Bricked Fluke 177 - Page 1
Forum section: electronics / testgear

author: andyB2022
author_rank: Regular Contributor
timestamp: July 14, 2022, 08:07:54 pm
content: Hi!My Fluke 177 doesn't want to work any more. The idiot me just tried to measure it own current draw from it's own 9V battery via the 400mA range.... Bodged some cables around the battery connector tried to test the current, had no luck, placed back the battery and now it's dead...I know I'm an idiot...Do you guys know any solve for this? The microcontroller seems to work as the full display is lit while pressing the HOLD Key, PoFF and LoFF seem to work too...Please watch the video below to better understand...https://youtu.be/1-nA6hS6c2E

author: Per Hansson
author_rank: Unknown
timestamp: July 14, 2022, 08:58:44 pm
content: Sorry to hear that, you can take a look at these threads, might be some valuable information in them for your case, especially the first one:https://www.eevblog.com/forum/testgear/fluke-177-failed-and-need-support-to-repair/https://www.eevblog.com/forum/testgear/dmm-reading-it_s-own-battery-voltage-low-voltage-detection/https://www.eevblog.com/forum/testgear/fluke-87v-_bricked_-when-probing-own-battery/

author: andyB2022
author_rank: Regular Contributor
timestamp: July 14, 2022, 09:33:18 pm
content: Thank you for your tip. Looks like the DMM is pure trash.... such an expensive mistake...

author: Per Hansson
author_rank: Unknown
timestamp: July 14, 2022, 10:34:15 pm
content: I would inspect each component with good light under magnifying glass, if you are lucky there will be some external component that took the damage and saved the ASIC.There was at least one example provided in the first thread.And you know the EE mantra: tho shall measure voltages!

author: andyB2022
author_rank: Regular Contributor
timestamp: July 14, 2022, 10:36:58 pm
content: I've checked all regulators, I have (referenced to GND battery) 2.5V 3.3V 5V, all steady...One thing that caught my attention was the bridge rectifier than on the AC side is open, and on DC side measures 1.7V which seems okay. (Out of circuit of course)Also reading the first thread I can't find the -2.5V supply.

author: Fungus
author_rank: Super Contributor
timestamp: July 15, 2022, 12:58:38 am
content: I'll point people to this thread when they ask why anybody needs more than one multimeter.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 09:35:44 am
content: So far the only questionable part I could find is this bridge rectifier which has the AC side open. After removing it from the board, the meter has no reaction to this "change". Can anyone tell me on their DMM what voltage drop does the bridge have?Update: -2.5V rail on AD737J is present in reference to COM on the board (not battery's GND).

author: tom66
author_rank: Super Contributor
timestamp: July 15, 2022, 09:53:51 am
content: If you look at the diagram for a full bridge rectifier it will be apparent why it tests open on the 'AC' side. There is no path for DC, it is like a bunch of valves that reverses the connection on each mains cycle.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. Maybe 3V for instance. Then the ADC can measure voltages above and below COM potential.If what you did is to either short COM to battery ground, or to +9V, then it's very likely that the reference will have been damaged.Unfortunately on many meters this reference does in fact come from the main ASIC.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 09:58:29 am
content: So we can consider the meter dead right? Replacing the FPGA from another meter would cost as much as a new one...

author: tom66
author_rank: Super Contributor
timestamp: July 15, 2022, 09:59:40 am
content: I would wait for some others to confirm as I am not an expert in Fluke meters but I think it may be that way unfortunately.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 15, 2022, 01:40:21 pm
content: Quote from: tom66 on July 15, 2022, 09:53:51 amNot sure about the 177, but on the 87, COM is 2.5V above battery -ve, as the -2.5V supply is at battery -ve. I would not be surprised if the 177 is very similar. I'm not aware of a service manual for the 177 but the one for the 87 found in those other threads might give you some pointers as to where to look.One thing I would say about measuring your supply voltages, is don't just measure them at the regulator, measure them at the IC's they are powering too.

