Fluke 179 problem measuring resistance

[neskor]

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!

[neskor]

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

[neskor]

some pictures of the PCB

[m k]

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.

[neskor]

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. 

[neskor]

Diode test also is not good, getting -1.834V for a 1n4003

[m k]

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.

[neskor]

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 VDC

Then I tried to measure the resistance on each setting, results were:
V AC - 0L
V DC - 11.10M
mV DC - 4.229M
R - 1.984M
Buzzer/Diode - 3.435M
mA - 10.99M
A AC/DC - 10M

[m k]

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.

[Harry_22]

 Hi!

I have the same Fluke 179.
If you need any measurements please let me know.

[neskor]

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.

[floobydust]

What part number is on the protective clamps? Some old Fluke used diodes, others use select low leakage transistors. I would test them.

[neskor]

Check here:

[neskor]

tested, they are all good

[neskor]

I can see there is a slight discoloration on the top of Fluke 642998 ASIC, maybe went south???

[Harry_22]

Hi!
I have following differences:

Ω - 2,64VDC
))) - 7,32VDC
Diode - 7,32VDC

mA - 2Ω
A - 0,3Ω

[neskor]

Thanks!
I double-checked my working 87V and I'm getting similar results:
Ω - 2,76 VDC
))) - 7,345 VDC
Diode - 7,336 VDC

[m k]

Top left corner of the chip is not promising.

[CharlieD]

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.