Jeff Liebermann wrote:
On Mon, 3 Sep 2012 20:08:54 +0000 (UTC), Cydrome Leader
wrote:
Got a spiffy 87 series V meter from Specialized.
Oh-oh. If you have one of the older units, you may have RF
susceptibility problems, which includes clearing the flash and
bricking the meter (15min):
http://www.eevblog.com/2010/09/18/eevblog-112-gsm-vs-the-fluke-87v-multimeter/
and the fixed version (18min):
http://www.eevblog.com/2011/07/11/eevblog-185-fluke-87v-multimeter-gsm-fix/
Old and new versions comparison:
http://www.flickr.com/photos/eevblog/sets/72157627120630430/
or just listen to the beep. The old model has a rather loud beep. The
new version has a much quieter beep. Also, the new one comes with
shrouded probe tips.
It's really hard to tell what the heck those photos are supposed to be,
but I do have the one with the metal stub on the mode selection switch,
which would be rev 11 or the new one, I think.
So I just ran a test.
power on meter with no leads. Great.
I then dampened a qtip and squeezed it as dry as it can get as they're too
fat to slide in the jack all the way when fluffed up.
I jammed it into the uA range jack and the meter started the several beeps
er second and LEAd (or whatever it looks like in 7-segment) freak out
input protection mode.
I stuck the other dry end of the qtip in the jack and it still won't
settle down, even after being shut off and on. A second qtip still can't
dry the jack enough. No amount of rotating or just straight up and down
action with any number of qtips seems to dry the thing out enough to work
again.
The only ranges that act normal are mA and uA.
From this photo
http://www.flickr.com/photos/eevblog...7627120630430/
You can see there are two solder leads per jack. It seems that one side is
the "working" terminal of the jack and the other is just for sensing when
a probe is inserted because it will short out both pins. Inside the red
plastic jack each half terminal is just a nearly semicircle shaped contact
that wraps around almost half the banana-ish plug you's stick in there.
Whatever they're sensing must be in the microvolts or microamps of leakage
between those half terminals. Whatever it is, it's way over sensitive.