author: Wrenches of Death
author_rank: Regular Contributor
timestamp: July 15, 2022, 01:53:45 pm
content: Quote from: Fungus on July 15, 2022, 12:58:38 amYep!Sadly, this isn't the first post that I've read over the years of someone frying their meter trying to read the voltage of the internal battery.It might be worth posting a warning about attempting to do this as a permanent sticky.WoD

author: AVGresponding
author_rank: Super Contributor
timestamp: July 15, 2022, 02:26:33 pm
content: Quote from: Wrenches of Death on July 15, 2022, 01:53:45 pmThis had me wondering if there was anything specific to this in the manual; there isn't, at least in the 80-series one. The closest to it is this:"• Make sure the battery door is closed andlatched before operating the Meter.• Replace the battery as soon as thebattery indicator (M) appears.• Remove test leads from the Meter beforeopening the battery door."But this is under the general warning about avoiding shock risks etc, which I guessmightlead people to think if they aren't measuring any dangerous voltages it's ok to ignore the warning.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: July 15, 2022, 02:30:04 pm
content: see the photo from this thread:https://www.eevblog.com/forum/testgear/fluke-177-failed-and-need-support-to-repair/?allcheck voltages on the pins of the 16-pin chip labelled "24351". this is the analog-to-digital converter, an LTC2435-1:https://www.analog.com/media/en/technical-documentation/data-sheets/24351fc.pdfwith the F177 set to DC VOLTS, input leads shorted, and using pins 14, 15, 16 as your ground point, you should see:3.3v on pin 2 (supply for the ADC)2.5v on pin 3 (reference voltage)0.0v between pins 5 and 6 (in+ and in-)report back the voltages returned, as well as what is on the F177's LCD.cheers,rob :-)

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 03:43:11 pm
content: You mean shorting COM and Voltage plugs on the DMM and then doing those measurements? Meter set to V DC or mV DC? Will try the measurements and come back with some updates.In my opinion, if it was a problem with the ADC, the meter would work normally just it won't be able to measure anything correctly...but it doesn't even want to "cycle" to different measurement options when I spin the dial.Also if you guys have an ideea of what IC I can remove from the PCB and then test the meter without it, I'll try it... nothing to lose right now...Regardless of the screen, it's still the same as in the video of the first post. Wherever the dial is set it will stay in continuity mode and will beep sometimes randomly like it would detect a dead short on a PCB / wire etc.If anyone can tell me the input impedance of their meter between V and COM? I measure 2.5M ohms with a crappy UNI-t...

author: tooki
author_rank: Super Contributor
timestamp: July 15, 2022, 04:26:06 pm
content: Quote from: andyB2022 on July 15, 2022, 09:58:29 amASIC, not FPGA. An FPGA is a very different type of device.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 04:28:00 pm
content: Thanks for pointing out, my bad

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 04:44:51 pm
content: Quote from: robert.rozee on July 15, 2022, 02:30:04 pmWith input leads shorted (V and COM) we have:Pin 2 4.962VPin 3 2.5VPin 5 2.5VPin 6 2.5VAll measurements referenced to pin 14,15,16 of the ADC.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 15, 2022, 08:12:02 pm
content: Small update, I've tried to measure all possible things on the board and mark them on a photo. All measurements in white font are referenced to the GND marked with the Bright Green circle in the middle. V and COM on the multimeter input jack were shorted during this measurement as one of you guys suggested above.Measurements with the orange line pointing at the values with white background and orange text are referenced to bright green GND too.On AD737 I took the two -Vs +Vs measurements against it's 8'th pin which should be GND according to the datasheet. As you can see here I've noticed something really strange in +Vs side, a fluctuation between 2.459 - 4.95V.After other measurements around the board I came back to this AD737 and the fluctuation was gone.... steady 2.459VHope the pic will help you guys better understand...

author: alonsojar
author_rank: Contributor
timestamp: July 15, 2022, 09:03:04 pm
content: Hello, my 175 (I assume is the same meter except the lack of led light) in DC position shows 11M Ohms between V and Com measured with a 87v.Good luck !!J. Alonso

author: AVGresponding
author_rank: Super Contributor
timestamp: July 15, 2022, 09:54:26 pm
content: Do you have access to an oscilloscope? It might be instructive to observe whether there is activity on the ADC pins 12 and 13. It doesn't matter about decoding it, just seeing if there is activity there or not would be useful.

