Fixing water-damaged Mi Band 6 [repair overview]
So yeah, I got into the Black Sea with my band on the wrist…
I was very confident that the device is waterproof, so it took me a while to realize that it got damaged. Initially, only the touchscreen failed, so I tried cleaning it, thinking that the water left some residue around. Trying to understand what’s happening, I woke the band multiple times, which only worsen the situation.
Another thing is that I was at the vacation, and I did not have any tools on me to disasseble the band. It had to lay around and dry on it’s own until I returned home.
So the corrosion went pretty severe because of my profane actions.
Why the damage?
The device consists of a plastic shell with the screen glued into it - simular to how modern smartphones are built. With time and mechanical damage the glue can loosen and create a leak. In most extreme cases the screen can start to peel off.
The connector and the display cable are damaged because I tried to wake the band with the water still inside!
Water acts like an electrolyte, allowing the electricity to pass through, essentially driving electrolysis and causing trace oxydation and eventual deterioration.
Display consumes a lot of power, and large amounts of current accelerate the process. In most severe cases, the trace can be destroyed completely, leaving no way for the electricity to travel and ultimately killing the device.
There are excellent videos by Louis Rossmann that show exactly how this happens.
Repair
In my case both the connector and the display required replacement. Even though the display is probably still good, it’s connective part is gone. I’m not familiar with any technique that can help repair it.
The display connector is called FH58-31S-0.2SHW, it’s a 31-pin FPC connector from Hirose. I bought a couple from Farnell.
The vibration motor is located just underneath the connector. Applying heat to that area seems ok - at least it does not damage it or melt the plastic. However it’s possible for the flux to get inside. In my case it did - so the motor works much worse now, and sometimes squeak. I think more thorough cleaning is required, if even possible.
Is it worth it?
Probably no. The band is so cheap it’s not worth repairing it at all. The screen was around 11$ and a couple of connectors with delivery was around 10$. Older-gen Band 7 is probably like 35$ at the moment, and the newest-gen Mi Band 8 should be around 50$.
There are risks of breaking stuff. Sealing the device up like it was from the factory is probably not possible (at the other hand their glue is not good either).
Battery is probably damaged from being discharged for a while.
Still, I didn’t want to throw the old one away…