How to Disassemble an Edge



Edge® 705
The new Garmin 705 Cycling GPS
Bet that headline got you excited - unfortunately this is only an incremental upgrade, and even that’s stretching things a bit. The latest model of the Edge 705 comes in the Garmin/Chipotle team colors and includes all the same color mapping features as the regular 705.

One new item from Garmin is the US Topo 24k map software series that gives you even more topographic detail for US terrain. The software even enables 3D views of terrain on certain GPS units like the Colorado and Oregon - a first for Garmin GPS units. Hopefully we’ll see this trickle down to the smaller cycling GPS line in the coming years…

Edge 705 Suggested Retail Price: $ 549.99 USD

Edge® 305
Take your ride to the next level with Edge 305, Garmin's GPS-enabled personal trainer and cycle computer. With a wireless heart rate monitor and speed/cadence sensor, Edge 305 will help you achieve your personal best.

Rugged, lightweight Edge attaches easily to the stem or handlebars of your bike with the included bike mount. Just turn it on, acquire GPS satellites and go.
Edge 305 automatically measures your speed, distance, time, calories burned, altitude, climb and descent, and records this data for your review. For extra-precise climb and descent data, Edge 305 also incorporates a barometric altimeter to pinpoint changes in elevation.


Rugged, lightweight Edge 205 attaches easily to the stem or handlebars of your bike with the included bike mount. It’s just like the Edge 305 but it can‘t track your heart rate, cadence, climb and descent.

Edge® 305 Suggested Retail Price: $ 379.99 USD
Edge® 205 Suggested Retail Price: $ 274.99 USD

HY Mini Wind Turbine.

As if carrying your iPhone on the MTB trail wasn’t geeky enough, now you can CHARGE your iPhone on the trail using only the wind rushing over your handlebars:
Meet the HY Mini Wind Turbine. Just attach the HY Mini to your bike and as long as your speed relative to the wind is over 19mph for 20 minutes you’ll get enough juice to power your iPod for 30 minutes.
You’ll get power at speeds as slow as 9mph but I’m guessing that might be a losing proposition (20 minutes of pedaling just to get 10 minutes of iPod just doesn’t seem so great).
I know I take a fair amount of tech out on the mountain bike trail but I’m generally pretty careful to make sure everything (GPS, phone, camera) is charged up before I head out.
The HY Mini could really come in handy in an emergency though - ya know, just in case you lose the trail and that 4 hour epic ride becomes an overnighter
Retails $69.95
Disassembling an Edge:
The rubber over the switches is an overmould on the grey front cover.
An overmould is a created using a two step moulding process.
The grey front cover is injection moulded first.The rubber switch cover is then moulded on top of the grey front cover in a second shot.
The end result is that the switch cover is permanently attached to the grey front cover.
Any attempt to seperate the two parts will damage it beyond repair.
However, the black rear cover is not attached to the rubber switch cover at all.
If you push the rubber towards the top cover, you can actually see a gap open up between the two.
Jam your thumbnail into the gap between the switch rubber overmould and the black rear cover.
Slide your thumbnail along the gap so that it goes around all the way around the Edge a few times.
This action will lift the rear cover off the Edge.
You don't really need to push or pull on the back to get the Edge apart.
The rubber pushing against your thumbnail will help to push the back cover off.
Your thumbnail will cut through some of the adhesive and you should be able to hear the adhesive tearing after you've gone around a few times.
What's Inside?Well, a bunch of electronic parts. A single PCB goes with the top cover which has the switches, the GPS, and the display.The back cover has the battery, the beeper, the air pressure sensor, and the USB connector.
The connection between the two halves is done using a set of spring loaded contacts.
Any corrosion due to moisture could cause loss of contact and may explain issues with sudden power loss.
Anyways, there it is, if your so inclined.
Now I wouldn't recommend doing this unless your REAL comfortable with taking things apart.
There really isn't much point anyway.
There's only about 3 failures you could realistically diagnose and repair in this thing.
1) Dead battery
2) Broken switch (This is what I had, the cover popped off a switch!)
3) Intermittent contact between halves.Forget about figuring out which chip is bad and changing it at home.
Service is a board swap.Reassembly?
Glue the two halve back together using rubber cement.

I think the spring contacts will always be a problem. Didn't Garmin realize that bicycles hit bumps? I moved the battery wires to the main board. No more warranty for me, I guess. But why would I expect to get one that works right when this is obviously a major design flaw?
The black wire was tacked to a small plated pad and came loose after a month. I ended up moving the black wire to the other side of the main board, above the display, to what I assume is the GPS antenna. It's white and round and there's a big solder blob in the center. I attached the black wire to the blob and it's been working fine.
So now, more than 2 months and 1000 miles with no shutdowns, except when the black wire came loose last month. I had my doubts about tacking to that tiny pad but it was the closest point. Now if I could only remember to charge the thing before I go.
 
Ok, I wanted to quote myself just to share one thing: I later found out what the 8th pin/spring is supposed to do. It is part of the USB/Recharge connector interface. In fact, I found out that something wasn't working as expected only when I tried to download the data gathered during today's ride and the 305 didn't respond at all. To my extreme disappointment, I found out that the unit wasn't neither recharging nor transferring data.
I quickly remembered the spring connector that I almost broke yesterday (although USB was working correctly after the "open chest surgery") and then decided to re-open the edge to check the situation. As I could state, with a look of horror on my face, today's ride vibrations finished the job I've started yesterday. Shame on me... The upper part of the spring simply separated from the rest at the weak point I inadvertently created.
I was already organizing my next trip to a local bike shop, in order to buy a replacement unit, when a new idea struck me. The approach was clearly the latest attempt to "repair" the unit: i tried to bend the lower (the remaining) part of the spring on itself. The idea was to reach a sufficient height, and the right slope grade, to reach the PCB and establish a reliable contact with the brain of the unit. I had nothing to lose... so i simply tried, and it worked. So, if you are as careless, reckless, too strong and not inclined to manual tasks as me do not despair!!! Try to follow my path (or don't even try to repair the unit in the first place).
I Just hope that my workaround will last and continue to function properly in the future.
See attached images as an example.
I've talked with the local Garmin people, you can't change the casing
Garmin make some merchandising units - they use the outer case with a hollow interior with a printed display card of info under the screen and actual buttons inside to give the correct feel.? The Edge 305 "dummy case" is part number M01-00023-00 and the dealer cost is about US$5.? The last lot I got was a couple of years ago - they may not be available now.? A dummy case would make an original replacement case.? The Forerunner 305 dummy case is part number M01-60183-00.

Don't cut the mounting slot area on the back of the case off as here is nothing underneath - the photo shows the inside of a dummy case:

With dummy circuit board which has switched attached.? The Lap and Start / Stop buttons are on the other side of the board:

2 comments:

Anonymous said...

Thanks for info.. Have some questions, did you take the pic of 705 during lamp of 705 is on? because my's get suddenly dark and did you find any trimpot as you open 705 for contrast of screen

Scot O'shea said...

Thanks for taking the time to discuss this, I feel strongly about it and love learning more on this topic. If possible, as you gain expertise, would you mind updating your blog with more information? It is extremely helpful for me.