Multimeter Repair

My relatively new BK Precision multimeter got rained on, a leak in the roof on the deck soaked the table I was working on when some heavy overnight rain decided to come bucketing down. To say it was rained on is an understatement really, it must have been placed perfectly under a torrent of water that jammed more water into the meter than there was air.

Needless to say, I was rather pissed off. I pulled the battery cover off, and a large quantity of nasty looking brown water came pouring out. I proceeded to dismantle the meter, cleaning and drying all traces of water. I put it back together with a fresh battery, flicked the range switch around, and nothing…

Shit… So I pulled it apart again to have a better look at the board. It looked fine first time around, but under closer inspection I noticed that several of the tracks leading away from the positive battery snap solder joint were corroded away down to bare fibreglass board. I followed the trace until I found an undamaged section, scrubbed the green mask off the trace and installed a small piece of wire in the damaged sections place (small 30 gauge wire, what was used to fix mistakes on prototypes and the like ages back).

I plugged the battery back in and to my relief the multimeter was working!!

The meter still seems to perform as well as it did before, hopefully it stays that way. I can only assume that the tracks were damaged due to some sort of electrolysis effect. The meter was left in the on position and it had gone into auto-off mode but still using some power, a likely culprit. The corroded tracks started from the exposed copper vias through the board, eating into the copper underneath the green lacquer on the board. Bit of a shock that it happened so quickly!!

On a side note, while cleaning the meter I found a track underneath the screen that had been cut during manufacturing. What looks like a date code possibly points out that it was built in 2008. Is mine an early model? Interesting…