Hola All
Maybe some of you have the same fault, then listen - maybe we can find a solution.
I was delighted with its possibilities, until after about a year of use it started to turn off shortly after starting the measurements - dark screen. The working time on subsequent launches was getting shorter and shorter. It happened even after freshly charging and disconnecting the charger, and finally the battery did not hold voltage and could not be charged either from an external charger or via USB from a laptop. .
I installed a new battery for the VNA, fully charged it (green LED) and started convinced of the success. And here's a disappointment - the battery can only last a quarter of an hour of work, charging via USB from a laptop does not keep up. The removed battery, after being charged and reinstalled, discharges even without turning the instrument on. Something went wrong with the VNA system!
After opening the housing, it turns out that the 1R5 ohm resistor gets very hot (you can burn yourself) and the FM9688AA chip that manages the power supply.
I do not see any electrolytic capacitors on the board that could cause a short circuit.
I will try to save this graceful device by replacing the suspect IC.
Do you have any more ideas?