Fluke Woes

[Helmholtz]

Since a while I have a Fluke 87V meter (bought new, was around 600€). Actually haven't used it a lot yet.
It came with a nice set of TL175 TwistGuard test leads. These leads alone cost around 60€ when bought separately.
The Twist Guard thing means that the exposed length of the tip can be varied by twisting the probe shell.
A few days ago I wanted to measure some speaker DCR and got nonsense readings.
Way too high and not repeatable.
With shorted tips the meter reading was above 20R and changing.
I measured the resistance of each lead using my PeakTech LCR meter with Kelvin clamps and got somewhat different readings for the leads but both around 10R.
Typically I expect a good test lead to have a resistance of 0.1R max.
A then found out that operating the twisting mechanism a few times tended to lower resistance by a few Ohms.
So I figured that there must be some sliding contact in the probe. Maybe dirty or corroded
I worked some D5 into the probes from the tips and after a couple of hours and more twisting the resistance per lead finally dropped to 0.1R showing that the leads themselves are good.
So a meter reading of 0.2R with shorted tips now.
Acceptable - but reliable?? Not sure.
Very disappointed of Fluke and the quality of the new and barely used test leads.

https://www.fluke.com/en-us/product/...ds/fluke-tl175

[tedmich]

I feel your pain! Good leads are difficult to find. I used to buy Pomona leads to backup my Flukes but then Fluke bought them.

Some like their Probe Master leads, I'm going to get their 8017S set ($25 USD) next time my Flukes read oddly.

[nevetslab]

I assume the Fluke 87V has a REL mode to offset the lead resistance. I have that feature on my Fluke 8060A DMM’s. For daily dirt work I’ve been using Probe Master with good results. Have Keithly Kelvin Leads for the precision work.

[Helmholtz]

I assume the Fluke 87V has a REL mode to offset the lead resistance.

Yes, of course I tried that first.
But as the leads' resistance wasn't constant, it wasn't a big help.
I do have other meters as well, but I expect very low and stable leads' resistance from a meter like this.
Imagine I would try to measure a 1A current with 20R leads' resistance.
That would melt the probes with 20W dissipation.
Big safety risk when measuring the input current of a PT.

[Chuck H]

I would have expected better from Fluke for certain. Reliable slip contacts aren't a mystery. But more than that I wouldn't have used a slip contact for the design. I would have made it so the tip travel was purely mechanical. If you've had trouble you can bet others have too. Fluke has probably corrected the problem and I'd bet the new probes are more reliable.

[Jon Snell]

Fluke offer a lifetime warranty.
Return to Fluke for a free replacement/repair.

[drewl]

I'm hard on my test gear and have repaired Pamona leads several times. Just this morning at work actually.
The wire at the mini grabber breaks internally all the time.
I heat some bus wire with soldering iron and push it into the mini grabber until it makes contact with the metal inside, solder the wire to that and put heat shrink over it.

[g1]

Fluke offer a lifetime warranty.

Maybe that is just for certain things. When I look up those test leads, it says 1 year warranty.

edit: even the lifetime warranty is a little nebulous. They define it as minimum 15 yrs. from purchase, and limited to 7 yrs. after product discontinued.

[Tom Phillips]

...then found out that operating the twisting mechanism a few times tended to lower resistance by a few Ohms. So I figured that there must be some sliding contact in the probe. Maybe dirty or corroded...

I agree that the problem is surprising and unacceptable. I have a set of the same probes only mine are branded Pomona 7519A Twist Guard Test Probes. Same product since Fluke continued using the Pomona name after they bought the company in 1999. My take is that the moving shroud is purely mechanical and independent of any electrical contacts. There is also no reason for a sliding electrical contact because the metal probe tip is fixed in place and the plastic sleeve just moves over the metal probe tip. I speculate that there is a problem with a crimp contact to the lead wire and the D5 soaked in far enough to reach that contact point. The internal lead wire specification is 18 AWG, 192 x 41 bare copper.

[Helmholtz]

My take is that the moving shroud is purely mechanical and independent of any electrical contacts. There is also no reason for a sliding electrical contact because the metal probe tip is fixed in place and the plastic sleeve just moves over the metal probe tip. I speculate that there is a problem with a crimp contact to the lead wire and the D5 soaked in far enough to reach that contact point.

Makes a lot of sense, thanks.
Will contact my dealer as well as Fluke Europe.

[Tom Phillips]

Makes a lot of sense, thanks. Will contact my dealer as well Fluke Europe.

Let us know how that works out. After Jon Snell wrote about a Fluke Lifetime warranty in post #6, I checked my Fluke owner's manuals and only found mention of a 1 year warranty. That may cover you for the current issue.

[stokes]

Dont know if its relevant but I have an older Fluke 73 and a newer Fluke, dont recall the model # but both will from time to time show erroneous resistance readings when shorting the tips of the leads, standard Fluke leads, and its a sign the battery is getting low. Change the battery and they function just fine.

[Tom Phillips]

Dont know if its relevant but I have an older Fluke 73 and a newer Fluke, dont recall the model # but both will from time to time show erroneous resistance readings when shorting the tips of the leads, standard Fluke leads, and its a sign the battery is getting low. Change the battery and they function just fine.

Good point! It's probably not the issue for the current test lead problem but is important to keep in mind when someone is getting unstable & unexplainable readings when doing general troubleshooting.

I have a Fluke 79. Bought new in 1992. The battery lasts a very long time but when it gets low, all the readings are suspect.

[Helmholtz]

Sure, but doesn't apply here.
Meter works fine with other test leads.
Also any decent DMM has a Lo Bat indicator.