author: BeBuLamar
author_rank: Super Contributor
timestamp: July 15, 2022, 10:01:22 pm
content: I hope you get it fixed. I have a 175 that needs new case as the built in yellow hoslter is a mess.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 16, 2022, 11:25:00 am
content: Here are the DSO captures for :LTC2435As far as I know about SPI, SCK signal doesn't look good...(pin 13)

author: andyB2022
author_rank: Regular Contributor
timestamp: July 16, 2022, 03:20:11 pm
content: Better shots on this oneYellow is SDO pin 12Blue is SCK pin 13

author: AVGresponding
author_rank: Super Contributor
timestamp: July 16, 2022, 06:44:50 pm
content: Well, it looks as though the ADC is alive and outputtingsomething. Is the signal path to the Fluke ASIC intact?

author: andyB2022
author_rank: Regular Contributor
timestamp: July 17, 2022, 09:01:17 am
content: How can I check that? I don't have any datasheet on the pins of the ASIC... I've probed something yesterday around some vias for the ASIC but found nothing....

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2022, 10:29:23 am
content: Unfortunately the only way is to trace it out the hard way... as you've found, with it being a multi-layer board it's a difficult proposition.The 8x series uses the same ADC, its connections to the main ASIC are:Pin 11CS(ADCS*) --> ASIC ADCS*Pin 12 SDO (D-OUT) --> 49k9 resistor --> ASIC D-INPin 13 SCK (ADSCK) --> ASIC ADSCKObviouslyCSshould be over rather than under-scored, but that's not so easy to do here...The resistor in the data line will make it harder but not impossible to identify the pin on the ASIC.Now, on the 8x series, the main ASIC is the main signal processor and also the display driver; I don't know if this is the case with the 17x series. If they are separate, the symptoms could indicate a dead MSP ASIC, with the display driver outputting those dashes as a kind of default in the absence of instructions.Before any of that though, can we recap on some earlier measurements? If the ADC is meant to be getting 3.3V and it's getting 5V that's not good. In the 8x series the ADC is supplied with +/- 2.5V, the REF andVINare connected to GND. It would be useful to know which is correct for your case.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2022, 10:39:35 am
content: Quote from: andyB2022 on July 16, 2022, 11:25:00 amIt's hard to say whether any of the overshoot might be artifacts of the measuring setup. Here's the excerpt from the 8x service manual on the ADC operation:Analog to Digital ConverterU3 is a 20-bit Σ∆ analog-to-digital converter (ADC). C21 & C22 are power-supplybypass capacitors. The DC signal at FE_O (U1 pin 19) provides the signal input for U3.The reference for conversion is supplied by U8 as described in 1.3 to the REF and VIN*(compliment of VIN) inputs. Since REF* (compliment of REF) is tied to -2.5 V and bothpairs of inputs to U3 are handled differentially, the dynamic range of the VIN is ±1.25 Varound COMMOM. The microprocessor U2 uses three digital lines to communicate withU3. U3 signals the microprocessor U2 that a conversion is completed by pulling the SDOsignal line to logic low (-2.5 V), which is coupled through current limiting resistor R31to DOUT. When U2 is ready for the reading, it pulls ADCS* of U3 to a logic low andclocks the data serially out of SDO with the signal ADSCK applied to SCK. ConnectingF0 of U3 to -2.5 V sets the internal clock so that the normal mode rejection ratio(NMRR) of the digital filter will provide adequate rejection of both 50 Hz and 60 Hz.I've left the Fluke typos intact...

author: andyB2022
author_rank: Regular Contributor
timestamp: July 17, 2022, 12:15:09 pm
content: Quote from: AVGresponding on July 17, 2022, 10:29:23 amREF- is the only pin tied to GND.VCC pin has 5V on it (datasheet says between -0.3V to 7V)REF+ 2.5VIN+ 2.5VIN- 2.5VAll display related traces come exclusively from the microcontroller, most of them are on the top layer. So the ASIC has nothing to do with dispaly (I guess).

author: andyB2022
author_rank: Regular Contributor
timestamp: July 17, 2022, 04:11:14 pm
content: I've found a great offer for around 16$ shipped to my country (Romania, Europe) for the ADC and ASIC chips.The question is, may it work with those things new? (I know meter will need recalibration).

