Problems with a Fluke DMM 79 III True RMS: blinking Display in resistance pos.

[Matse.P]

Hey guys,
I god a brand new problem using my Fluke 79 III TRMS DMM measuring the resistance!

When I switched it to low ohms resistance range, everything was ok.

But today at 4 pm,, I switched it to high resistance range and as I tested it by shorting out the terminals with the red measuring line I got the following result:
The screen blinks and the measurement value is at least negative

What's going wrong here? I've never seen such a behaviour before, nut at a Fluke nor any other DMM I own.

Please have a look:
https://www.youtube.com/watch?v=rcMxsW_HsRE&feature=youtu.be

What happend? After some hours, the Fluke healed itself and still works fine until now.

Is it out of cal so that the measurement of high resistance maybe went down unter 0 Volts in the measurement circuit or what's the deal?

I couldn't find any dependencies on moisture or temperature or something like that.

Any ideas?

Thanx a lot from germany,
Matthias

[retiredcaps]

1) Look at your video.  The low battery indicator is clearly shown.  Try putting in a new 9V battery and retest.

2) If you had an oops moment, you may have damaged your fusible resistor (symptom #3)

http://mrmodemhead.com/blog/fluke-87-fusible-resistor/

3) If neither of the above, take apart your meter and post clear focused pictures of both sides of the pcb.

[Matse.P]

D'Oh! 

Used down battery -> I believe a change would solve the problem  !

I thought the indicator should go from full to empty to show a low battery stage but for this fault a low battery makes sense so that the DMM is no more able to measure the resistance in a right way ...

Sorry for my little daffy question ...

Thanx a lot for your answer!

Greetz,
Matthias

[retiredcaps]

I thought the indicator should go from full to empty to show a low battery stage but for this fault a low battery makes sense so that the DMM is no more able to measure the resistance in a right way ...

On some multimeters, there is a status battery indicator that shows you the approximate battery level.  But for the 79 III, it definitely indicates low battery as per snippet from manual.

http://assets.fluke.com/manuals/7926____iseng0200.pdf

[retiredcaps]

Here is a picture of the Agilent U1272A.  You can see it has a battery level indicator which is showing "full".  When it reaches near empty, it will only show one bar and if I remember correctly, when it blinks the batteries need changing now.

[retiredcaps]

One last comment on this subject.  Fluke makes a lot of meters that vary with respect to battery life. 

For example, I put "dead" 9V batteries into a Fluke 75 II and I can probably squeeze out another 200 to 300 hours of use since it only consumes < 300uA (microamps).  The Fluke 75 II battery life is 2000 (two thousand) hours using a single 9V battery.

One of my favourite meters is the Fluke 187, but the 4 AA cells only last 72 hours.  I use rechargeable nimh eneloops so it is not a real problem, but others might find it annoying.

The new Agilent U1280A uses 4 AA cells and is rated at 800 hour battery life. The Fluke 28 II uses 3 AA cells and is rated at the same 800 hours.

[Matse.P]

Thanx a lot for your information! No I see clearly what's going on ...