USB jacks / ports

The USB jacks at the rear of the unit are fully waterproof!
However they must be protected from debris, and sea water (salt water) at any time by simply sticking a strip of sticky-tape over them.
Debris and dirt will obviously prevent the USB plug inserting all the way, thereby causing connection problems.
Salt water is not really a problem for a short time only (30 to 60 minutes) but having salt water in the jacks for prolonged time (even water residue) will cause the delicate contacts to oxidize, and in the long term result in bad or failed connection. Therefore, after salt water entered the ports, it is vital to blow out the ports with air carefully, and best add a tiny spray of WD40 to displace all the moisture.

FUNCTIONS:
The top USB port (master) is ONLY for plugging in a flash drive!
Once plugged in, and correctly formated, the LS3 will upload ALL available logs to the flash drive.
See more details here: How to download LOG files and Requirements and specs for USB flash drives
Note that it has no effect when a charging cable is connected to this port.

The bottom USB port (slave) is for charging, firmware updating, and high speed USB connection to PC.