Back in January (2007) started a new 10,000 FON Giveaway. Fon routers are popularly used around Starbucks and other public places. They send out two access points, one secured for you to use, and another unsecured for public use. The two signals are completely separated and you can’t cross between them. When the public use your public signal they are redirected to your Fon user page. From there they can pay a small fee to use your internet. And you the owner of the fon actually make money with it. Other people hack the fon and install DD-WRT. I am planning on modding mine quite a bit, but since I got mine free and that would morally be wrong, I am going to buy another fon at actual price. The mods include things like adding a serial cable, adding a second antenna, adding fans and extra cooling, and making it a web server.

After three weeks I got my Fon router in the mail

Fon Packaging

I removed the dinky little heatsink fan from the inside of the Fon.

Heatsink Removed

I used the rest of the heatsink from my Inverter Project to use as an upgrade from the old one. I had to trim it down quite a bit to get it to fit. Here it is compared to the old one.

Larger Heatsink

I had to trim down the fins also to get the cover to fit back on. They were a lot tall as you can see here where I compared the trimmed heatsink to the part I cut off earlier.

Heatsink Cutdown

I have always wondered about using JB Weld as a thermal paste/glue. So I decided to give it a shot on this project. I am very pleased with the results.

JB Weld Thermal Paste

I also trimmed the tabs off of the old heatsink, applied JB Weld to it and put it on the chip that I noticed always was scorching hot. Everything fits in the case and I might later enlarge the vent holes next to both heatsinks for better airflow.

Heatsinks Installed

If you go here then you can get yourself a DS275 free! Just request it as a sample and they will mail it to you free. The schematics for this Serial to TTL converter is. Please don't abuse this offer. I have bought many other items from them and I like their prices and selection.


Thank you PwnStar for the old and new diagram.

This is an extremely easy circuit and the main part you can get free. The only thing better would be if you could get the whole unit free and already assembled. I will add pics when I get my free one and my actually paid for serial to ttl converter.

I purchased two more Fon’s for whatever reason. Truthfully I still don’t know exactly what I am going to do with them. Some ideas include:

  • Universal Wireless Repeater

  • Wireless Receiver

  • Wireless Robot Controller

  • Wireless AC Controller

  • Web Host

I still do not know what all I am going to do with them, but I am that much more excited about having them.


I know that the first thing that I have to do is to secure my investment. Since they are renowned for overheating I will have to figure out a way to cool them better. Here is the internals of the Fon router unaltered.

UnAltered Fonera

To take the heat sink off you have to either desolder or just cut the metal tabs that go through the pcb board. I choose the cutting method. The red circles are the tabs.

Heatsink Tabs

Now that the heat sink is off I can take off the metal cover under it. I do not understand how the designers can expect the heat to efficiently be transferred from the chip through the thick thermal pad, through the metal cover, through another thick thermal pad, and finally into the heatsink. I will eliminate most of those by only using one of the existing thermal pads between the heatsink and the chip.

Shield Removed

Heatsink to chip size comparison picture.


With the extra pad and metal case gone, the metal tabs on the heat sink can now go through the pcb board and still stick out plenty enough to be soldered back to the board.

Reattached Heatsink

Everything back in place and the new heatsink arrangement installed.

Modified Fonera

While repeating the above steps on the other router I managed to rip off one of the tiny resistors… (The little speck on the white paper). But even with my shaky hands I was able to solder it back on with no fuss.


Specs So Far:

  • I don’t know how hot the original setup ran but I would guess at least 160-180 F. on average with the lid on.
  • Version 1 heat sink mod (large heatsink) = Chip 110deg F, Ram 110deg F.
  • Version 2 heat sink mod (metal removal) = Chip 145deg F, Ram 125deg F.

the difference that the larger heatsink made is tremendous. If I took off the metal cover and installed it directly to the chip, then it would function quite a bit better. I am happy with the results and will leave it the same unless it breaks.

I decided to try and add some more vents to my original Fon. I decided that the best place is right above the main heatsink. This way the air will be drawn in from the sides and out through the top vents. I first made a border in which I knew that I couldn’t cut outside of. The border is the size of the heatsink except for the corner that has the fon logo on top.

Vent Slits

Here is the view from the top. I made the cuts with a dremmel and a cutting wheel at low rpm’s. I choose a low speed so that the plastic wouldn’t melt as much or burn. I am very happy with the results and I am thinking about adding more vents above the ram heatsink and repeating the process on the other two Fons.

Vent Slits Top

I decided to attempt something similar with the other two routers. I mapped out the area to cut and I decided to make three cuts. On the last router I noticed a difference between the ends of the cut due to the direction in which the dremmel rotated. So I thought I might go over each cut on this one twice. Once from either direction. I didn’t realize the angle that I was cutting at was quite off 90deg. So it didn’t turn out how I planned but it still works.

Vent Slits

On the third router I decided to make a total of five cuts; Three large and two small. I learned from my last attempt to only cut from one direction and I am very happy how this one turned out. Since the heat sinks are smaller I made smaller vents to lessen the risk of a screw-up.

Vent Slits

Here are all three routers next to each other. The middle one is the one that I cut from two directions and you can tell that the vent is wider. I don’t care for how it turned out but like I said, It works.

Vent Comparisons

I ordered a usb to ttl converter so that I could plug it into any computer. After reading around on the internet I saw that only two wires are needed in the communication. Seeing as how I have multiple Fon’s I knew that I wanted to be able to use the cable on all of them. So I came up with the idea of using an audio jack to connect the Fon to the cable. Here is the Fon with audio jack installed.

Fonera Audio Serial Jack

The audio jack is very slimline and not noticeable. It was very easy to drill a hole and install. I would recommend this for anybody else attempting this project.

Audio Serial Jack