URGENT! My Fluke 187 multimeter stopped reading voltages (ac and dc) - Page 1
Forum section: electronics / repair

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 01:45:08 am
content: Hi there,Pretty much it. I was checking some high DC voltages in an amp I'm building (around 450V) and suddenly it stopped reading, went to test a 1,5v battery and nothing, changed the selector to mV and it gave me the correct reading.What is happening? how can I fix this? I really need this multimeter working right now.I'll appreciate any help.Thank youGuy.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 24, 2017, 03:07:32 am
content: 1. Post clear focused pictures of both sides of the pcb.2. With no probes attached and rotary dial set to DCV, what does the lcd display?3. With probes attached and shorted and rotary dial set to DCV, what does the lcd display?4. With probes attached, what does the lcd show when you measure a 1.5V cell (in your description, nothing means nothing to us - that is, what does the lcd show)?5. Do you have another meter to make measurements?

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 05:28:56 am
content: Quote from: retiredcaps on June 24, 2017, 03:07:32 amHi Retiredcaps,Here are the answers:1- Pictures attached2- 0.0000 VDC and the +/- sign changes very fast back and forth from + to -3- Same as before4- If I move the probes the numbers jump around from say 0.0020 VDC to 0.0200 VDC and when I measure the cell it goes to 0.0001 VDC stays there for a while and then drops to 0.0000 VDC +/- sign same as before5- This is the only meter I have but tomorrow I might borrow one from a friend.Just found out that if I measure a cell with the mV DC setting it actually measures the cell correctly but then once the probes are off the value keeps being displayed and then it drops VERY slowly.Let me know if you need anything else.Thanks a bunch.

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 05:31:42 am
content: More pictures

author: Twoflower
author_rank: Frequent Contributor
timestamp: June 24, 2017, 08:56:01 am
content: Can you also post a picture of the rotary switch (the side that goes tot he PCB) please. The slow 'decay' might indicate a problem with the contacts.The tracks on the contact fields looks reasonably worn. Can you also check if they are still intact. As of not worn through the metal to the FR4.

author: alm
author_rank: Super Contributor
timestamp: June 24, 2017, 09:51:25 am
content: Some of the switch contacts look very worn to me. To the point that I am wondering of there was sufficient lubrication on those contacts. Based on the symptoms (something seems open near the voltage divider), and the conditions (measuring a fairly high voltage), I would also look for open fusible resistors. If you have access to another DMM, I would also measure the resistance across the input terminals while the 187 is in various ranges. Should be 10 MOhm, but it would not surprise me if it was much higher, if not open circuit, on most ranges.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 24, 2017, 10:20:19 am
content: check all the power resistors, the bridge rectifier, and the gray smt near the input plugs, i dont know if its a bead / ferrite / inductorMaybe search for a 83 87 series dmm schematics, easily found on the web, it should give you some ideas or hints ??For the 187 189, you have a calibration manual on the web, it gives input impedances and current on different inputs ...

author: oldway
author_rank: Super Contributor
timestamp: June 24, 2017, 10:44:46 am
content: Quote from: The Guy on June 24, 2017, 05:31:42 amI am not a specialist and I have no service manual, nor schematics of this multimeter.....But the 1K resistance at the right side of the PCB seems to be a fuse resistor....did you check it ? How much is his resistance ?If you don't have another multimeter, you could solder a 1K resistor in = only to check if it works again or not.If it works, replace the fuse resistor by another one from Fluke for safety.

author: oldway
author_rank: Super Contributor
timestamp: June 24, 2017, 12:01:22 pm
content: Be very carefull with this....9V is too high voltage to play testing circuits of a multimeter...you can "kill" an IC and destroy your multimeter....

author: alm
author_rank: Super Contributor
timestamp: June 24, 2017, 12:19:21 pm
content: Fine, I've removed it.

author: oldway
author_rank: Super Contributor
timestamp: June 24, 2017, 12:50:19 pm
content: Quote from: alm on June 24, 2017, 12:19:21 pmRemoving your post, you turn my message impossible to understand.....that's an unfair practice on a forum.Now i am obliged to quote all your posts, what will use a lot of space on the forum. This is nonsense....

author: JFJ
author_rank: Regular Contributor
timestamp: June 24, 2017, 02:16:28 pm
content: Quote from: The Guy on June 24, 2017, 01:45:08 amYou may find this blog helpful:http://mrmodemhead.com/blog/fluke-87-fusible-resistor/

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 03:43:28 pm
content: Quote from: JFJ on June 24, 2017, 02:16:28 pmPhew!! ...yup, that seems to be the problem. Pretty much the symptoms my fluke has. Will check that resistor in a while, gotta go to my friend's shop to borrow another dmm.I was so scared that the chip was fried!Thank you. Will report back.(Btw, the connections in the rotary switch are perfect. Those like "grooves" that appear in the picture are a visual effect caused by the polished surface.) thanks everyone!

