Introduction
Garmin's latest forerunner revision provide a good feature set to compete with other fitness watches.
In following other manufacturers, a glued front technique has now been adopted by Garmin.
The unit featured here developed a fault, in under two years of active use.
Support from Garmin quoted a £100 fee to replace the device out of warranty (approximately a third of the cost of the device).
Instead of paying this, let's dive into a teardown and share some information instead.
What you need
-
-
The strapless 735xt, the straps are secured by two T6 screws on each side.
-
-
-
The front is glued
-
Use an iFixit Spuder to prise around the glue. It's not necessary to use a heat gun here.
-
-
-
Once the screen moves, carefully remove the ribbon connector and the screen.
-
-
-
-
Two T6 screws hold the mainboard to the body.
-
The main board will move from where the Spuder is inserted.
-
Remove the green protective tape and disconnect the second ribbon cable before proceeding.
-
-
-
The unit will now be disassembled
-
Unplug the battery by lifting up the connector from the bottom.
-
Further disassembly and analysis to follow...
-
-
-
GNSS receiver looks like MediaTek MT3333 with external amplifier+filter+chip antenna. And ARM7 CPU.
-
The watch has at least 3 Cortex-M4 microcontrollers, not counting Ant+ or GNSS chips! Microchip ATSAMG51, ATSAMG53 and MAX32360
-
nRF51422 contains ANT+ and Bluetooth LE functionality. And Cortex-M0 CPU to run these.
-
11 Comments
how to glue back?
I’ve not attempted to re-assemble yet. The glue was held around the LCD display.
These units are identical to the manufacturing process of more popular units such as the 235. So someone might of given a guide to putting those back together.
The core thing to keep in mind is that a decent seal is going to be required to avoid any water damage.
When you have a water damaged Forerunner 735, it is probably not necessary to take the 735 completely apart, to repair it. Just take away the front, and then use a air pressure spray to blow out the water. I did not test it, but here is an instruction, which shows that this worked for the Vivoactive HR:
https://www.youtube.com/watch?v=rAKbZ_Tx...
Peter Gamma
See also discussion here:
Correction: It was not air pressure spray but CRC electronic cleaner Dean Stucker used in his youtube video which shows how to repair a Vivoactive HR. Difficult to find here in Europe. Alternatives?
