RTK Facet v4.4 — OLED display not working after drop, but receiver still operates

GPS/GNSS
1

My SparkFun RTK Facet (ZED-F9P, firmware v4.4) recently fell approximately 4 feet onto dirt. It had previously been working normally.

Symptoms:

  • Initially, the unit would power on briefly, display “Shutting Down,” and turn off.

  • Eventually, the OLED display stopped working entirely.

  • Neither the external nor internal power button appeared to restore the display.

  • The charging LED illuminates normally.

Troubleshooting performed:

  • Charged the battery and disconnected/reconnected it to reset the power system.

  • Disassembled the unit and inspected internal connections; no obvious damage found.

  • Connected to Windows via USB. Three serial ports were detected, including CH340.

  • Connected using PuTTY and confirmed the ESP32 is running firmware v4.4 and producing diagnostic messages.

  • Battery reports 100% charge at 4.19 V.

  • Bluetooth LE is functioning; SW Maps successfully connects to the Facet.

  • Confirmed SW Maps can connect while the Facet operates on battery power alone, without USB.

  • GNSS satellite reception has not been tested because the antenna is currently disconnected.

Current condition: The receiver appears to be operating internally, including on battery power, but the OLED display remains completely blank. Power-button operation has not been conclusively verified.

Could this be a failed display assembly, ribbon connection, or power-button/control issue? Are there additional diagnostics I can perform, or is a replacement display assembly available?

2

Hey there, thanks for posting on the SparkFun forums. Sorry that your Facet has had a bit of a tumble there.

It could very well be that a ribbon cable had become dislodged.

I would recommend opening the unit up and taking a look. You can find instructions on how to do so here:

If you do not see anything obvious just try removing the OLED entirely and reseating to see if that helps.

Alternatively, you can purchase a replacement OLED assembly here:

Let us know how it goes. I hope you find success with your repair attempts in the meantime.

3

I have removed the display and was able to turn on the unit successfully with the internal button, but not consistently with the external button. One difference with my unit than what is shown in the Repair manual is the connection to the board from the display is different. As you can see, it doesn’t have the FPC type connector and so the cable seems to hard to get in place and stay there. When it is connected, it seems more problematic. Can you explain how I can get a better connection with the board from this cable coming from the OLED?

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4

It seems like contacts within the button are not making continuity when pressed resulting in no signal being sent to the controller.

Also, it sounds like the connector for the display cable might be loose.

I think replacing the display/button assembly is probably your best bet for getting that facet working like it used to again.

I will PM you and we can go from there and see how best to proceed here.

5

Ouch, four feet onto concrete is rough. Glad the receiver itself still works though. I had a similar thing once where a screen died after a knock and it turned out the ribbon had just worked loose - worth a close look before buying the replacement assembly.