Hi,
I have been using my Velleman DVM9912 for some years now but recently noticed that my resistance measurements are wrong. These are the things I observed:
-All functions except resistance work (checked against my dad's fluke)
-Without anything connected I measure 4k8 ish
-There is a PTC near the righthand connector on the board and when I hold it to warm it up I see the resistance measurement go up a few hunderd ohms
I don't remember what I've done wrong, one thing that could have happend is that I turned off the meter while measuring current.
Do you guys have any suggestions as to where to look ?
(And what could be the function of that PTC ? Is it a protection device or does it some compensation for the temperature measurement ?)
Here are some more pictures:
http://imgur.com/a/YVxzI