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2022, 05:07:37 pm
content: Quote from: andyB2022 on July 17, 2022, 12:15:09 pmI'll go out on a limb and suggest that those voltages are correct.

author: Fungus
author_rank: Super Contributor
timestamp: July 17, 2022, 05:09:38 pm
content: Quote from: andyB2022 on July 17, 2022, 04:11:14 pmIt's worth a shot at that price if you have the equipment to replace them.

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2022, 05:41:11 pm
content: I'd be reluctant to condemn the ADC without further testing, but if you can easily afford the parts, and if as Fungus mentions you have the tools to replace them I can see no harm.A couple of things would be useful to know.1. Could you sketch a quick drawing to show how exactly you connected it up when you tried to measure the current draw.2. Is there a Fluke ASIC for switching the front-end ranges, like there is in the 8x series? Given your reported input impedance of 2-ish megohms, when it should be 11, I'd want to look more closely at this first.If the MSP is getting bad/no data from this ASIC it might explain why it appears functional using some of the buttons but doesn't respond to the rotary switch properly, as the front end ASIC and not the MSP is the one directly connected to the rotary switch and the range function buttons.Granted, I'm guessing a bit here, based on the 8x series design, but I think it's reasonable to suppose they'd use a generally similar system architecture, as it would save time and therefore money during the design stage.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 17, 2022, 06:03:23 pm
content: Here is the way I did the thing, of course first time I saw nothing on the display and decided to swap the testing leads in between them... it was too late anyway as first time I connected the GND of the battery to COM lead...As I've read here on the forum, the COM lead is very low impedance (like DSO GND) and you've gotta be really careful where you place it. Probing just with the V+ lead would be harmless (impossible to measure current without COM of course, as my intention was...)I have a hot air soldering gun, flux, solder wick... I've soldered even smaller packages, so no issues here.The only idea would be not to damage even more things while replacing the ADC and ASIC. Even if the ADC seems fine, it's worth ordering that thing too, just in case.But, I have a stupid question here, the ASIC comes already programmed, doesn't it? I know these things can do only one task... from Bitcoin miningp.s. The idea of the whole topic is to try to fix those things and help other people... I could just go and buy a new meter and that's it, learn my expensive lesson, but that won't make the forum interesting, wouldn't it?

author: Fungus
author_rank: Super Contributor
timestamp: July 17, 2022, 07:08:47 pm
content: Quote from: andyB2022 on July 17, 2022, 06:03:23 pmASICs aren't programmable, their functions are hard wired. It's like building a fixed-function computer out of 74-series logic chips instead of a CPU+MEMORY. They can also incorporate some analog elements in there as well.Disclaimer: I'm sure there's some ASICs out there that have a programmable section of the chip and also some FPGAs with built-in opamps and comparators.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 17, 2022, 07:11:17 pm
content: Thank you for that intel. I'll order the ASIC and the ADC. Keep you guys posted with this.Meanwhile is it a good idea to just desolder the current ASIC and power on the meter without it? See if the behavior changes in any way?

author: AVGresponding
author_rank: Super Contributor
timestamp: July 17, 2022, 09:22:40 pm
content: Quote from: andyB2022 on July 17, 2022, 07:11:17 pmAre you talking about the MSP? That is to say, the Linear Technologies Fluke chip N23297? I suspect you won't cause any extra damage by doing this, though I am leaning very much in the direction of a front-end issue rather than the MSP. I also suspect the behaviour will not change much if at all, as without this chip in circuit it won't be able to send any signals to the display driver, which will probably default to the same dashes.The MSP ASICmaycontain a small eeprom for the calibration data.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 18, 2022, 01:44:50 pm
content: Could you please define "front-end"?Recalibrating the meter won't be an issue as I have near me a specialized center that can perform this. As I've talked already in the idea of service with the guys out there, they've said that if the meter is too away from a calibration (having too big "errors") they won't be able to perform it as the meter will refuse storing new values (this explanation from them seems very odd to me)...

