Bricked Fluke 177

[EEVblog]

I think the problem is that COM on a meter is not the same as battery ground,  it is going to be floating at some midpoint reference. 

Yes, most meters will be like this.

[AVGresponding]

Yeah, it's a bit out of my capability... An X-ray machine will do the job in seconds... Anyone here with something like that? Or maybe someone has a photo with the PCB already?

I wouldn't worry too much about the possibility of losing traces in the multilayer board here, the analogue stuff before the ADC should be reasonably straightforward. What might be slightly more tricky is the rotary switch; some of the traces from that might be quite sneaky, you might have to use one of the various "tricks" like a frayed test lead with your continuity tester to get broad coverage over a part of the board.

Don't give up hope, even if you have to put it to the back of a drawer occasionally. If you have some luck you might find a scrap one with a broken screen that can be used as a donor.

[Ugur]

If the asic is solid then there is only one possibility, the MSP main IC is faulty.
Is the device still under warranty? Because the warranty of these devices is LLTW (limited lifetime warranty), you can get support from an authorized service.

[andyB2022]

I bought the meter second hand (even tho was brand new) so no documents came with it. I've called an authorized repair center in my country and they told me that without some receipt / invoice when and where I bought it, they can't take a look at it.

I'll leave it in a drawer and check on it again when I'll have more time, for now I'm aiming towards an 87-V.

[AVGresponding]

Yeah, they will look to protect their bottom line. It would be nice if there was a service manual/schematic available. It's beyond my skills and patience to reverse engineer one.

[Fungus]

I bought the meter second hand (even tho was brand new) so no documents came with it. I've called an authorized repair center in my country and they told me that without some receipt / invoice when and where I bought it, they can't take a look at it.

What happened to the famous "lifetime warranty"?

I'll leave it in a drawer and check on it again when I'll have more time, for now I'm aiming towards an 87-V.

Why? A Brymen is much cheaper and easily as good.

[BeBuLamar]

Since the OP doesn't live in the USA then the Brymen may make sense.

[AVGresponding]

Since the OP doesn't live in the USA then the Brymen may make sense.

Are the Greenlee branded Brymens horribly overpriced or something?   

[BeBuLamar]

Since the OP doesn't live in the USA then the Brymen may make sense.

Are the Greenlee branded Brymens horribly overpriced or something?   

Yes the Green Lee are over priced and also they don't have all the models from Brymen. Besides I don't like rebranding products. I prefer to buy products from a company that makes them. I buy Green Lee punches but not meters. Besides if the OP lives in the USA he could have Fluke look at the 177 under warranty and only the serial # is needed. No receipt whatsoever. I know because I sent quite a few Fluke in for repair under lifetime warranty.

[Fungus]

Are the Greenlee branded Brymens horribly overpriced or something?   

Yes.

(Well, it depends on their support network, which I know nothing about. Do they give you a lifetime warranty?)

[electr_peter]

It's not the first time Fluke 177 damage from "self measurement" had been mentioned in this forum fluke-177-failed-and-need-support-to-repair

Most DMMs are not designed to measure their own battery voltage with probes. Also, manuals recommend to remove probes when changing batteries. See topic dmm-reading-it_s-own-battery-voltage-low-voltage-detection for discussion and more sad cases of DMMs.

[andyB2022]

I've got an used 87 V which I enjoy better, maybe because of more features and more accuracy...
Still miss the robustness and slimmer feeling of the 17x series.

[BeBuLamar]

I've got an used 87 V which I enjoy better, maybe because of more features and more accuracy...
Still miss the robustness and slimmer feeling of the 17x series.

The 87V is certainly a better meter than the 17x series. I do not see the 17x series as more robust than the 87x. The yellow cover of the 17x series tend to come off.

[boggis the cat]

I do not see the 17x series as more robust than the 87x. The yellow cover of the 17x series tend to come off.

They only come off if you get certain solvents/oils on the meter.

Customers that work with automotive or HV transformers tend to get the delaminating cover issue, but nobody else does.  They are oily/greasy to the touch, and require cleaning before you can calibrate them (let alone try to attach a label).

[andyB2022]

After some time I came back to the unit.

In the video below you can see how the impedance is changing between 4.2k and 0 ohms when the switch is on the mV. At the moment is changing the beeper beeps. VDC range has fixed 10M impedance and it doesn't move at all.

Here is the video:


If I try to measure the voltage between COM and V jacks, on mV range the voltage spikes up to 6.9V, on the VDC range none of that happens, the "voltage" there is 0V.

mV range


I have measured lots of things while comparing with the 87V schematics and most of the measurements are correct... Couldn't find anything that drew my attention.

The Fluke ASIC SL10327 has NO connections to the main microcontroller, only towards the 20bit ADC. Is that the way it needs to be?

[andyB2022]

Looking closely at the service manual for the 87V I've discovered that the two models share a lot of things.

One thing that really caught my attention is that the meter doesn't seem to know where the switch is positioned.

Broken meter:


Working meter with the switch in between 2 positions:


Here is the switch selection from 87V:


I could trace everything that you can see in the little diagram above except for one thing SWPOS (conected to PIN 5 on MSP). If I measure from pin 5 of MSP to meter GND (-2.5V in reference with COM) I get exactly 1M ohm but I can't find where that resistor is.
Since I couldn't find the resistor "R22", I wasn't able to trace the dirrect connection (if it is the same as the 87V) between pin 5 of MSP and contacts (perhaps switch pads) 15,19,23,25,23.

Now, comparing with a good working unit, if I measure from COM to pin 5 of MSP I get the following voltages:
VAC 0.145V
VDC 0.45V
mV 0.74V
Ohm 1.01V
Continuity 1.31V
mA 1.63V
A 2.02V

In between any swtich position I get 2.5V, which is right. I was hoping at first that on pin 5 I have permanent 2.5V and the meter doesn't know where the switch is positioned. Unfortunately, that came out false. All of the above voltages are present and match very closely on the good unit as well, so I still don't know what is wrong. Basicly, the voltage at pin 5 tells me that the meter is informed correctly about where the switch is positioned but it can't do anything about it.

[mwb1100]

When I tore down a 177 to take some photos for eBay, the selector didn't work when I put it back together.  It turned out that the beeper disc shown in the attached photo (from https://www.eevblog.com/forum/testgear/fluke-179-teardown-photos) had fallen out of it's recess and that was enough to make the selector act very strangely.  If you haven't already, make sure that disc is properly seated.

[andyB2022]

Thank you for your reply, the buzzer is seeded correctly into its groove.