Fluke 179 problem measuring resistance  - Page 1
Forum section: electronics / repair

author: neskor
author_rank: Contributor
timestamp: June 02, 2024, 11:16:27 am
content: Hi.I recently received Fluke 179 in great condition, but in Auto mode doesn't want to measure resistance.Strange, it measure correctly if I first power off the meter and then connect probes to resistance and then power on the meter, in that case it measure OK, but once I disconnect the probes from resistance and try again (while the meter is still powered) to measure it doesn't measure.Also workls OK if I switch from capacitance or other measurment back to resistance.Anyone has a clue what is the problem.Thanks in advance!

author: neskor
author_rank: Contributor
timestamp: June 02, 2024, 12:30:29 pm
content: Tried this troubleshooting from the other posts:1) The three MOVs all measure infinite resistance using another Fluke 87V multimeter.2) The green fusible resistor just below the three MOVs measure roughly 1k ohm.3) The black PTC just above the volt/ohm jack measure around 1.1k ohm.4)With fluke 87V in mVDC mode I'm getting 4.2M, it should be 10M ohm?5) It VDC mode. With another Fluke meter I measured around 11.11M ohm.6) Tried to measure a 1.5 AA cell, and 179 shows 1.6 VDC, confirmed the same value with working Fluke 87V

author: neskor
author_rank: Contributor
timestamp: June 02, 2024, 12:32:53 pm
content: some pictures of the PCB

author: m k
author_rank: Super Contributor
timestamp: June 02, 2024, 04:07:37 pm
content: Seems that something is loading but not unloading correctly.Capacitance mode should also has an active internal voltage,same with frequency.Maybe one switch has a problem.

author: neskor
author_rank: Contributor
timestamp: June 02, 2024, 05:42:52 pm
content: Tried to measure capacitance, DC and mVDC and results are good.Temperature measurments are less valid, around 5C error.And doesn't want to measure frequency of AC signal.

author: neskor
author_rank: Contributor
timestamp: June 02, 2024, 08:40:04 pm
content: Diode test also is not good, getting -1.834V for a 1n4003

author: m k
author_rank: Super Contributor
timestamp: June 03, 2024, 11:53:15 am
content: Is there a same constant voltage between probes before and after Ohms measurement?AC freq and diode test indicates that there are too much initial voltage present.But since VDC is good that presence is not permanent.

author: neskor
author_rank: Contributor
timestamp: June 03, 2024, 12:09:21 pm
content: If I plug my other working MM directly into 179 inputs I'm getting 1.2VDC and quickly drop to 0.642VDC on resistance and 2.636VDC on the diode position.On all other settings, I'm getting zero VDCThen I tried to measure the resistance on each setting, results were:V AC - 0LV DC - 11.10MmV DC - 4.229MR - 1.984MBuzzer/Diode - 3.435MmA - 10.99MA AC/DC - 10M

author: m k
author_rank: Super Contributor
timestamp: June 03, 2024, 06:35:58 pm
content: Your other meter can be overloading.Measure voltage again but put this time a real resistor in between, kilo range is fine.Then you can also check how that voltage does when you try measuring that resistor again.Manual says that mVDC should also be 10M.Near 5M is suggesting that other 10M is involved.You can also try disconnecting those high voltage safety components.Maybe one can't stand it anymore, after who knows how high peak.

author: Harry_22
author_rank: Frequent Contributor
timestamp: June 03, 2024, 06:48:22 pm
content: Hi!I have the same Fluke 179.If you need any measurements please let me know.

author: neskor
author_rank: Contributor
timestamp: June 03, 2024, 07:58:59 pm
content: Tried to measure voltage again this time with a real resistor in between, 2K4.Voltages are 0.194V on resistance and 1.283V on the diode, but when I disconnect only the probe from 179 and connect again, I get no voltages, but if I turn off the 179 or move the switch back to the resistance I get again voltages.

author: floobydust
author_rank: Super Contributor
timestamp: June 03, 2024, 09:27:26 pm
content: What part number is on the protective clamps? Some old Fluke used diodes, others use select low leakage transistors. I would test them.

author: neskor
author_rank: Contributor
timestamp: June 04, 2024, 04:46:55 am
content: Check here:

author: neskor
author_rank: Contributor
timestamp: June 04, 2024, 05:12:45 am
content: tested, they are all good

author: neskor
author_rank: Contributor
timestamp: June 04, 2024, 05:23:57 am
content: I can see there is a slight discoloration on the top of Fluke 642998 ASIC, maybe went south???

author: Harry_22
author_rank: Frequent Contributor
timestamp: June 04, 2024, 10:58:00 am
content: Hi!I have following differences:Ω - 2,64VDC))) - 7,32VDCDiode - 7,32VDCmA - 2ΩA - 0,3Ω

author: neskor
author_rank: Contributor
timestamp: June 04, 2024, 12:20:49 pm
content: Thanks!I double-checked my working 87V and I'm getting similar results:Ω - 2,76 VDC))) - 7,345 VDCDiode - 7,336 VDC

author: m k
author_rank: Super Contributor
timestamp: June 04, 2024, 12:32:51 pm
content: Top left corner of the chip is not promising.

author: CharlieD
author_rank: Contributor
timestamp: June 04, 2024, 04:12:20 pm
content: I had a smilar issue with a Fluke 179, and a clean of the rotary selector with IPA solved the problem, some particle of dust or something else could be the problem. Also, in other models when I have something bad with specific measurement function, sometimes broken tracks/vias because of battery corrotion was the problem, check for these.