I am posting this in the hopes that it may spare someone else the confusion and anxiety I recently experienced when checking the mains AC voltage when building my Stereomour II.
Carefully following the manual instructions, I took a reading of my mains VAC and got ... 146VAC. Looking through the manual I saw that there was no build option for 146 VAC - you either had to be below 130 or above 210. Confused, I set about testing the VAC out of various power outlets in my home: all 146 VAC. Then I began to freak out: that extra voltage might be frying my electronics! And was about to unplug everything and call the power company, when it occurred to me try changing the batteries in my multimeter. Put in a new rechargeable battery and problem solved: 122VAC.
Prior to this, I would have assumed that if the battery was running low, the meter would stop functioning. Apparently not.
I wonder what other weird readings a low battery might cause.
So check your batteries!
cheers,
Derek