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Products => Test Equipment => Topic started by: Tallie on February 25, 2016, 03:52:14 am

Title: Fluke 77 Series II resistance measurement is slow to settle on a value
Post by: Tallie on February 25, 2016, 03:52:14 am

What could cause my Fluke 77 to be slow to settle on an ohms measurement? It's currently connected to a 560 ohm resistor, the reading started at ~630 ohms and has taken about fifteen minutes to creep down, ohm by ohm, to a reading of 575 ohms. I think it has settled on 575 ohms now but it's difficult to tell because when connected, it creeps quickly at first, and then slower and slower. One ohm at a time. It just turned to 574 ohms...

Title: Re: Fluke 77 Series II resistance measurement is slow to settle on a value
Post by: retiredcaps on February 25, 2016, 04:02:26 am

A number of things.

1) dirty/contaminated pcb, leads, input jacks, test probes.

2) bad input protection components (PTC, MOVs, fusible resistor, spark gap).

3) weak, low battery.  The Fluke 70 runs an amazing 2000 (two thousand) hours on a 9V battery, but a low or weak battery can cause funny readings.

Try a fresh battery first.  If that doesn't work, then I suggest a thorough IPA cleaning of all the components listed in #1 and then retest.  Let the pcb dry completely by running a fan or letting it dry for 24 hours.

For #2, the components are listed in the Fluke user/service manual and you can test all the components in circuit and compare them to the values listed in the manual.