In this guide we will show you how to repair Q1 in your ODROID-N2.

Discrete Load Switch Schematic with FTK3407

Causes of Q1 Transistor Failure

Over-currents even for a short duration can cause progressive damage to a MOSFET, often with little noticeable temperature rise before failure. MOSFETs often carry a high peak-current rating, but these typically assume peak currents only lasting 300 ┬Ásec or so. may be damaged.

The causes of Q1 Failure are generally built-in current limiting circuits in integrated power switches to prevent the load SW from being destroyed during over-currents. In case of discrete load SW, the current limiting circuit is not built in, so the P-CH FET FTK3407 is damaged due to over-currents as shown above.

  • When the eMMC is mounted to reverse, over-current flows to VCC3V3 due to the FLASH_1V8 node short circuit to GND.
  • GPIO connection error or GPIO short-circuit on the 40pin IO port.

Failure to function due to failure

As shown below, the load switch does not supply the VCC3V3 node due to destruction, so the power supply to it is not supplied, so booting to the eMMC, USB, Ethernet and IO pin etc. does not work.

- You can also replace AO3407A alternatively since FTK3470 is not easy to get.
- Make sure let components R44, R45, and C147 near Q1 be. It could go flying by your soldering iron.


Step 1. Mostly you could see the Q1 damaged by appearance as shown the image.


Step 2. To detach Q1 out easier, you should add solder a little on the pad of Q1.


Step 3. If you have a spare soldering iron, use it as shown the image.
If you don't have a spare soldering iron, it would be harder than using two soldering iron, but you could be melted solder on the three pad at the same time and then pull it out.


Step 4. Remove the rest solder on the pad. Use it, If you had a solder wick.


Step 5. Use it tweezers and do soldering with new Q1.

Conclusion

We hope that this guide will help you to repair your ODROID-N2.

Now that your USB, ethernet, Expansion Connector 3.3V power and eMMC booting works perfectly after replace Q1 P-CH FET.

Reference