm thinking that some heat was generated when EI34 crossed the +/- wires on his LED and cracked that chip. 

If it still doesn't work after replacing that, I'll replace the mosfet.

I'll report back.


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## isleblue65 (Sep 5, 2009)

After replacing the switch and the other component which is actually the resistor that the battery wires are soldered to (not the wires to the LED), the light functions but very dimly. The switch controls all 3 functions (low, high and flashing), but the LED is very dim.

I noticed that not just 2, but 3 of the Mosfet pins are soldered together on the same side. I would really like to know if this is correct? 

Obviously something is preventing full battery power from reaching the LED. None of the other components on the board look physically damaged or discolored.

I think I'm really close to salvaging this light, but a key piece of information is missing somewhere.


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## El34 (Jan 11, 2009)

Looks like you are making progress


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## [email protected] (Mar 28, 2007)

If the mosfet pins soldered together are all on the same side, I wouldn't worry about it. The ones soldered together in the picture you posted are on the drain side of the mosfet, and all those pins run to the inductor if I remember the circuit correctly.

If you have a scope, you could measure the voltage across the resistors used to set LED current (you mentioned one of these was cracked). It should look like a triangle shaped signal with an average value of around .2 volts (that's differential voltage across the resistor, not voltage with respect to the ground on the driver's pcb.) If that's there, Then the driver chip might be working correctly. I'd then look at what resistors did you use to measure LED current. If they are too large (resistance wise) then very little current will flow, which would explain your symptoms. The 2 resistors in the unit I have were originally 0.1 ohms and 0.5 ohms in 0805 sized packages. You might try touching up your solder joints at the ends of the resistors, a cold solder joint will mess things up. Use a lead based solder if you have one.

Take a look at this thread: http://forums.mtbr.com/showthread.php?t=527707 (around post 15) where I discuss how the resistors used to measure current are woefully undersized (physically). They need to be larger in size to dissipate the heat generated in them. If you search on digikey for .18 and 1206 you can get to a list of 0.18 ohm resistors in a 1206 size package. These are a bit larger than the 0805 sized parts on the driver board. I managed to get two 1206 sized resistors soldered down where the old ones were. The larger resistors won't run as hot. 0805 sized resistors are at best rated to handle .125 watts. If you run 2.5 amps thru a 0.1 ohm resistor, it will need to get rid of .25 watts of heat.

With regard to using the FDS6961A mosfet. MtbMacgyver is correct that is is not as nice a part as the AO4822, but I never found that one while searching on digikey for dual channel mosfets. I was just trying to find a pinout diagram for the mosfet. I think the FDS6961A will probably work. It has a much lower gate charge than the AO4822, so switching losses will be less, but it has a RdsOn about twice that of the AO4822, so it will probably use up around .2 watts where the AO4822 may use up .1 watts. I don't think it will make much difference. Try it and see if the mosfet gets really hot. Use a thermocouple to measure temperature. If the mosfet stays under 60C, you'll probably be fine.

Hopefully you are ordering all these parts from digikey on your boss' shipping account or the shipping charges will be 4 or 5 times more than the cost of parts you are buying.

Good luck,

Mark


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## isleblue65 (Sep 5, 2009)

[email protected] said:


> If the mosfet pins soldered together are all on the same side, I wouldn't worry about it. The ones soldered together in the picture you posted are on the drain side of the mosfet, and all those pins run to the inductor if I remember the circuit correctly.
> 
> If you have a scope, you could measure the voltage across the resistors used to set LED current (you mentioned one of these was cracked). It should look like a triangle shaped signal with an average value of around .2 volts (that's differential voltage across the resistor, not voltage with respect to the ground on the driver's pcb.) If that's there, Then the driver chip might be working correctly. I'd then look at what resistors did you use to measure LED current. If they are too large (resistance wise) then very little current will flow, which would explain your symptoms. The 2 resistors in the unit I have were originally 0.1 ohms and 0.5 ohms in 0805 sized packages. You might try touching up your solder joints at the ends of the resistors, a cold solder joint will mess things up. Use a lead based solder if you have one.
> 
> ...


