|06-09-2012, 11:01 PM||#1|
NorthWest Adventure Rider
Joined: Jul 2007
Location: Eastern WA State
Garmin Montana GPS Reliability Modification - Hardening How-To
We just returned from a great off road trip in NV. (Ride Report Here: CLICK HERE). On the third day of the trip one of the Montana GPS units lost satellite reception and no longer would link up to satellites. We disassembled the unit out on the trail and found that the Antenna had broke off the circuit board.
After close examination I believe this is a weak link and could happen to other units, once it happens you are stuck out on the trail without a GPS unit.
Here's a couple pictures from out on the trail working on the dead GPS unit.
The antenna is secured to the circuit board with a thin layer of clear double stick tape, It looks like the tape came un bonded (Or was never fully seated at the factory) and the weight of the antenna was hanging on the soldered post that connects the antenna to the board. With only the post supporting the weight of the antenna the post failed from the vibration and pounding the unit takes from being on the bike.
A couple pictures of the failed antenna.
We decided right there on the trail that some preventative modifications (Hardening) would be needed on our surviving Montana's so this wouldn't happen again while out on a ride.
*NOTE: This is "MY" idea of what I feel will keep this problem from happening again. If you would like to follow my lead and modify your GPS you do so at your own risk. Also NOTE that this will most certainly void your warranty so it will be your choice if you want to mod before or after your warranty expires. Myself and my riding buddies are going to go ahead and mod ours now since a dead unit out on the trail can cause real problems.
The Montana Unit ready to be Hardened.
Flip the unit over and remove the battery cover.
Note: Blue arrows show wraps of electrical tape to keep the battery firmly connected to the electrical contacts, without this you can get unsupported battery errors while using the unit on a bike. Red arrow shows a foam ear plug placed between the battery cover and the battery, this also helps keep the battery contacts solid and eliminated unsupported battery errors.
Remove the small screws that hold the two halves of the unit together. There are 8 screws in all, they are all the same length so you don't need to worry about keeping track of which screw came out of which hole.
Carefully lift the two halves apart. On the end of the gps where GARMIN is printed on the top of the unit will be a ribbon cable and a small power connection. You will only be able to lift this end of the unit slightly. We will need to disconnect the ribbon and power cables. (NOTE: It would be wise to clean the edge of the GPS before taking it apart....you can see I was in a hurry and didn't complete this step )
Using a small screw driver remove the thin piece of green tape from the ribbon cable latch. Carefully lift the tape up off the board and set it to the side to be re-used when the unit is re-assembled.
Using the small screw driver you need to unlatch the ribbon cable connector. Carefully place the screw driver under the small black latch and flip it upward, this will release the ribbon cable.
Using slight finger pressure push the ribbon cable towards the opposite end of the screen, that will pull the ribbon cable out of the terminal strip.
With the ribbon cable disconnected you can slide the top half of the GPS over slightly and get access to the power connection.
Insert your small screw driver under the wiring for the plug, right up tight against the connector. Lift up on the screw driver and the connector will pop apart, releasing the wiring.
The two halves separated. Place the screen to the side in a safe place till re-assembly.
Remove the small screws holding the printed circuit board to the bottom half of the GPS unit. There are 8 screws in all and they are all the same size and length.
NOTE: The screw at the blue arrow may be located under the white sticker (It wasn't on mine but was on my buddies as his sticker was places in a slightly different spot).
There are three final electrical connections that need to be disconnected.
Start on the two non ribbon connectors. Using the same technique with your small screw driver, place the screw driver under the wiring right up next to the connector and lift up. The connector will pop free. Do this to both bottom connections.
Now to release the last ribbon cable.
Use your screw driver and carefully lift the edge of the white release latch. Once the latch is up you can slide out the ribbon cable.
Carefully lift the circuit board out of the bottom halve and set the two halves down. They will still be connected to each other by a small wire.
And here is the Antenna unit. The Blue arrow is where the clear piece of tape is placed, between the antenna and the circuit board. The Red arrow is the soldered post that connects the antenna to the printed circuit board.
Hardening: I decided to use hot glue to reinforce the bond between the antenna and the circuit board. Hot glue is easy to apply and has a strong bond. With the hot glue in place I won't have to rely on a single piece of tape to keep the stress off the antenna post.
Hot glue won't conduct electricity but I was careful to avoid bridging any electrical connections on the printed circuit board just as a precaution.
NOTE: I was originally going to add a thin piece of sticky back foam to the back of the antenna as well as the hot glue, but when I went to re-assemble the unit it felt like the foam was putting pressure on the circuit board and causing the board to bend slightly when tightening the screws. I didn't want to take a chance so I removed the foam and just went with the hot glue. You might be able to use a thinner piece of foam than I had on hand if you don't want to use the hot glue or want both.
Carefully place the circuit board back into the lower body halve. Install the 8 screws that hold the board to the body.
Re-insert the small ribbon cable into the connector, then press the white latch down to lock in the ribbon cable. It will lightly snap into place.
Snap the bottom two connectors back in, line them up then firmly press them into place.
Carefully clean the dirt/dust off the blue silicone seal at this point.
Take the top halve of the GPS and hold the two halves together again. Start by connecting the small power connection. Line the connection up and firmly press the connector down onto the circuit board.
Insert the ribbon cable back into the connection, then press the black latch down to lock the ribbon cable into place.
Re-install the green piece of tape back over the ribbon cable latch.
Re-install the 8 screws that hold the two case halves together.
All back together and picking up satellites....even on the work bench in the garage!
NV 2012 - In Memory of the Crewmen RR: CLICK HERE
Adventure Is Out There - NV RR: CLICK HERE
Riding Through History - NV RR: CLICK HERE
And Then There Were Four - OR RR: CLICK HERE
My VW Syncro Westy Build Thread: CLICK HERE
Hodakaguy screwed with this post 06-10-2012 at 07:08 AM
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