FLUKE 179

[ALEX-CY]

Hi from hot Cyprus.
I have a fluke 179 for many years now and am very happy with it untill yesterday. As i was working with the fluke the battery gone. After i replace the battery the fluke stoped working. The display is on put the autorange go from low to hi, the buzzer is working alone random the ohms icon and it comes on and off all the time and i can't measurt anything. The 11a fuse was gone(maybe was faulty from before) so i replace it with no luck. any advice please?
sorry for my bad english.

[goaty]

- Check if new battery is good
- Check if contact of battery is clean and not dirty or corroded
- If Fuse was blown, maby you measure wrong and damage the meter ? Also possible.

[ALEX-CY]

battery and contacks ok
no wrong measure. i think the fuse was blown from before

[goaty]

Also maby try leave battery out for five minutes, maby hickup in processor ? Unlikely but not impossible...

[ALEX-CY]

allready done over the night. no luck

[goaty]

Maby try open and clean PCB around main selector swich with IPA.

[ALEX-CY]

any help?

[Ed.Kloonk]

I don't know if I'm any help. But I do own a 179 and treat it terribly 'out in the field'.

One thing I have noticed is that if the battery is a bit low and continuity testing is wonky, I feed it a dose of 240vAC on the AC volts range and after that, the meter seems to have righted itself.

I have no scientific method, or anything to back up my claim. Only my word that it has happened more than a couple of times and it's no coincidence. That's how I fix it's funkiness.

[feedback.loop]

I don't know if I'm any help. But I do own a 179 and treat it terribly 'out in the field'.

One thing I have noticed is that if the battery is a bit low and continuity testing is wonky, I feed it a dose of 240vAC on the AC volts range and after that, the meter seems to have righted itself.

I have no scientific method, or anything to back up my claim. Only my word that it has happened more than a couple of times and it's no coincidence. That's how I fix it's funkiness.

Seems like superstition.

[Ed.Kloonk]

I don't know if I'm any help. But I do own a 179 and treat it terribly 'out in the field'.

One thing I have noticed is that if the battery is a bit low and continuity testing is wonky, I feed it a dose of 240vAC on the AC volts range and after that, the meter seems to have righted itself.

I have no scientific method, or anything to back up my claim. Only my word that it has happened more than a couple of times and it's no coincidence. That's how I fix it's funkiness.

Seems like superstition.

I know right?

[retiredcaps]

There are many internal revisions of the PCB.  Which one do you have?  Clear focused pictures of the PCB helps us help you.

A video posted somewhere with what is wrong will also help if English isn't your first language.  That way, we can see what the meter is doing.

[wizard69]

Even though you indicated "good" batteries I would still try a new set and look real closely at the battery connections.   Yes I know you have already looked at this but it is the first thing I would look at.

Second you may have a dirty switch.   I'd seriously consider tearing the meter down to the point where you can mechanically clean the contacts.   Anything beyond that will likely require diagnostic work.

Now before doing anything consider sending the meter back to Fluke for servicing.   At least on this side of the pond they have excellent service and support.   I don't even consider other handhelds due to the excellent service I've gotten in the past.

[Electronic_Arts]

Hi,

I have a same problem with my Fluke 179. After replacing battery with new one multimeter shows Ohm in all positions.
I uploaded a video where i show problem of my multimeter. Please look if anyone know what is going on with my multimeter.


1. I connected the multimeter to the laboratory power supply for testing, but the problem remained.
2. I mechanically cleaned all switch contacts.
3. Two fuses is ok not damaged.
4. PCB don't have damage because I checked it under microscope.

If you have any ideas, tell me what should I check?

[mir]

Hi,
My Fluke 179 developed identical symptom shortly after the battery replacement. The schematic of 179 couldn’t find it, however 87V that is closest down to component level is available in the internet.  The 179’s main part of the firmware still working, ie: back light turns on/off. The mode switch, Diodes, TRs, Fuses (only for a current measurement), Ferrite beads are all checked OK, but the problem still persisted.
One suspicions part I found is a look like a ferrite bead located near the microcontroller.  The resistance of this is approximately 50kohm. That is too high for either as an inductor or ferrite bead, and too low for a capacitor. Replacing this part to ferrite bead or capacitor did not fix the problem.

