I have an Olimex A20-OLinuXino-MICRO board that I use for running embedded Linux (armbian). It is a very nice board with an Allwinner A20 dual core ARM processor, 1GB RAM and a lot of connections. The features I like the most are the SATA connection and the integrated LiPo battery charger. It is like a uninterruptible power supply on board!
Unfortunately both the 5V connection for the SATA drive and the LiPo battery connection are close to each other and they have exactly the same female JST connector. You can probably guess what went wrong: I connected the LiPo battery to the 5V SATA connector and I plugged the 5V cable from the SATA drive into the LiPo connection on the PCB 😮
Luckily all Olimex hardware is open source and that is yet another reason I love this Bulgarian company! On the A20-OLinuXino-MICRO wiki page you can find a lot of information, including a link to their github repository that also includes the full schematic!
So let’s digg into the documentation and get this thing repaired…
Luckily, plugging in the 5V for the SATA drive into the LiPo battery connection did not damage the drive, nor did it damage the pretty complicated AXP209 power management chip on the Olimex board. Alas, the 5V SATA power connection was dead, it did not provide the 5V for the drive 🙁
The schematic for my Rev.E board show that the SATA 5V is switched by an MOSFET with part number FET4.
I was able to temporary restore the 5V by bridging jumper 5V_E_SATA with a bit of solder:
It was pretty clear that FET4 (the IRLML6402) was defective, and to fix that permanently, it needed replacing. After a few days, I received ten replacement FETs from eBay (US $2) and it was time for my first SMD repair job:
Removing FET4 was pretty easy. I then cleaned up the solder pads with solder wick and flux.
It was not perfect, but the pads were flat enough to receive the new FET.
After that, the A20-OLinuXino-MICRO worked perfectly like before.