An Update On AN8008 Multimeter

I wrote about the AN8008 multimeter.  I have been generally happy with the meter.  But more recently, I started to notice some problems: the meter sometimes does not start up correctly, I have to turn the rotary switch a few times; and more annoyingly is that the resistance measurements seem off: the shorted resistance can be 5 to 10 Ohms or more.  Initially, the meter also displays low-battery sign;  I measured the batteries; it seems that they should be OK.  But I changed batteries anyway, but the things did not improve.   I suspected that the rotary switch contacts might be the issue.  I opened it up and found solder flux residue on the PCB circular tracks that make contact with spring clip on the rotary switch.  I cleaned the board with alcohol; the flux was easy to clean.   After that the problem seems to go away; the probe short resistance is about 0.2 Ohm.  

It is interesting the flux residue that has migrated overtime since it was not a problem initially.