Yesterday, I did something dumb, in a hurry. I wanted to check the AC voltage at the terminals of a hair-dryer, to determine the voltage being applied to the terminals of the AC fan behind it. However, in a hurry, I plugged in the positive lead, to the unprotected 10Amp AC socket on the DMM, instead of keeping it in the regular 5Amp protected, 750VAC socket. While I do think the DMM showed me right (or expected) values of AC voltage (between 12-15VAC for fan), and I kept it connected only for about 5-10seconds at max., it apparently drained the 9V battery in DMM, and all other measurements started showing "1" or "Err". There was no smoke or anything, but no correct readings, or even a valid continuity test. I thought that it must be just the exhausted battery, so I replaced it with a brand new one from a pack, and still got same results. Then I tried yet another new battery, and still same. I checked batteries with 2 LEDs, and they were glowing pretty bright, and very feeble on the first battery I'd replaced, indicating that the new batteries were probably fine. I left the DMM there, and went ahead and ordered a new replacement (yet to arrive). Now all this was about 24hours back.
However, just before dumping the DMM, about an hour back, I thought of doing the continuity test one final time. Voila, it worked, as did every other measurement I took. While I am happy to know that my trusted DMM isn't dead after all, I was surprised that this seemed like some safety-fuse which had blown, but auto-reset after some time. Is this really true / possible ? This is a very cheap ($5) small basic DMM, bought from SEA, shipped free kinds.