author: AVGresponding
author_rank: Super Contributor
timestamp: July 18, 2022, 04:44:21 pm
content: By front-end I mean the analogue circuitry and the range dividers and switches. On the 8x series, the range switching though partly controlled by the rotary switch, also is largely controlled by an ASIC, which in terms of the signal path, sits between the input jacks and protection circuits, and the ADC.So the complete signal flow (simplified) would be, input jacks --> protection circuitry --> rotary switch --> range + signal conditioning ASIC --> ADC --> Microprocessor.I don't know if the 17x series does it the same or a similar way. A good look at both sides of the main board might help us figure that out.

author: Per Hansson
author_rank: Unknown
timestamp: July 18, 2022, 04:53:48 pm
content: Quote from: AVGresponding on July 17, 2022, 05:41:11 pmandyB2022: I would also look into what AVGresponding asked above, as Alonso tested you should have 11M input impedance but it is 2.5M on your unit.The unit itself can switch from 11M down to 10M when you press the range switch (if the processor is working that is).In the attached schematic of a Fluke 77-III I traced the VDC input path in red for you (I take no responsibility for any mistakes I've made)The classic failure is one of RT1, R1 or RV1, RV2, RV3 fails in a input overload scenario, and then the input impedance will change.We know in your case this is not what happened, so we can rule out those components, along with the high precision Z1 reference ceramic network.So basically the path I show we can assume is ok, but if you see you can also trace other paths from that into the front end, to some comparators.If those are bad then you could be reading a lower input impedance, this is just an example to give you some ideas what to look for.P.S: Please understand that the attached schematic is for the older model Fluke 77-III but some parts should still be similar!Source:https://dam-assets.fluke.com/s3fs-public/77iii___smeng0100.pdf

author: andyB2022
author_rank: Regular Contributor
timestamp: July 18, 2022, 05:07:33 pm
content: I owe you guys some apologies, the 2.5M resistance was measured with a very dodgy meter, I've got this UNI-T 216C from a friend today to test again. Looks like the resistance between COM and V is infinite (above 60M at least, the maximum this clamp meter can measure)...Second photo is to proof that the clamp meter measures correctly (tested it on a few 10k resistor too to make sure...)So basically we are dealing now with an open circuit...

author: Per Hansson
author_rank: Unknown
timestamp: July 18, 2022, 05:36:56 pm
content: The meter must be switched to the DCV mode to measure the input impedance.Here an example of two meters:Code:UTE61E:AN8009:OFF:25.60M36.4M1V:11.15M10.982M10V:10.13M10.085M100V:10.04M9.995M1000V:10.03M9.985M

author: andyB2022
author_rank: Regular Contributor
timestamp: July 18, 2022, 05:43:21 pm
content: Please watch below video with sound to hear to buzzer. I pressed on the case to show you that the meter it's alive.https://www.youtube.com/shorts/pdBuUkCJIhM

author: AVGresponding
author_rank: Super Contributor
timestamp: July 18, 2022, 05:57:37 pm
content: That's quite odd behaviour; normally when you can affect things by for example pressing on the case, it's a bad connection issue. The microprocessor seems to be cycling ranges; the impedance readings on V are what you might see with a constant range cycling. Have you inspected the leaf contacts on the rotary switch?You need to set your clamp meter to read voltage when you check the resistance/continuity/diode functions.

author: andyB2022
author_rank: Regular Contributor
timestamp: July 18, 2022, 06:17:49 pm
content: The screws are not in the case that's why I've had to press on it, as I open it and put it back very oftenly nowdays (so the LCD makes contact and shows you guys something).The leaf contacts are in pristine condition, so are the gold plated traces under them (just so you guys understand how much the meter was used it doesn't even have scratches caused by the contacts from many "switches" between different measurements).

author: andyB2022
author_rank: Regular Contributor
timestamp: August 17, 2022, 06:53:25 am
content: Parts came in. Replaced ASIC and ADC, no change in it's behavior...That means that those parts were ok?

