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 :shog)
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!
Great thread and pics. I've added it to the forum sticky.
Sorry you had problems. Never heard of that happening before, but a great way to keep it from happening at all.
Thanks for sharing!
Very nice howto. Silicone is traditionally used in these types of applications (for example, stabilizing tall through-hole capacitors against vibration) and should work as well, though it won't cure right away. It is disappointing that this weak link slipped by the shake and bake qualification, but as you say it could be an isolated case.
Great heads-up & fix for those of us with a Montana that is Off Warranty.
I just finished doing mine and the only tricky part was getting that first screen ribbon to slip back into the mount so it could be locked in.
I also used silicone glue and let it dry before putting things back together.
Sounds like what happened to mine, there is a slight rattle inside. It was the first time on the bike mount, hadn't even been off-road yet. Hopefully there is no issues with Garmin warranty.
After the hardening surgery and recovery............ feedback on my Montana 650.
The 650 is still going strong after the fix....................no issues and I use it a lot! :D
Glad I did it.
Hodakaguy, you rock! :thumb
Great how to and very easy to follow. Thanks
thanks for posting that. Think I'll wait until my warranty is done.
Since my warranty just expired, I performed this using clear silicone. A couple things I found-
1st- This stuff is TINY! The screws require a T6 torx bit- that is really small. I needed a magnifier I use for reading jet size numbers.
B- When I put it together, the display was very washed-out and rippled. I looked over the pictures again, and realized I missed putting the green tape back over the ribbon connector. After fixing that, everything was fine.
Apparently the tape is a necessary insulator. Good to know.
I'm getting a white screen on power-up. Pushing power button still beeps properly and powers down (two beeps), suggesting the unit may be functioning fine, problem affects only the display. Has anyone seen this before? (Re-seating the ZIF ribbon does not solve it.)
This is a rather old thread, but being an electronic tech for 35yrs I'd advise against using hot glue or any other glue to glue parts to the board. 60 million or more TVs built over the years they would glue parts to the board and this was always the first place to look when problems reared their ugly head. Glue expands/contacts with temp and it's amazing the damage it will do, and it will every time. Better to use two sided tape if it can be made to work in the situation.
Chinese love glue and let me tell you if they thought glue could be used here they would have gooped it on 2" thick. Thankfully and hopefully lessons have been learned after all these years, don't glue parts to the board!
The unit comes manufactured with double-sided tape, and a big solder join in the center under the antenna. Despite that, others and I experienced loss of satellite reception due to that solder joint failing due to long term exposure to vibration. The OEM tape and solder are not adequate. Garmin offers Montana as a handheld trail unit, specifically does not offer it among their motorcycle-suitable devices. Does "better tape" exist? You'd have to re-solder the antenna to get it off, replace the tape, solder it back on... I will always carry the external antenna as a backup. This is all a lot of hassle for a GPS unit...
So far my repair with the hot glue has held up great, the antenna is still held in place with the factory tape and has glue around the edges. If I was to do it again I would probably use silicone instead of hot glue. Either way it's still going strong :-).
It would be very interesting to see the inside of one and compare it to the inside of a standard Montana, to see if any hardening is apparent.
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