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QDX Rev 3 worked fine 2 days ago.

Today connected it to a dummy load and applied 12V with nothing else connected and
LED1 blinked fast continuously.

Plugged USB into laptop but QDX file system did not appear nor as any USB audio or serial device.

Removed power, rechecked connections and reapplied power and now LED1 is dark and USB does not appear either as file system, sound device or serial device.

11.59V in @ 110MA. Measured 5.01V and 3.31V at the regulators, and the 25MHz clock is present.

I would assume the OS is corrupted, so how does one bootstrap the CPU?


73 Kevin
K3TL

Found the solution to this problem here:

/g/QRPLabs/message/116094

Evidently the firmware file was corrupted preventing the QDX from initializing and making it appear unresponsive

The post linked above referenced a point on the board where I2C_SDA could be held low while powering up, but is applicable for a Rev 2 board. Mine is a Rev 3 and the test points near those referenced are not the same.

I had to go to the EEPROM and hold pin 5 low while powering up. Once the front LED starts rapidly flashing then remove the low off pin 5.

This caused the EEPROM from being read and the DFU put the QDX into the state where one can copy the fresh firmware file via the USB to the? QDX file system and the rewritten to the EEPROM.

All is back to normal now.

73,
Kevin K3TL