Fluke 179 AutoRange -> changing unit prefix after removing leads

[Ulli211]

Hi,

i found out that my Fluke 179 changes the unit prefix in the AutoHold-mode after removing the test leads.
For example: measure AC voltage in auto range and auto hold -> holding test leads to connector -> piep -> correct value and unit with prefix written in display (230V) -> removing leads -> correct value in display but changed unitprefix (230mV).
same with resistance: 0,8 Ohm -> 0,8 MOhm

That occurs in AC-voltage and resistance measure mode only. DC-Voltage measurement works fine.

is the dmm defect or is that only a strange behavior? i bought it used on ebay.

regard from germany,
Ulli

[ModemHead]

I have two 179s here of different vintage, and neither of them exhibit the behavior you describe.  The only thing that changes in Autohold mode when I disconnect the leads is the bar graph and it's associated scale and units, which is OK because the bar graph is always "live".

[retiredcaps]

is the dmm defect or is that only a strange behavior? i bought it used on ebay.

If you bought an early release model (say 1999 to 2003), check to see if it being recalled by Fluke. Recalled units have a serial number below 79000000.

http://www.cpsc.gov/en/Recalls/2002/CPSC-Fluke-Corp-Announce-Recall-of-Digital-Multimeters/

Though you are not the original owner and do not qualify, Fluke may want to get the meter and repair/replace it regardless due to safety/liability.

If your unit is not recalled, then open it up and post clear focused pictures of both sides of the pcb.  Dirt/contamination can cause all sorts of funny things.

[Ulli211]

I made a video:
https://youtu.be/OGCSK3kn-XQ

Maybe it depends on the firmware-version? my device has 2.02.5 (press HOLD-button while switching it on).
i think its quiet old, has no serial-number on it and the calibration-button is at the bottom.
would you suggest to return it to the seller?

[ModemHead]

Definitely contamination can cause all kinds of weirdness, but usually on the analog side.  That behavior looks a lot like some sort of firmware bug.   

Both of my units report 1.02.5 even though the SNs are very different (783x and 810x.)  Maybe someone with a 2.02.5 unit could check as well.

[Ulli211]

thanks you both!

the problem is, that i'm not the original owner and the sticker with the serial-number is not on the device. what do you think? will fluke repair it anyway?

[retiredcaps]

prefix written in display (230V) -> removing leads -> correct value in display but changed unitprefix (230mV).
same with resistance: 0,8 Ohm -> 0,8 MOhm

My 175 is firmware 1.02.3 and these are my results for the same test with probes removed afterwards.

[retiredcaps]

For example: measure AC voltage in auto range and auto hold -> holding test leads to connector -> piep -> correct value and unit with prefix written in display (230V) -> removing leads -> correct value in display but changed unitprefix (230mV).

The above is very dangerous.  The manual recommends NOT using autohold in the following situation.

"Warning
To avoid electric shock, do not use the Display HOLD or
AutoHOLD mode to determine if a circuit is live.
Unstable or noisy readings will not be captured. "

[retiredcaps]

Maybe it depends on the firmware-version? my device has 2.02.5 (press HOLD-button while switching it on).
i think its quiet old, has no serial-number on it and the calibration-button is at the bottom.
would you suggest to return it to the seller?

I think 2.02.5 is fairly recent, but without a serial number and the potentially dangerous situation, I think you should return it to the seller or contact Fluke to see if this is a firmware bug.  Explain with photos, how this can be dangerous when the autohold shows 230mV instead of 230V.

[Ulli211]

yes - its dangerous...

https://youtu.be/rvac-rb_c3g

[retiredcaps]

I would contact Fluke and have them read/watch this thread and your video to see what they have to say.  They may repair or send you a new one at no cost despite not being the original owner of the meter?

I would also not close the ebay case/auction by leaving positive feedback until this is resolved either by a refund from the seller or a fix from Fluke.  The missing serial number is a suspicious red flag.

[Ulli211]

I would contact Fluke and have them read/watch this thread and your video to see what they have to say.  They may repair or send you a new one at no cost despite not being the original owner of the meter?

Already done it. We will see how Fluke will respond.

I would also not close the ebay case/auction by leaving positive feedback until this is resolved either by a refund from the seller or a fix from Fluke.  The missing serial number is a suspicious red flag.

Yes - strange. There was only a blank white label under the stand. Is the serial number written directly to the unit (engraved)?

[retiredcaps]

There was only a blank white label under the stand. Is the serial number written directly to the unit (engraved)?

Here is a screenshot capture of Martin's Fluke 170 review.



The serial number shown in Martin's video is 14850875, which technically is below 79000000, is NOT subject to recall. Why? Fluke for some stupid reason decided not to go to a 9 digit serial number system after they ran out of 8 digit numbers and stuck with 8 digits which causes mass confusion.  Perhaps their IT systems are still running COBOL with fixed fields? Who knows?

