FED failures can be traced to IR sensor and circuit board issues, which can be remediated with an isopropyl wash.
Does your FED look like this?
It should look like this…
Cleaning Protocol
What you might need:
- Compressed Air
- Kim Wipes
- Isopropyl (≥70%)
- Cotton swabs
- Non-metallic tool for removing RTC battery
- Short-cut (stiff) nylon brush
- [Optional] brash brush
Disassemble the FED as shown (RTC battery, microcontroller, micro-SD card). You can now effectively spray the entire circuit board with isopropyl. Use the nylon brush in a circular motion on all surfaces and components. Continue to wash debris away with isopropyl. Use Kim wipes to dry the boards or wick away debris.
Don’t hesitate to spray isopropyl directed into the IR sensors. Use the brush and cotton swaps to continue cleaning the debris.
**When wet cleaning is done, use compressed air to dry everything. Spray air in all the crevices. You may want to perform another wash after this, as the air will expose more debris.**
Perform the same steps on the microcontroller board.
INSPECT INSPECT INSPECT
These are all photos from an FED that were used a lot. Each photo represents a failure mode.
Scratched/dirty IR beam lens:
In some extreme-wear cases, the IR module may need to be replaced. These are difficult to desolder without the right equipment. Reach out if you need help!
We have tried to coat (and infill) these with optically clear epoxy, but it distorted the beam to a non-working state. You can also diagnose these modules by probing the pin voltages using a digital multimeter. See Sharp GP1A57HRJ00F on DigiKey for the datasheet.
Debris or flux residual over integrated circuits or pins can attract dust/moisture and bridge pins:
Pin corrosion: use the brass brush to make these pins shine again!
Here’s the brushed/cleaned pin:
Unfortunately, that corrosion can be inside the connector. Technically, these black housings can be lifted off by prying upward with a flush cutter to expose the spade terminals underneath—I wouldn’t go there if you don’t need to.
Once again, be sure to air out everything before re-applying power. I’ve brought devices back to life like this, you can too! The FED Forum is a great place to look for other fixes.