Uni-T UT139C - freezes after turning on

[Aborus]

Hi

I need help with my UT139C. After 1,5 years it suddenly stopped work. Normally it beeps two times after turning on and then it's ready to use. But now it freezes after first beep. The buttons are kind of working, i can turn on backlight, and the symbols on lcd changes.
When i turn on meter in calibration mode and then go to normal mode it can measure but only in DC.

To clear things up i made a video illustrating problem: https://youtu.be/FATLlHZkn5E

Do you have any idea if this can be repaired? Maybe reprogramming eeprom? Or do i stuck with paperweight?

Any help would be appreciated

[stj]

try cleaning all the switch contacts.

[daedalux]

Try disassembling it completely to the bare lcd, switch contacts, all clean, check fuses, broken solder joints and put new batteries on it.
I have had this model for four years without issues.
It's important if it failed after being dropped to the ground, overvoltage, overcurrent, or even high electromagnetic field as it has no contact voltage detection.

[Aborus]

I cleaned all the contacts, fuses are ok, solder joints look fine too, i couldn't find any broken or bad joints. I tried changing batteries.

It hasn't been dropped, overcurrented or sustained any damage. I used it only in low voltage applications. It was working fine, then sit for a month in desk, then i took it out and tried to turn it on and it wasn't working.

[lordvader88]

Do u have another meter or oscilloscope to start poking around ?

I have a FS9922-DMM4 based VC99, and it freezes and does weird things because the selector knob/contacts are doing something wrong and making extra contacts or not enough sometimes. I doubt I've done anything to damage it's chip, only working at breadboard stuff with 1-2A @12V if it all went bad.