Make a Replacement Inductor Coil Fix a Cree LED UltraOK ZS-2 Flashlight and Mod




My Cree UltraOK ZS-2 one mode flashlight that I keep on my 12 gauge shotgun stopped working the other day.

A new battery didn't work and I could hear something knocking around in it.

So I thought I would make a Instructable fixing it and trying to make it brighter.

Step 1: Take It Apart

  1. First remove the battery and the lens.
  2. Then take out the compression right and the reflector disk.
  3. Now your going to need a special tool to remove the screw. I used a old curtain rod hanger.
  4. Once that is out the PCB lifts right out. be careful not to damage the wires or any other components on the board.

I had a surface mount inductor coil fall off. Probably from 100's of recoil from my shot gun.

The wire the holds the inductor coil to the PCB broke so I need to replace it.

Step 2: Making a Replacement Inductor Coil.

The wire the holds the inductor coil to the PCB broke so I need to replace it.

Instead of wanting for a replacement to come in the mail or trying to find one in my part bins, I decided to make a replacement using the same ferrite and a new magnet wire. When taking off the old wire I thought I would see if I could get my flashlight brighter by adding a few more turns if possible.

  1. Count the turns as you take the old wire off. I had 10 turns.
  2. Now cut you new magnet wire a little long then the old wire was.I used 30 gauge magnet wire.
  3. Add you new wire to the ferrite. You want to make your turns neat and tight as possible.
  4. You want to add at lest the same number of turns as you took off. You can try more if you want I add 15 turns
  5. Once you have the new magnet wire on clean the ends. I used my soldering iron and a little solder to burn off the insulation.
  6. Bend the wire ends in to the center of the ferrite making sure you cut the wires and leaving a space so you don't short your connection and bypass the inductor coil.

Step 3: Mounting Your New Inductor Coil.

  1. I used the helping hands to hold my PCB.
  2. Clean the old solder of the connection and add some new solder.
  3. Remove the wires going to the LED. Remember where they went!
  4. I used a hot air SMD station to mount the inductor coil and reflow the whole board. You can use a soldering iron but I wouldn't recommend it. I have seen people solder SMD components with soldering irons but this is a small board and everything is tightly squeezed on there.
  5. Heat whole board evenly until the solder melts.
  6. Once the solder has melted add you inductor coil quickly and apply more heat. Once you see the solder start running to the wires remove heat and allow to cool. Be careful not to knock the PCB at all.
  7. Once cool add the LED wires back on the board.
  8. Now put it all back together and test it out.



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    9 Discussions


    2 years ago

    I had same prob with my flashlight.Also coil that broke off. I just briged on the pc board where the coil was.And flashlight worked normal with all its functions like flashing etc.


    2 years ago

    why would a flashlight need an induction coil.

    1 reply

    Reply 2 years ago

    This flashlight uses a AA battery to power a 7W LED. The circuit works like a joule thief.


    2 years ago

    This is unreal but this is EXACTLY what happend to my streamlight strion!

    It stopped working so I take it apart and the 1r0 inductor was in pieces. What a coincidence that you posted this ible at the time mine broke. I was actually going to try and scavenge an inductor from some other gadget but I will try your method, THANKS!

    3 replies

    Reply 2 years ago

    To me It looks like you might need to replace it. It looks like your ferrite broke. If thats true Me method would work. The induction would be much lower if you tried to glue it back together. You would be better off finding a salvaged part and maybe rewinding it.


    Reply 2 years ago

    You're right it is broken. I'll just look for a replacement.