A few weeks back, we announced our decision to recall our v1.1 balenaFins due to a USB issue at high temperatures, along with an in-depth explanation of the issue.
We offer free repair for any customer that has purchased a v1.1 balenaFin, and many of our customers have already gone through the process. But since we're also tinkerers ourselves, there's no denying the thrill of being able to fix our own stuff. We created this guide to make that process as easy as possible.
Before we begin
Attempting to perform the fix in any other way (including the steps detailed below) will result in a void of the balenaFin warranty. This process should only be performed by someone with highly developed soldering skills.
- 2 x RES SMD 1K OHM 1% 1/16W 0402 ±100ppm/°C (i.e. RC0402FR-071KL).
- Soldering station or hand solder iron with fine solder tip*
- Environmental chamber for heat testing. While this is not mandatory, it is the only way to verify that the balenaFin is working correctly at high temperatures.
*A soldering tweezer is recommended for desoldering the tiny resistors.
First, make sure to remove everything connected to the balenaFin. This includes the power cable, complute module, coin-cell battery and any other peripherals.
Now it's time to desolder the original 47K resistors that were causing the issue. The picture below highlights the position of the resistors to be desoldered.
Once both resistors have been removed, solder the replacement (1KOhm) resistors in their place.
Finally, in order to verify that the process has been done correctly, we need to perform two tests:
- Follow the steps in this guide to flash a new image to the balenaFin. If the image can be correctly flashed, the first test has been successful. Otherwise, double-check that the replacement resistors have been properly soldered.
- Test the fin at high ambient temperature as follows:
- Connect the balenaFin to the network via the Ethernet (RJ45) port or connect a USB peripheral (ie. USB flash drive) to one of the USB ports.
- Power up the board and verify that the ethernet connection (or USB peripheral) works as expected.
- Put the balenaFin inside a temperature-controlled environment.
- Slowly (2°C/minute) raise the ambient temperature to 60°C (122°F).
- Verify that the connection (or USB peripheral) continues to work normally.