Thanks for the info Mark. I assume you mean an oscilloscope for seeing the waveform? I might have one at work, I'll check. Would measuring resistance using a regular multimeter show me anything?

The part that was cracked was the resistor that the incoming battery red and black wires are soldered onto on the board. I replaced the cracked one with the same part from my board, which was not the same part number as the cracked one.

I think I'll start with the mosfet swap and touch up the solder joints and see if that fixes it. If not, then perhaps I'll order up some of those 1206 resistors and replace the 0805s with two 1206s.

After that I'll get a new light head and see if I can build my own light using my dead MS light head.


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## [email protected] (Mar 28, 2007)

isleblue,

Yep, I meant oscilloscope. Sorry, us tech heads talk that way too often. Put the probe and it's ground lead right across the resistors. I find soldering a small test lead that just hangs in the air, to either end of the resistors, usually gives one something to clip the scope to. Be sure to remove these leads when done doing measurements.

The resistor you replaced is one of the two wired in parallel, connected between the red wire (+ input) and the inductor. They are used to measure current by the driver chip. When the voltage across the 2 resistors gets high enuff, a bit above 0.2 volts, the driver shuts the mosfet off, and the inductor's magnetic field collapses and provides current to the LED. The current from the inductor gets lower, and the voltage across the resistors gets lower. When it gets a little bit below 0.2 volts, the driver turns the mosfet on again, which builds the inductors magnetic field back up and provides current to the LED at the same. This is basically how a classic hysteretic buck converter works (OK, OK, I'm leaving out some, but I want to keep this short).

Anyway, you can find a nice data sheet on the driver here: http://www.micro-bridge.com/data/semi-micro/SM5241.pdf

If you read Chinese please tell me what the heck it says  There's a nice circuit diagram on page 4 that is pretty much what the driver board is, except there is a micro and low voltage detect circuit on the other side, and the parts values are different because they are driving lower power LEDs.

Now I have a question about how you swapped parts to replace the cracked resistor that may explain your symptoms. My board came with 2 resistors. 1 was labeled R10, that is a 0.1 ohm resistor. The other was labeled R50, that is a 0.5 ohm resistor. Was the part that was cracked labeled R10? And did you replace it with a part labeled R50? If you did, you have created a 0.25 ohm current sense resistor (two 0.5 ohm resistors in parallel is exactly half the resistance). This will hit 0.2 volts with about 0.8 amps running thru it, which would nicely explain your dim light. You are running roughly 1/3 of the current thru it that it was designed for.

If this is what you have done, you might want to try unsoldering one of the R50 resistors and soldering in an R10 resistor. If your light looks nice and bright after that, then you can be pretty sure the driver chip is OK.

It's still worth (if your boss can afford the shipping  ) some of the physically larger 1206 size resistors (even 1210 size parts will fit), as they don't heat up as much, or at least have more surface area to dissipate the heat. And if you put 2 in of the same value, they will share the current load. Using an R10 and an R50 will result in 2 amps running thru the R10, and .4 amps running thru the R50. Two R18s would have about 1.11 amps running thru each.

Don't bother trying to measure the resistors with a multi-meter unless you have a nice lab style one. My cheap $40 one measures .5 ohms when I short the leads together, and drifts around from there. It's pretty useless for measuring .1 ohms.

Hope the repairs go well,

Mark


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## isleblue65 (Sep 5, 2009)

Hey Mark,
The resistor (or whatever it is) that I replaced is pictured below with the arrow pointing to it. There is only one, not two wired in parralel, and there were no numbers or anything on either the cracked one or the donor. the one in the picture is the cracked one. There are red and black pen marks on it to show where the wires from the battery go. The one on my board was taller and narrower than the one pictured. All I did was removed the cracked one and replaced with mine from my bad board. Other than that part and the switch, I've done nothing else to my board. 