[retiredcaps]

Is the serial number written directly to the unit (engraved)?

The first generation Fluke handheld meters (Fluke 8000, 70, 80) all had the serial number engraved into the unit.  I don't know exactly when, but they switched to white sticker labels with bar codes.  Presumably the bar codes helped reduce human keyboard errors and speed up the input of serial numbers into a database?

AFAIK, all Fluke 170 series have white bar code stickers since day 1.

[ModemHead]

Yes - strange. There was only a blank white label under the stand. Is the serial number written directly to the unit (engraved)?

Normally those little stickers are quite resistant to damage.  But once, I was cleaning (with soap and water) a very dirty used Fluke 170 series meter, and I noticed that all the black ink had disappeared during the procedure, leaving only the blank white sticker.  Oops.

[retiredcaps]

But once, I was cleaning (with soap and water) a very dirty used Fluke 170 series meter, and I noticed that all the black ink had disappeared during the procedure, leaving only the blank white sticker.

I'm very careful around that area when cleaning.  Recalls can happen many years later and I want to know the serial number of each meter.

[fergch]

Just had a look at my Fluke 175, version 2.04.3, and on AutoHold AutoRange, it measures mains ac voltage here in the UK 245v, and when both the probes are removed the meter re-measures the change in voltage (to zero) and is recording in the mV range. Re-connect the probes and the AutoRange changes to the V range and reads 245v. If only one probe is connected to the ac mains, the unit identifier changes from mV to V, still reading near zero, add the other probe the meter reads 245v.

Surely this is what one would expect, AutoRange AutoHold senses the change in voltage at the probe and records the result.

If the meter is in Hold it keeps the measured voltage at the time of the Hold press, and keeps the unit identifier (V or mV); and does not change when the probes are removed (or start at zero, press hold, connect probes to the mains, meter still reads the hold value, mV, and does not change to the V or to 245).

Serial is 16600263.

Oh, and one other thing, the function switch has to be moves to the Vdc position when holding the Hold button to see the firmware version, and on to the mVdc position to see the model (in my case F175). The first position Vac lights every sector on the display.

[retiredcaps]

Just had a look at my Fluke 175, version 2.04.3, and on AutoHold AutoRange, it measures mains ac voltage here in the UK 245v, and when both the probes are removed the meter re-measures the change in voltage (to zero) and is recording in the mV range. Re-connect the probes and the AutoRange changes to the V range and reads 245v. If only one probe is connected to the ac mains, the unit identifier changes from mV to V, still reading near zero, add the other probe the meter reads 245v.

Surely this is what one would expect, AutoRange AutoHold senses the change in voltage at the probe and records the result.

In the OP's video, the value is 226.9VAC and then the "m" annunicator comes on in front of the 226.9 V.  The digits 226.9 don't change at all.

In your case, does your meter show 245.1VAC and then 245.1mV AC?

[LightlyDoped]

I've got a 179 with firmware version 1.02.5. S/N begins with 815. My meter doesn't have this behavior.

[fergch]

I should have made it clear; no, in my case the readings drop to near zero and mV: it does not show 245mVac

[retiredcaps]

I should have made it clear; no, in my case the readings drop to near zero and mV: it does not show 245mVac

One more question regarding the behaviour of yours.  Does it beep each time when it drops to near zero reading?

[rsjsouza]

My Fluke 179 release 2.04.5 does not do this. The only thing that changes to mV when the leads are open is the bargraph scale.

[AG6QR]

My Fluke 179 release 2.04.5 does not do this. The only thing that changes to mV when the leads are open is the bargraph scale.

I also have a Fluke 179 with firmware 2.04.5, first four digits of S/N are 9934 (on white sticker with bar code), and it behaves properly, exactly like rsjsouza describes.

I notice on the videos of the misbehaving unit that the bargraph display changes at the same time as the units change on the main numeric display.  Sounds to me like a firmware bug -- the processor shouldn't have updated the display of units until a new sample is taken in autohold mode.

[rsjsouza]

My Fluke 179 release 2.04.5 does not do this. The only thing that changes to mV when the leads are open is the bargraph scale.

I also have a Fluke 179 with firmware 2.04.5, first four digits of S/N are 9934 (on white sticker with bar code), and it behaves properly, exactly like rsjsouza describes.

I notice on the videos of the misbehaving unit that the bargraph display changes at the same time as the units change on the main numeric display.  Sounds to me like a firmware bug -- the processor shouldn't have updated the display of units until a new sample is taken in autohold mode.

Funny, I was wondering if it could be simply grime on the zebra strip that would short both LCD "segments"...

[Ulli211]

Fluke replied: I need i firmware update. they can update it beside a calibration which i have to pay (82,50 EUR).

i will send the unit back to the seller and buy i Gossen Metrawatt .

byebye Fluke!