Author Topic: Would you say this Fluke 17B+ is out of spec ?  (Read 2159 times)

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Offline AlxDroidDev

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Would you say this Fluke 17B+ is out of spec ?
« on: January 05, 2017, 02:01:53 pm »
In another thread, I stated that my Fluke 17B+ was way of calibration spec., specially when compared to the results of a Fluke 117. When I contacted Fluke's support, I said that I was trying to read the output of a voltage reference, be it a MAX6126AASA41+ or a MAX6126AASA50+, or even a ISL21009DFB841Z (4.096 Vref from Intersil, which is what is all I have left on hands right now: the MAX6126 are gone). They told me that the difference in reading was expected, because the Fluke 17B+ would only properly read resistive voltages, and a voltage reference was a capacitive voltage. I had no was to refute that argument because I didn't know if the guy was right or wrong.

Anyhow, I ran more tests on a voltage divider using two 10k Ohm 2% resistors, measured to be within expected accuracy. According to the Fluke tech support guy, this should be enough.

I also ran tests using a variable PSU based on a LM317 and the same voltage divider.

According to http://www.fluke.com/fluke/brpt/multimetros-digitais/general-purpose-multimeters/fluke-17b+.htm?pid=78682, the specs for DC for the 17B+ are:


FunctionRangeResolutionPrecision
DC Voltage4,000 V
40,00 V
400,0 V
1000 V
0,001 V
0,01 V
0,1 V
1 V
0,5% + 3

In my tests, I also compared it to a cheap Mastech MS8260E (bought from DealExtreme several years ago). The funny thing is that in all the tests, the Mastech's results were always on pair with the Fluke 117.

Here are the results I got:

Output from a ISL21009DFB841Z:

MethodFluke 17B+Fluke 117Mastech 8260E
Direct reading4.0504.0974.09
10k/10k voltage divider2.0202.0442.03


In the second part of the test, I used a variable PSU based on a LM317, and used the Mastech 8260E to read its direct output. The LM317's output was also connected to the same voltage divider as above, and half of the divider was read by both the Fluke 17B+ and the 117. My expectation was to have the Flukes always give 50% of the reading of the Mastech. This is what I got:

Mastech MS8260EFluke 117Fluke 17B+
1.7640.8770.866
4.001.9991.975
5.002.4982.469
6.002.9992.963
7.003.4953.454
8.003.9923.945
9.004.4934.44
10.014.9954.93
10.635.3015.24

Conclusion: the Fluke 117 and the MS8260E are giving compatible results, but I am not sure if I should pursue an RMA for the 17B+, and this is what I need your help with: is it really out of spec and, if so, is the table above enought argument to convince fluke that it is out of spec?

thanks in advance.
"The nice thing about standards is that you have so many to choose from." (Andrew S. Tanenbaum)
 

Offline Fungus

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #1 on: January 05, 2017, 02:12:37 pm »
They told me that the difference in reading was expected, because the Fluke 17B+ would only properly read resistive voltages, and a voltage reference was a capacitive voltage. I had no was to refute that argument because I didn't know if the guy was right or wrong.

Sounds like BS to me. A voltage is a voltage. There's no such thing as "resistive voltage" and "capacitive voltage".

(there's resistive loads and capacitive loads but I've never heard those terms applied to voltage)

I am not sure if I should pursue an RMA for the 17B+, and this is what I need your help with: is it really out of spec and, if so, is the table above enought argument to convince fluke that it is out of spec?

If you've got a variable voltage LM317 PSU then dial it to 3V (as measured on the 117) and do a calibration on the 17B+. See what happens.  :popcorn:

(I think it was a 3V reference to calibrate a 17B+, correct me if I'm wrong)

« Last Edit: January 05, 2017, 03:10:00 pm by Fungus »
 

Offline tautech

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #2 on: January 05, 2017, 03:04:29 pm »
A few seconds searching within the forum found this thread:
https://www.eevblog.com/forum/testgear/calibration-of-fluke-1517-b-('plus')/

READ REPLY #7

Get yourself a DMM Check and you'll have them all spot on.
« Last Edit: January 05, 2017, 03:28:56 pm by tautech »
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Offline AlxDroidDev

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #3 on: January 05, 2017, 04:14:02 pm »
The thing is that if I remove the calibration sticker, Fluke won't give me an RMA under warranty.

So that is exactly the point: is it out of spec enough to bother sending it to Fluke? I know I could simply calibrate it myself, but that will void any chances of having Fluke itself do it for me.
"The nice thing about standards is that you have so many to choose from." (Andrew S. Tanenbaum)
 

Offline Fungus

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #4 on: January 05, 2017, 06:20:08 pm »
The thing is that if I remove the calibration sticker, Fluke won't give me an RMA under warranty.

What sticker? You have to take it apart to change the fuses and when you take back off you get access to the calibration pads.

It's fiddly to power the meter with the back off and no battery holder but there's no need to break any stickers.

See this video at 15:00



Edit: Calibration manual here: http://assets.fluke.com/manuals/15BPlus_cmeng0000.pdf
« Last Edit: January 05, 2017, 06:24:39 pm by Fungus »
 

Online wraper

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #5 on: January 05, 2017, 06:28:19 pm »
Seems that voltage reference is off as all of the readings are lower by about the same ratio. As adjustments on this meter are made by a lot of pots, I wouldn't be surprised if one of them moved a little bit during shipping.
 

Offline Fungus

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Re: Would you say this Fluke 17B+ is out of spec ?
« Reply #6 on: January 05, 2017, 11:17:27 pm »
As adjustments on this meter are made by a lot of pots.

That was the original 17B. The newer 17B+ is electronic, I think there's only one pot in it. Calibration is electronic.
 


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