Sounds like you are talking about the little tiny resistors that are about 1mm x 2mm? I have not touched any of these. I'm not sure if I have the electrical savvy to get much further into it. I know I could replace the parts without too much trouble, but I've not played with an O-scope in years, if I could even find one in my facility that works. We do have nice Fluke multimeters so if that could do me any good I'm comfortable working with those.

So for one last hail mary, assuming all I have is a nice Fluke, would you say replace the mosfet with the proper replacement and all of those little resistors with 1206s?

I got those last 5 mosfets as free samples from Digikey, so I don't know how many times I can pull that one. We buy stuff from them, but I have no intention of every buying these mosfets in the quantities they sell them in. Mouser seems to be better at selling onesie - twosie parts, at 3X the price however. But I can handle 1 at .65 cents instead of 2500 at .21 cents from Digikey.


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## MtbMacgyver (Jan 23, 2007)

I'm pretty sure the cracked part you replaced is a capacitor used to filter the input voltage. I agree the current sense resistors are under sized, but that won't stop the board from working and I wouldn't bother with those until after you get the board working. 

Use your meter to measure the resistance of the current sense resistors (R03 and R04). Mhahn is right, a low cost meter isn't all that great at measuring small resistance values. See what the meter reads with the leads touched together. Then compare that to what it reads across those resistors. It should be in the range of .08 more than the reading with the leads touched together. If it's a much larger resistance, then the resistors are damaged.

Next, use the meter to measure the diode in the circuit. Some meters have a special mode for measuring diodes. If your meter doesn't have a special mode, try to set it to measure resistance on a low scale that's in ohms instead of k-ohms or m-ohms. The diode will be a square part with a white line on one end. I think it's under the inductor on that board. You measure it by taking two readings while swapping the meter leads between the two measurements. It should read a low resistance in one direction and a high resistance in the other direction. You should disconnect at least one of the wires from the LED and the power connection to the battery while you measure the diode to keep from measuring other components. If it reads a low resistance in both directions then the diode is shorted out. If it reads a high resistance in both direction then it's damaged as an open circuit. You can compare readings to the diode on the other PCB as a cross check. 

If those tests look good, then I'd try replacing the mosfet with one of the fairchild mosfets.


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## [email protected] (Mar 28, 2007)

MtbMacgyver is correct. The cracked part is a capacitor. If it's a ceramic one, it won't have any markings on it. Mine was a tantalum marked as 476 10R 643, which I think means it's a 4.7 uF cap rated at 10 volts. Replacing it with something that can handle higher voltages would be nice.

MtbMacgyver may be onto something about checking the diode. If you plugged a battery with the opposite polarity of the one the magicshine came with, the mosfet would go bang, because it has an internal diode (called the body diode) that would suddenly be forward biased, and the diode under the inductor would also be forward biased. Battery current would flow thru those 2 diodes until one of them blew. You original picture makes it look like the mosfet lost and blew up first, but the diode may have also been damaged. 

If you try MtbMacgyver's diode test with a multimeter, and the diode appears to be fried, you might want to replace it with something like a SSB43L diode Digikey has them, try to get some samples, and sample the resistors I mentioned earlier.

How have you managed to get free samples out of digikey? I guess if your copmpany orders a lot from them they might do that. I wind up ordering 20 or more of parts I want to try because I figure I might as well spend as much on parts as the postage is going to cost me.

Mark


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## isleblue65 (Sep 5, 2009)

[email protected] said:


> Your original picture makes it look like the mosfet lost and blew up first, but the diode may have also been damaged.
> 
> How have you managed to get free samples out of digikey? I guess if your copmpany orders a lot from them they might do that. I wind up ordering 20 or more of parts I want to try because I figure I might as well spend as much on parts as the postage is going to cost me.
> Mark


My original photo is my board that I burned up the mosfet on. The board pictured in my last post is EI34s board that he sent me. I'm trying to get EI34s board working now and have scrapped my board with the exception of using the switch and capaciter off it. So a damaged diode on his may not be applicable, or if it is, it would be damaged for another reason. His mosfet was never burned up, but it may be damaged from when his LED wires were shorted. There is no visual indication that anything else on his board is bad.

