At nanoVNA – measurement of two 920MHz LoRa antennas I mentioned my growing frustration with the USB interface on the nanovna, particularly the tendency to reset the nanoVNA with the slightest wiggle and the frustration in trying to use the resulting mess.
I have previously cleaned both plug and socket a couple of times, the last time was after some board modifications and flux residue was washed from the board keeping the USB socket dry, then the USB socket was flushed with clean solvent and blow dry.
The USB problems have become apparent only recently and rapidly got worse.
Close inspection showed the socket soldering on the PCB to be fine, and no broken or loose parts.
I observed the 5V rail whilst wiggling the connector, and there was clear evidence of intermittent connection (above).
So, before binning it, I again flushed both plug and socket with aerosol isopropyl alcohol and blew them out with compressed air.
To my delight, the thing is now good (again), and no glitches, no resets.
The problem might be related to premature wear of insulating or metal parts in one or both connectors (ie Chinese Quality… bit of an oxymoron really).
So, it seems that the connectors get dirty easily (this has had lots of use, but in a clean environment), and at next sign of symptoms, the first measure will be to jet the connector parts with isopropyl alcohol.