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Discussion Starter · #1 ·
Hi,

My Magicshine did something weird a couple of days ago. It does not want to toggle to the other settings and remains on the lowest light output.

Since it is an auxiliary light (I have another set I use as primary and only turn this on when it gets exciting... helmet mounted), I don't mind if it is on the high setting. I finally took it apart and I see the wire leads go to the board and from the board, two wires go to the LED. Question is, can I just bypass the board and go straight to the LED (all 7.8 V going straight to it). Will this work? I still plan to leave the board in there as heat mass if I were to do this. If this does work, I might even splice a switch so I don't have to unplug the cables (the switch does not work anymore either).

Appreciate the help.
 

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Discussion Starter · #6 · (Edited)
Vancbiker said:
No, you can not wire the LED direct. The board is current regulator (adjusts output voltage to maintain constant current). The Vf of the LED is ~3.7V and it is rated at a max of 2.8A. If you rewired your pack to a 4P configuration (3.7V), it might work without going up in smoke.
Thanks, I may just end up doing that. Do you know the current draw (or wattage) of the LED? Just want to estimate how much one cell might last.

Actually, I can also fashion a voltage regulator that puts out 3.7V, right? That way I can still use the old pack. Or if I just know the board schematics, I can probably jump it somewhere to take advantage of the step-down transformer.
 

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Discussion Starter · #8 ·
nick d said:
you can get a lighthead pretty cheap
Yeah, I'll be buying anothe lighthead regardless. I just don't want to throw away this one just because of a faulty board.
 

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ron m. said:
Thanks, I may just end up doing that. Do you know the current draw (or wattage) of the LED? Just want to estimate how much one cell might last.

Actually, I can also fashion a voltage regulator that puts out 3.7V, right? That way I can still use the old pack. Or if I just know the board schematics, I can probably jump it somewhere to take advantage of the step-down transformer.
In my original post, but here it is again. The LED is a SSC P7. It has a Vf of ~3.7V. It is rated at 2.8A though Magicshines typically run it at 2.4A. A single 18650 cell will typically run the P7 directly. That is because the internal resistance of the cell prevents it from delivering more than 2.8A It will run pretty well for ~1 hour before dimming too much.

LEDs need current regulation not voltage regulation. There is no transformer on the board. The device that kind of looks like a transformer is an inductor. If you want to fix it, your best bet is to search the lighting threads for others that have dead MS lights and worked out ways to fix them (there have been many).
 
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