I'm going to do some resistance checks on the board and see if I get high resistance on any resisters and I'll check that diode too. If either seem to be reading off, I'll order the replacements recommended here.:thumbsup:

On the free sample question, I just asked to be connected with their sample department (yes, they have a sample department). They look up the account and then ask for my first item number. I'm not sure what their critera is for samples, but yes we do order a decent amount from them. I tried to get a sample tube of heat-dissipation grease like Arctic Silver, but they said they don't sample consumable products. I'm going to put a small order together this week (of other stuff I need from them) and ask for samples of the high minimum quantity components mentioned here. They have bins of all of these components specifically for sampling, but they may only provide samples to people or organizations who place over a certain dollar amount of orders with them per some period of time.

Thanks!


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## MtbMacgyver (Jan 23, 2007)

I think the diode and mosfet are the most likely parts to have failed when the LED wires were shorted together.


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## isleblue65 (Sep 5, 2009)

MtbMacgyver said:


> I think the diode and mosfet are the most likely parts to have failed when the LED wires were shorted together.


Thanks MtbMacgyver, I'll check that diode and just get a new mosfet and replace it as I have no idea how to test it.

Question: would doubling up (stacking) my R10 and R50 resistors allow them to run cooler? I could use the resistors off my old board. This goes back to Mark's post awhile back where he suggested replacing the stock resistors with 1206 size of the same values for better heat dissipation.


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## MtbMacgyver (Jan 23, 2007)

isleblue65 said:


> Thanks MtbMacgyver, I'll check that diode and just get a new mosfet and replace it as I have no idea how to test it.
> 
> Question: would doubling up (stacking) my R10 and R50 resistors allow them to run cooler? I could use the resistors off my old board. This goes back to Mark's post awhile back where he suggested replacing the stock resistors with 1206 size of the same values for better heat dissipation.


Doubling them up puts the 2 resistors in parallel. You would need resistors of half the resistance value to end up with the correct resistance. So, no using the ones off your old board won't work. But the idea itself is correct. Having more resistors would spread the load. But since you have to buy new resistors, going with the bigger resistors that Mark suggests would be better since they'll have a larger contact area with the PCB.

I was suggesting you try the fairchild mosfet and possibly the diode off your other board so you could try this without having to order and wait for more parts. Then once you know it basically working, then it would make sense to order more parts to really clean it up.


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## Vancbiker (May 25, 2005)

MtbMacgyver said:


> Doubling them up puts the 2 resistors in parallel. You would need resistors of half the resistance value to end up with the correct resistance. So, no using the ones off your old board won't work.


You would need new resistors of *twice* the resistance of the originals. Putting resistors of the same value in parallel divides the resistance in half. Series connection of resistors adds their values for total resistance.


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## MtbMacgyver (Jan 23, 2007)

Vancbiker said:


> You would need new resistors of *twice* the resistance of the originals. Putting resistors of the same value in parallel divides the resistance in half. Series connection of resistors adds their values for total resistance.


Good catch, you're exactly right. My excuse is jet-lag.


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## isleblue65 (Sep 5, 2009)

Thanks for the clarification. I was having a hard time visualizing the parralel vs series layout of resisters. I'll go ahead and mount up one of my mosfets as you suggest and see if anything changes (if the board works) - and also swap diodes from the old board onto the new one if the mosfet alone does nothing.

I looked more closely at the black square under the inductor and it does have a faint line on one end. Couldn't tell if it was white or tan, but it must be the diode.


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## slappomatt (Aug 24, 2009)

why not just get a different driver board? a simple buck puck would work would it not? (im not sure if the batteries are protected) but there are serveral driver options out there from $15-35.


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## isleblue65 (Sep 5, 2009)

slappomatt said:


> why not just get a different driver board? a simple buck puck would work would it not? (im not sure if the batteries are protected) but there are serveral driver options out there from $15-35.


