What is inside a Nokia charging pad ?

[kultakala]

Hi,

I will not call this a teardown, although it probably is kind of one.

A few years ago i got my first mobile/cell phone with wireless charging.
It was a nokia phone and when they brought out the new chargers with notification led light i bought a few of them.
There were three colors, white, green and orange...  i went for the orange ones.
The model number is DT-903.
The Microsoft DT-904 is the successor, its available only in white at this time and i guess beside the microsoft logo its identical (?).

Unfortunately one of my chargers stopped working. When charging it stops after a few minutes and starts blinking only.
Maybe it would be possible to fix it, but...  i decided to tear it down and have a look inside :-)

Many chargers are advertised that they have 2 or 3 coils...  the DT-903 charges very well.
You can put the phone where you want, it always charged with very good power.
When measuring the input to a usb charger it shows about 9 to 10 Watts.

So, here are the pictures:

First from outside...




With light while charging my Microsoft Lumia 950 XL




Two luminated devices




Caseless with light




Upper side...  and it has 5 coils !




PCB side...




I uploaded a high res photo but its only visible in smaller resolution...  Hmmm...