author: ModemHead
author_rank: Frequent Contributor
timestamp: June 24, 2017, 05:26:04 pm
content: Quote from: alm on June 24, 2017, 09:51:25 amSeems like a good observation to me, esp. the bolded part. Usually for a Fluke meter, the first section of the voltage divider resistor network is the 10 Meg "top" part of the divider. In millivolts configuration, the downstream side of the 10 Meg is grounded by the analog processor, providing the expected 10 Meg input impedance, while the ADC input is taken from the ohms/diode sense path. If something is open in this 10 Meg-to-ground path, it might explain the "decay" response, and the lack of response in Volts mode. This path would include switch contacts, the resistor network, and the analog processor itself.Edit: changed my mind about the fusible resistor, it still might be open.

author: Ian.M
author_rank: Super Contributor
timestamp: June 24, 2017, 05:42:43 pm
content: So you suspect the 1K 2W fusible resistor next to the board edge, but don't have another multimeter to check it with. Patch in an ordinary 1K resistor directly across it and see if the meter reads correctly. If so, order a suitable replacement, if not remove the extra resistor and look elsewhere for the fault.However*DO* *NOT* *USE* it on any *VOLTAGE* *ABOVE* *50V*until you have replaced it with the proper resistor or an appropriately rated equivalent.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 24, 2017, 08:22:17 pm
content: Quote from: The Guy on June 24, 2017, 05:28:56 amHere is where having another meter, even a free Harbor Freight one, helps. The HF should be able to measure if the fusible resistor is open or not or close to 1k ohm. I wouldn't use the HF on the 450V amp as it might fail in more unpredictable ways, but for unpowered resistance measurements, it works fine.BTW, you should also check the blue MOVs which should measure 0L (infinite) resistance. The black PTC, just above the fusible resistor, should measure around 1.1k ohm. All measurements can be done in-circuit. If the MOVs or PTC don't measure as expected, then remove them and verify out of circuit.edit: The 187 is one of my favourite meters.

author: EHT
author_rank: Frequent Contributor
timestamp: June 24, 2017, 08:41:01 pm
content: With all due respect The Guy, it seems like you are a beginner? Fine for fixing the meter, but your main project haslethalvoltages in it. I suggest you gain more experience on some low voltage circuits first - under 50V, nothing connected to AC line supply.If you proceed with your high-voltage project my advice is get some insulated croc-clips, say like these (rated 600V or more):http://www.fluke.com/fluke/uken/accessories/Test-Leads-Probes-and-Clips/AC175-Alligator-Clip-Set.htm?PID=76067Then, when testing the voltages on your amp, clip the meter to the circuit you want to measure with the AC powerunplugged, then turn it on safely away from the circuit. Make sure the case/isolated side of the PSU of the amp is earthed. Also note that the PSU Caps may hold charge for a while, especially if the amp isn't working and thus not drawing any current. You may wish to measure that so you know how long you need to leave it to discharge before touching it.Once you proceed beyond testing the power you will really need a scope too.Best of luck!

author: Ian.M
author_rank: Super Contributor
timestamp: June 24, 2017, 08:56:58 pm
content: +1.In addition to EHT's advice above, if there isn't a good, secure place to clip the + lead to for the measurement you need to make, and a good ground point for the - lead, solder a little loop of tinned copper wire to ther track, pad or terminal to provide a reliable secure connection point.If there are any nicks or other damage to your meter's leads, replace them. When ordering meter accessories, ONLY buy from the manufacturer or a major authorised distributor - its critically important for your safety to avoid buying possible fakes from EBAY.If you end up having to do any signal tracing in your amp, not only will you need a scope, you will also need a scope probe with an adequate voltage rating - at least Cat II 600V. Most switchable x1/x10 and many x10 probes will be unsafe to use on a valve project with a 450V supply rail.

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 10:18:51 pm
content: Quote from: EHT on June 24, 2017, 08:41:01 pmThanks EHT,I am in fact a beginner, but I've been studying tube amp related electronics AND safety measures for almost a year now, and I think I am getting the hang of this. Recently I built my first guitar amp and it is playing like a charm. No hum at all and AWESOME sound! The only problem I have right know is a crackling noise in one of the channels.This meter circuit and some of the components are new to me though.I still need to borrow or buy me another DMM, today couldn't get one because caught the flu. Sucks.

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 10:22:29 pm
content: Quote from: Ian.M on June 24, 2017, 08:56:58 pmHey there, thanks for the tips. A scope is definitely on my listThat copper ground loop is installed, I already figured that out when I was looking for a good and secure anchor for my ground lead

author: The Guy
author_rank: Regular Contributor
timestamp: June 24, 2017, 10:30:37 pm
content: Quote from: retiredcaps on June 24, 2017, 08:22:17 pmHi Retiredcaps,The 187 is a great meter! Has everything I need.I already installed a 1.5K resistor over the 1k fuse resistor (didn't have a 1k) and nothing happened. Will test what you suggest as soon as i get another DMMCheers

author: retiredcaps
author_rank: Super Contributor
timestamp: June 25, 2017, 04:02:26 pm
content: While you are waiting to get another meter and recovering from being sick, does resistance mode work at all?Does the meter show 0L with no probes attached when set to resistance mode?Does the meter show 0.2 ohms with probes attached and shorted when set to resistance mode?

