I have had a similar experience,with the very tiny voltageregulator of the usb powersupply................on the ensemble TXRX
When testing after completion of stage 2 as specified by the excellent building notes by WB5RVZ
I suspect to have a malfunctioning LP2992AIM5-3.3V regulator.
I carefully soldered all the componennts required for this stage including the regulator into its place on the PCB
I think I took all the required ESD precautions with respect to static electricity.
So everything is on same groundlevel i.e. the Weller soldering station, the printholder and my wristband.
After completion I tested the voltages of the usb powersupply ............... but nothing on my digital multimeter.
The 12V and 5 V of the main powersupply are OK.
And there is no (ground) connection between the mainpowersupply and the USB powersupply.
So in my opinion the main suspect is likely to be the LP2992AIM5-3.3V regulator.
Any other simulair problems ? and please suggestions how to solve this?
I think the best thing to do would be installing a new LP2992 .................. but where to get this tiny part in Europe ????
(not available at my regular sources Conrad , Display or Reichelt)
I will not continue building the ensmble TXRX before this stage is functioning OK.
best 73 Rinus PA2MPD