I would be fine with that, but was under the impression (I've been told and have read) that the MS board is smaller than buck pucks that are available, and the buck pucks won't fit in the MS light head. The batteries would have to be changed around to work in series instead of parrallel.

The MS board is 0.865" diameter. I haven't personally looked into what's available in a buck puck. Maybe I will.

Thanks


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## MtbMacgyver (Jan 23, 2007)

isleblue65 said:


> I looked more closely at the black square under the inductor and it does have a faint line on one end. Couldn't tell if it was white or tan, but it must be the diode.


Just to be clear, it really matters which way the diode is mounted on the board. Make sure the white line stays in the same position.


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## isleblue65 (Sep 5, 2009)

*Update; still not working*

With the battery and LED wires disconnected I checked my diode and on the new board got low resistance in one direction and high resistance in the other. The numbers were: 2.5 M Ohm in one direction and 0.943 K Ohm in the other. Sounds like the diode is good. My Fluke meter reads 2 Ohms with the leads touching.

On my old burned out board, the diode measured 0 in one direction and 0.981 K Ohm in the other. Sounds like that diode is burned out.

The small resistors (0.1 and 0.5 ohm) measured 1.2 K Ohm and 1.3 K Ohm. I'm not sure how close this is to what the actual numbers should be. On my old board, the readings were about the same.

I soldered in the new mosfet, plugged in the battery and the light operates exactly as it did previously - very dim but the switch controls high, low and flashing modes. 

I'm guessing it might be one of the other components - maybe on the switch side?

I'm thinking it might be time to buy another light head (if Geoman still can get those) and start thinking about how I can build up a new light in my MS light head with an external buck puck controller.

Thanks to all for walking me through the repair attempt.


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## MtbMacgyver (Jan 23, 2007)

I figured I'd respond here since there were others involved in the discussion that may want to know the outcome. I got time tonight to sit down and look at the driver board you mailed me. We were on the right track near the end. The problem turned out to be the 0.1 and 0.5 ohm current sense resistors. They were both damaged with very high resistance values. That probably happened when EI34 accidentally shorted out the LED. It likely took out the mosfet and the current sense resistors. The resistors from your old board were good. I swapped them and it's working great now. Goes through the modes, looks like the correct brightness at each level, and the current draw into the driver is right. The fairchild mosfet worked fine for the minute I ran it. But I'll run it a little longer and see if it heats up. Then I'll drop it in the mail back to you.


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## isleblue65 (Sep 5, 2009)

Wow! What can I say but THANK YOU!! That is great news. 

I truly appreciate your efforts with this.

And thanks for posting the follow up here. 

Again, Thank you.


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## El34 (Jan 11, 2009)

Wow, nice work!

If I had some sort of circuit schematic I may have attempted to trouble shoot it, but I had no idea how that cicuit worked.

Glad it's up and runing again and has a new life!


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## isleblue65 (Sep 5, 2009)

Thanks to you for donating your old board. Without that, this would have been a lost cause.:thumbsup:

I hope I can return the favors folks here have done for me sometime.



El34 said:


> Wow, nice work!
> 
> If I had some sort of circuit schematic I may have attempted to trouble shoot it, but I had no idea how that cicuit worked.
> 
> Glad it's up and runing again and has a new life!


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## mark-essex (Oct 31, 2006)

*Magicshine*

Sorry to jump on this thread but there seems a lot of knowledge here.

I received my Magicshine last week, used it twice to commute, fantastic. Charged up fully last night and connected to lamp, it worked, I switched it off and unlpugged it. Cam out this morning, connected the cable...nothing, not even the green light on the back. I put the battery back on the charger and the LED remained green, even if it was fully charged I would have expected it to change to red for a few minutes.

I'm thinking the battery is at fault but I have limited knowledge of these things. After waiting a month for delivery, and needing a light to commute with this time of year I can't believe I will have to wait up to 2 months for a replacement procedure (not sure how it works but I have emailed them).

Does anyone have any suggestions as to what could be wrong and what I could do other than sending it back?

