Within a few weeks of buying my Garmin FR 305 I managed to crash on my bike with the only injury being to my pride and the LCD of my watch.

This is what the watch looked like after my smash fest:

The watch still beeped, and it synced to the computer just fine.  I did have a weird issue with the file for that ride, some data was missing.  The miles were right but the map data was off.  I’m not sure what happened there.


At any rate, my options were limited.  I didn’t want to buy another watch, but even in the short time that I owned this watch it had really grown on me.  I decided to try to fix it.  I did a quick search for fixing the watch, and found a number of people who spoke generally about replacing the battery.  The most important piece of information I found was that the watch had to simply be pried open.  Apparently it is sealed with some sort of glue.

DISCLAIMER: Opening the watch may ruin it permanently, and it will definitely void the warranty.  I figured that I would take the chance because it was broken anyway, but if you aren’t comfortable cracking open electronics you shouldn’t try this at home. 

I tried a number of things but ending up using a watch back opening tool from a watch repair kit that I have.  It looks something like this one:

Image from www.esslinger.com


It is a bit sharper than a butter knife, without the serrations, but more dull than a regular knife.  You can pry anywhere along the seam around the middle of the case, but I found that it was really hard to get open until I put the knife near the lower watch strap here:

Note the screwdriver is there only to point out the location, a screwdriver will likely damage the plastic of the case.

The watch case gave a little cracking sound as the glue seal broke, and then it was just a matter of carefully pulling the two pieces apart with the watch knife.  Once it came lose it looked like this:

The blue arrow points to the GPS PCB, the yellow arrow is pointing to the main PCB (circuit board) which includes the memory, and the LCD controller, the LCD is under the main PCB board.  The red arrow is pointing to the battery, and the green arrows are pointing to the connectors that connect the battery terminals to the PCB.  As you can see this is just pressure fit.

The top piece is now completely disconnected from the watch strap which is attached to the bottom of the watch case, which in turn holds the battery.

With the top piece off we need to get to the LCD screen which is under the main PCB.  There is one screw that needs to be removed at the top of the board by the copper terminals.

Once that screw has been removed the PCB will pop off along with the LCD screen.  The LCD screen isn’t affixed to the PCB so it will just pop off and reveal a flexible cable that connects the LCD to the main PCB.  Be careful not to move the LCD too much or you run the risk of disconnecting the cable that connects the main PCB to the GPS PCB (more on that later)

The LCD screen is the white plastic thing at the blue arrow.  The flexible cable connects to the PCB at the connecter (red arrow).  The tape holds the locking clip on the connector down.  Peel off the tape, and with a small flat head screw driver you should be able to carefully pry up the clip and release the cable.  Once the cable is released the LCD screen will come right out.

Now you just need to put the new LCD screen in by attaching the cable, and slipping the clip on the connector down.  Then , if you salvaged the tape put that back over the connector.  If you didn’t salvage the tape I wouldn’t recommend using scotch tape because I’m not sure what will happen in terms of static electricity from the tape.  If you have Kapton tape (which is safe to use on electronics) I would use that, but otherwise the clip should be OK without the tape.  Be careful to make sure that the cable is oriented the same way as before.  You can do that by laying out the new LCD screen prior to disconnecting the old one.  In order for it all to fit together without twisting the cable there is really only one way to do it, so I wouldn’t worry too much.

Now clip the LCD screen back onto the PCB.  There are tabs on the LCD that fit onto the PCB so that it is all held on securely.  Put the PCB back down and screw in the little screw.

With that, the hard part is done.  Press the two halves back together and, while holding the two halves together tightly, hit the power button.  If all went well you should get the forerunner splash screen followed by the satellite signal acquisition bar like this:

If the bar doesn’t move at all after a while (try going outside or near a window) you may have accidentally disconnected the cable between the main PCB and the GPS.  Mine was working fine, but then I decided to take it apart again to take these pictures.  The cable got disconnect from the GPS PCB.  You can reconnect it the same way as the LCD was connected.The connector is at the red arrow above.  It is also possible that the other end of the cable got disconnected from the back of the main PCB.  You can see that connection next to the LCD connector two pictures up from this one.

As I said above, the two parts of the watch are pressure fit together and come from the factory attached with glue.  If the two pieces aren’t fully pressed together the battery contacts will lose connection and the watch will shut off.  In my research I found a tip from this site which suggested using clear RTV silicone to glue the watch shut, and to hold it together with electrical tape.  I used the silicone, which you can buy at an automotive store, and electrical tape.  I ran the silicone around the edge of the top half and squeezed it together.  With a paper towel I wiped off the excess.  I wrapped the watch in a clean paper towel and tightly wrapped electrical tape around it.  Electrical tape works best when it is stretched.  You can pull it around the watch, and at every half turn pull the tape until it stretches, and with the tension on the tape complete another half wrap.  Continue that until the watch is completely wrapped like this:

This looks bananas (Yellow tape optional)


I used the paper towel just to keep any residue from the tape off of the watch.  Depending on how long it is applied it may leave some stickiness behind.  By using a paper towel any residue will stick to the towel instead of the watch.  The paper towel also has the added benefit of absorbing any excess silicone, and providing some air pockets to cure the silicone.

After 24 hours I took off the tape and went for a run.  It worked great.

I purchased the LCD on ebay as part of a broken watch.  I did note that they had some plain LCD’s for sale too (without the rest of the watch) for around the same price ($35).  At the time I wasn’t sure how the LCD was attached, I thought it might have been soldered, so I figured having the entire parts set was safer.  Now that I know how easy it is to replace the LCD I would say buying the LCD alone should suffice.

That’s that.  With any luck this should last me a long time.