author: AVGresponding
author_rank: Super Contributor
timestamp: August 17, 2022, 04:30:16 pm
content: Most likely, yes, unfortunately.

author: andyB2022
author_rank: Regular Contributor
timestamp: August 18, 2022, 09:50:19 am
content: I guess there is something wrong in the front end as you said previously.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 18, 2022, 11:24:57 am
content: Tracing it and drawing it out will be an exercise in patience and concentration...

author: andyB2022
author_rank: Regular Contributor
timestamp: August 18, 2022, 11:53:13 am
content: 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?

author: EEVblog
author_rank: Unknown
timestamp: August 18, 2022, 01:07:18 pm
content: Quote from: tom66 on July 15, 2022, 09:53:51 amYes, most meters will be like this.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 18, 2022, 05:01:46 pm
content: Quote from: andyB2022 on August 18, 2022, 11:53:13 amI wouldn't worry too much about the possibility of losing traces in the multilayer board here, the analogue stuff before the ADCshouldbe 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.

author: Ugur
author_rank: Regular Contributor
timestamp: August 19, 2022, 10:26:15 am
content: 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.

author: andyB2022
author_rank: Regular Contributor
timestamp: August 27, 2022, 01:35:16 pm
content: 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.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 27, 2022, 07:05:00 pm
content: 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 28, 2022, 08:57:36 am
content: Quote from: andyB2022 on August 27, 2022, 01:35:16 pmWhat happened to the famous "lifetime warranty"?Quote from: andyB2022 on August 27, 2022, 01:35:16 pmWhy? A Brymen is much cheaper and easily as good.

author: BeBuLamar
author_rank: Super Contributor
timestamp: August 29, 2022, 10:43:35 am
content: Since the OP doesn't live in the USA then the Brymen may make sense.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 29, 2022, 12:18:47 pm
content: Quote from: BeBuLamar on August 29, 2022, 10:43:35 amAre the Greenlee branded Brymens horribly overpriced or something?

author: BeBuLamar
author_rank: Super Contributor
timestamp: August 29, 2022, 12:43:53 pm
content: Quote from: AVGresponding on August 29, 2022, 12:18:47 pmYes 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.

author: Fungus
author_rank: Super Contributor
timestamp: August 29, 2022, 04:04:26 pm
content: Quote from: AVGresponding on August 29, 2022, 12:18:47 pmYes.(Well, it depends on their support network, which I know nothing about. Do they give you a lifetime warranty?)

author: electr_peter
author_rank: Unknown
timestamp: August 29, 2022, 09:10:19 pm
content: It's not the first time Fluke 177 damage from "self measurement" had been mentioned in this forumfluke-177-failed-and-need-support-to-repairMost DMMs are not designed to measure their own battery voltage with probes. Also, manuals recommend to remove probes when changing batteries. See topicdmm-reading-it_s-own-battery-voltage-low-voltage-detectionfor discussion and more sad cases ofDMMs.

author: andyB2022
author_rank: Regular Contributor
timestamp: September 04, 2022, 06:12:29 pm
content: 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.

author: BeBuLamar
author_rank: Super Contributor
timestamp: September 05, 2022, 10:59:20 am
content: Quote from: andyB2022 on September 04, 2022, 06:12:29 pmThe 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.

author: boggis the cat
author_rank: Regular Contributor
timestamp: September 07, 2022, 06:15:26 am
content: Quote from: BeBuLamar on September 05, 2022, 10:59:20 amThey 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).

author: andyB2022
author_rank: Regular Contributor
timestamp: April 18, 2023, 11:48:56 am
content: 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 rangeI 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?

author: andyB2022
author_rank: Regular Contributor
timestamp: April 27, 2023, 07:45:14 pm
content: 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 0.145VVDC 0.45VmV 0.74VOhm 1.01VContinuity 1.31VmA 1.63VA 2.02VIn 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.

author: mwb1100
author_rank: Frequent Contributor
timestamp: April 27, 2023, 09:11:24 pm
content: 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 (fromhttps://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.

author: andyB2022
author_rank: Regular Contributor
timestamp: April 28, 2023, 06:57:36 am
content: Thank you for your reply, the buzzer is seeded correctly into its groove.