The PT EOS is a reliable and durable headlamp with many great features. However there are a few areas where it can be improved upon, namely the optic and the LED.
The PT EOS produces a beam of light by channeling the output of the LED through an optic. This is adequate for most users, however the produced beam lacks sidespill. In the case of a headlamp sidespill is especially useful as it allows you to light up a larger area for close up work. By removing the optic in favor of a reflector we are able to produce a nice smooth beam with lots of sidespill while still retaining a good central hotspot.
The other item we can improve upon is the LED. The PT EOS comes with a Luxeon I LED which produces nice bright output, especially for a headlamp. However this LED is somewhat outdated and more recent LEDs can now produce twice the amount of lumens at the same current draw. This is quite an improvement.
By modifying these two things we are able to make a great headlamp even better. The modification is not difficult and the results are spectacular; well worth the effort put into it.
Tools required:
-Screwdriver
-Drill with small drill bit
-Soldering Iron & Solder
-Scissors
-Round file
-Superglue(optional)
-Penny(optional)
-Dremel(optional)
Materials required:
-Princeton Tec EOS Headlamp (Available from REI, Walmart, and many online sources)
-Seoul P4 U-Bin LED on star (Available from Dealextreme at
http://www.dealextreme.com/details.dx/sku.1445 or PhotonFanatic on the CPF forums)
-Fenix reflector for LxT/LxP/LxS series lights (Available from
http://fenix-store.com/product_info.php?products_id=154)
***See update at bottom of thread regarding Fenix reflector availability.
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Procedure:
The first step is gaining access to the circuit board & LED assembly.
Using a screwdriver, loosen the screw on the back of the headlamp to gain access to the battery compartment. Remove the batteries.
You will now need to seperate the battery holder from the headlamp housing.
The battery holder is secured to the housing using two rivets, one on each side. These are visible once you have removed the batteries.
Using a drill with a small drill bit, drill into each rivet until you are able to pull the battery holder from the headlamp by using your fingers.
In the following picture I have drilled out the rivets and am seperating the battery holder from the headlamp:
After you have the battery holder removed, you will see that on the other side of it is mounted the circuit board and LED/optic assembly:
The optic and "optic holder" can be removed using only your hands to allow access to the LED:
The "star" that the LED is mounted on seems to be superglued to the PCB, but I was able to seperate it fairly easily by just pulling up on it with my fingers:
Now we have access to everything and can begin our modifications.
To remove the old LED you must de-solder the red and black wires from the + and - contacts on the star. You can also take the easy route and just cut the wires at the star.
Once the old star is detached, set it aside. It should still be a good and functional LED and you never know if you may use it on a project some day.
Now take your Seoul LED and solder the red(+) and black(+) wires to the contacts marked + and - respectively on the star. Pay special attention to the two notches on the bottom of the optic holder to assure that you are soldering the wires to the star in such a way that they will align with these notches when the optic holder is installed. If you do not do this correctly the wires will keep the optic holder from being able to be flush with the star.
Once you have finished it will look like this:
Now we are ready to begin installing our new reflector.
Basically the Fenix reflector will fit perfectly and securely into the stock optic holder with minimal changes. The first modification you need to make for the reflector to drop in is to file or dremel down the vertical ridges inside the optic holder. You will also want to remove the plastic that connects from side to side across the bottom of the optic holder. This will allow the new reflector will come down all the way on top of the LED and focus properly. I used a pair of scissors for this task. Pay special attention here and make sure it is not possible for your reflector to touch the solder blobs on the star, causing it to short. This will only be an issue if your solder blobs are too tall.
After you have the reflector inside the optic holder you are ready to secure everything together, but there is one more issue to address.
In stock form the PT EOS has a thermal sensor behind the star that detects when the LED is running too hot and cuts down the current to keep it from overheating. Once you install the Seoul star you are left with a gap between the star and the thermal sensor unless you replace the blob that is on the bottom of the original star.
Keep in mind the Seoul LED is more efficient and runs much cooler than the Luxeon III in the headlamp originally. I did not attempt to connect the star to the thermal sensor and I have run it for extended periods of time with no ill effects. It is quite possible that with this new cooler-running LED and relatively low current output of the EOS driver(~300ma on high) there is no additional heat management necessary.
However, it would definitely not cause any harm to use some sort of heat transfer material on the bottom of the new star thus connecting it to the thermal sensor in the same fashion as the stock star. I have also heard of people sanding down and gluing pennies to the back of the star to act as sort of a heatsink, which I would recommend as a simple way to help dissipate some excess heat.
We now move on to assembly...
Install the optic holder with optic over the LED:
Top view:
Now simply put the circuit board/battery assembly back into the headlamp housing. If you drilled out the rivets a little too far, it may be a good idea to put a drop of super glue in each rivet to make sure everything stays secure.
View from the front with everything installed:
Now install the batteries and hit the power button! You should be presented with something like this:
A nice, bright, smooth beam with lots of spill... Enjoy!
-tibim
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*********** UPDATE 11/2/07 ************
The Fenix reflectors originally used in this mod are no longer available. See the following post for more information:
http://www.candlepowerforums.com/vb/...&postcount=159
PT EOS Seoul & Reflector Mod Writeup
Re: PT EOS Seoul & Reflector Mod
Just what I was looking for.
Linear Mode