Thanks in adance for any comments or help.

Cheers, Mark


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## jetigm (Apr 14, 2009)

Try to reconnect the power connector many times. I my case this power connector was very bad, have а bad contact.


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## isleblue65 (Sep 5, 2009)

*MS back up and running!*

MtbMacgyver ended up replacing not only the under rated Mosfet I had installed with the correct one he got from Digikey, but he upgraded the resistors with 0.6 Ohm 1206 resistors. The board runs cooler now and works great.

I re-assembled my MS control board (soldered in plug and LED leads) and installed it back into the light head. I used plenty of Arctic Silver thermal compound in thin layers on the underside of the LED mount plate and on the threads and face of the retaining ring that holds the LED plate down inside the housing. Compared to my completely stock MS light, this repaired one transfers the heat much better out to the light head, and it is warm within 30 seconds.

It lights up bright and clean, and I'm excited to try out my 2 Magicshines together for the first time on the trail.

Thanks again MtbMacgyver, EI34 for the donor board and everyone who helped along the way.:thumbsup:


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## slidecontrol (Apr 8, 2007)

mark-essex said:


> Sorry to jump on this thread but there seems a lot of knowledge here.
> 
> I received my Magicshine last week, used it twice to commute, fantastic. Charged up fully last night and connected to lamp, it worked, I switched it off and unlpugged it. Cam out this morning, connected the cable...nothing, not even the green light on the back. I put the battery back on the charger and the LED remained green, even if it was fully charged I would have expected it to change to red for a few minutes.
> 
> ...


minor dredge: I had a similar issue with my magic shine, turned out to be a broken solder joint from the "battery in" wire to the driver board. ( I was initially blaming the battery at first as well )


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## unikum (Dec 21, 2009)

*Same problem with Dual Mosfet*

I am totally stoked to read this thread. I too have the magicshine, actually two of them. What broke mine was me screwing with the current regulating resistors (0.1 Ohm and 0.5 Ohm) trying to increase the current and light output, and ended up burning up my second light or what turns out to be the mosfet. What caused me to screw with it in the first place was that my second light, which I bought two months after my first one, was noticably less bright. Comparing my old to my new one, it turns out that DX's supplier is using a cheaper, single Mosfet instead of the dual mosfet. My guess is that this causes less current to flow and hence the light not to be as bright. The resistors are the same value on both boards. I've been trying desperately to figure out the supplier of the dual Mosfet so I am very happy to learn that this riddle has been solved. Thanks for posting this and I am going straight to Mouser to buy the parts.


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## charszmasaj (Apr 15, 2009)

isleblue65 said:


> MtbMacgyver ended up replacing not only the under rated Mosfet I had installed with the correct one he got from Digikey, but he upgraded the resistors with 0.6 Ohm 1206 resistors. The board runs cooler now and works great.
> 
> I re-assembled my MS control board (soldered in plug and LED leads) and installed it back into the light head. I used plenty of Arctic Silver thermal compound in thin layers on the underside of the LED mount plate and on the threads and face of the retaining ring that holds the LED plate down inside the housing. Compared to my completely stock MS light, this repaired one transfers the heat much better out to the light head, and it is warm within 30 seconds.
> 
> ...


Thanks to all posters but big kudos to MtbMacgyver! I had similar problem like El34 - shortened led wires. After finding this thread by accident I was able to repair my MS.
In my case it were only resistors. Measured them with cheap multimeter - more than 2k they had. Replaced with one 10 Ohms I found on old motherboard.
Gonna look for supplier for correct ones. Will use bigger ones as suggested.


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## charszmasaj (Apr 15, 2009)

Could only supply R390 1206 0.25W resistors. I did put 5 of them, giving 0,078 Ohm which gave me around 2.7 A. 15 minutes stress test without air flow, lamp survived without problem, although I did some minor modding. Added more thermal compound between P7 and mounting pcb and added thermal compound between inside aluminium block and main body. Wish I have high value thermometer.


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