[mir]

Further findings;
1)   This grey component is found to be a temperature dependent resistor such as thermistor or PTC (posistor), thus normal to have the resistivity of 50kR is quite normal.
2)   Mine and two other Fluke 179s (F179) show an identical symptom, that is the mode always in resistance mode regardless of the selection. The ohm (Ω) symbol is always shown regardless of the mode selection. This is also confirmed by the observation that the U1 (SL10327) analog front-end IC’s current source output (pin 36) is putting out approximately 9V (pules) to the Ohm plug as the F179 is in ohm mode.
3)   The microcontroller U2 (M430F) is keep sending 9 bytes of control signal to U2 through SPI port. The timing of this code transmission is seems coincide with the 9V pules and the beeping.

[retiredcaps]

Hmm, same symptom from 3 users in different parts of the world from the simple act of changing a battery.

At this point, I would suspect a firmware bug?  As I asked before, yet no one has mentioned, what pcb board is this?

As a bonus, list the firmware version by using the power up option by pressing hold + VDC.  This may not be possible if the MSP430 is in a funny state.

If everyone has the same pcb revision and firmware, then you can give this information to Fluke and possibly get a warranty replacement?

[rsjsouza]

Perhaps short the battery contacts for several minutes to be sure the MSP430 is not locked in a weird brownout state? That would be my best bet.

Another idea is to put a battery that is measuring as close to 9V as possible. Battery quality has been all over the place and I wonder if some 9V ones have been measuring too high for the meter to be comfortable. That is a much less likely scenario, though.

[Andy Watson]

Perhaps the fault is not due to a low battery, but due to the supply to the processor failing. For example, by a decoupling capacitor becomming short or low resistance. There's a suspicious looking tantalum in the above photo!

[mir]

The mode selection is determined by selecting one of the resistor divider taps from 1 through 7. For each resistor divider taps, the modes are assigned as [1]  AC-V , [2]  DC-V , [3] DC-mV , [4] Ohms/Cap , [5] Diode Test , [6] AC-mA , and [7] AC-A. The selected mode is connected to U2’s pin 5 (analog input, SWPOS, P6.6).
When the mode switch is at OFF, U2’s DC supply is shorted between VCC (+0.8V) and DGND (-2.5V) by the mode switch, at the same time the 9V battery is disconnected by the DC switching P-MOSFET.  Thus U2’s state should be cleared every ON-OFF power cycle even if U2 is in into unknown state. DC supply rails (+2.5V, +0.8V, -2.5V) and 0V (GND) were generated by three LDOs.  All DCs are working solid. Some of the DC-rail decoupling capacitors were checked. Push and hold “HOLD” switch while the mode switch is turned from “OFF” to “AC-V”, all the letters and symbols appear on the LCD display. Then number “2.02.5” is displayed for about 1sec after releasing “HOLD” switch.  This may be an error number?

[mir]

F179 PCB revision number: Rev 015

[Khaveer]

Are there any signs of battery leakage? I've encountered a couple of different Fluke meters with similar symptoms that suffered from leaky batteries.

[retiredcaps]

Then number “2.02.5” is displayed for about 1sec after releasing “HOLD” switch.  This may be an error number?

2.02.5 is your firmware revision.

[mikec]

For what its worth I have a fluke 179 which I purchased in mid 2009.

It has

Firmware Version: 2.03.5
Hardware Version: fluke 17x-3011 rev 015

I have changed the battery in this meter at least once and I've never seen the problem reported here.

[mikec]

Maybe as suggested previously it is worth opening the meter:

http://mrmodemhead.com/blog/fluke-77-iv-copper-corrosion/

The very last paragraph describes something similar and the comments section is very telling about a common corrosion issue with these series of fluke meters (77-iv has the same PCB as 179 and 177 afaik btw)

Can't explain why changing the battery would trigger the above scenarios though

[mir]

1.   Mode input
Since the F179 is appeared to be always in resistance mode, U2’s mode sensing SWPOS voltage is lowered by temporally added resistor, but this did not affect the symptom what so ever. The mode selecting voltage divider resistor network picture was posed previously.
2.   TPS77050 LDO input voltage of 5.69V
TPS77050 is providing the total of 5V (+2.5V and -2.5V). Based on 87-V schematic that the majority of components are very similar as F179, specified that the “Low battery” status threshold is set at 5.69V.
5.69V = (845k+226k)/226k*1.2V. Two resistors 845k and 226k are the voltage divider to provide 1.2V threshold voltage. These resistors can be found between “HOLD” and “MINMAX” push button pads.
If this threshold is true for F179, 5.69V is the below the TPS77055 minimum requirement of 6V input. Therefore at 5.69V or lower DC supply is a possible to set F179 in unstable condition.
3.   There was no evidence of battery leakage in my case.
4.   So far, all findings are pointing towards firmware issue(s) as mentioned by “retiredcaps” earlier.