author: The Guy
author_rank: Regular Contributor
timestamp: June 25, 2017, 04:12:51 pm
content: Quote from: retiredcaps on June 25, 2017, 04:02:26 pmYep, yep and yep.... With probes attached and shorted it displays 0.13ohmI just performed some fuether tests and it reads current, temperature, diodes and capacitance, it didn't read an 0047uf cap though it only displayed a flashing OL. But it did read an 047uf no problem.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2017, 04:28:39 pm
content: Hard to believe that sub 500VDC would do anything to your meter assuming it was in the DCV mode.Did you manual range the meter to make sure you did not take out an attenuator stage and the meter is just hunting now? You may need to try a few different ranges.It would be funny if it was one or more attenuator stages and you had the meter in something other than DCV mode when the HV was applied. I damaged my TPI meter this way and took out two attenuator stages.I understand they have a life time warranty. Personally, I would have just sent it in to service.

author: The Guy
author_rank: Regular Contributor
timestamp: June 25, 2017, 04:41:45 pm
content: Quote from: joeqsmith on June 25, 2017, 04:28:39 pmI am possitive it was on VDC auto range. In manual range it doesn't read anything right now. It just displays 0,0000Will call to the service tomorrow and see if there is some kind of warranty.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 25, 2017, 04:56:37 pm
content: Quote from: The Guy on June 25, 2017, 04:41:45 pmRead the terms and conditions of Flukes "lifetime" warranty in the 187 manual or online. If they determine you abused it due to high voltage, they will not give you free service/replacement.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2017, 05:04:49 pm
content: You may need to test more than one range with more than one test voltage or maybe you have. 0,0000 may be the lowest range.

author: The Guy
author_rank: Regular Contributor
timestamp: June 25, 2017, 08:02:35 pm
content: Quote from: joeqsmith on June 25, 2017, 05:04:49 pmYup, i tried all different ranges. Will test with different voltages also.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2017, 08:12:47 pm
content: If it behaved the same for all the ranges, I doubt that's going to be it then. Not that it would have helped you.

author: BMack
author_rank: Regular Contributor
timestamp: June 25, 2017, 08:41:03 pm
content: FYI, this is why you ALWAYS need a backup meter. Admittedly, my 8 backup Flukes are overkill but you should at least have one, preferably one at work or in your car.BTW, that crackling in amps is often just a dirty pot(s).

author: retiredcaps
author_rank: Super Contributor
timestamp: June 25, 2017, 10:34:57 pm
content: When you get a working meter, measure the input impedance of the 187 when it is set to DCV and turned on. It should be around 11M ohm. See attached picture.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 25, 2017, 10:38:49 pm
content: The sometimes free with coupon Harbor Freight meter only measures up to 2M ohm so it would be useless in the above test. In addition, it wouldn't help measure a MOV either as a MOV could measure 4M ohm and be bad, but the Harbor Freight meter only goes to 2M ohm.

author: The Guy
author_rank: Regular Contributor
timestamp: June 27, 2017, 07:37:56 pm
content: Quote from: retiredcaps on June 25, 2017, 10:34:57 pmokey dokey, bought a cheapo meter and measured all i knew how to measure.The input impedance reads "open"the metal film and carbon comp resistors read OK, that black 1ohm resistor also reads ok... I mean, all those resistors have their values within spec.

author: The Guy
author_rank: Regular Contributor
timestamp: June 27, 2017, 07:47:01 pm
content: Quote from: retiredcaps on June 24, 2017, 08:22:17 pmBlue MOVs read open. The black PTC reads 1.14k ohmWhat's that red thingy at the side of the PTC? ...because it reads 100Kohm more or less.

author: The Guy
author_rank: Regular Contributor
timestamp: June 27, 2017, 08:32:33 pm
content: Please feel free to chime in guys... read my last two post and let me know if you have any ideas.Thanks.

author: The Guy
author_rank: Regular Contributor
timestamp: June 27, 2017, 09:21:09 pm
content: I'll be damned.... I seem to have found the problem! I did just read this thread:https://www.eevblog.com/forum/testgear/fluke-18718987-iv-help-needed/...and my fluke has the very same failure. Resistance is open between those same two pins in the voltage divider resistor network.Dang, that's a whole lotta money to fix because it requires re-calibration it seems...Any ideas? can I repair it myself? ...i'm not sure how to desolder that resistor network...Why Fluke? Why?

author: The Soulman
author_rank: Super Contributor
timestamp: June 27, 2017, 10:09:20 pm
content: You sure that is open and not aprox. 10Meg.?Sure your meter can read that high? (most cheapies don't)

author: The Guy
author_rank: Regular Contributor
timestamp: June 27, 2017, 10:20:55 pm
content: Quote from: The Soulman on June 27, 2017, 10:09:20 pmYep, i'm sure, this cheapie (us$40) can read up to 200M ohm

author: retiredcaps
author_rank: Super Contributor
timestamp: June 27, 2017, 10:37:05 pm
content: Quote from: The Guy on June 27, 2017, 09:21:09 pmDo you have a 10M ohm resistor that you can solder like in the other thread to see if the meter works?If not 10M, try a 1M ohm. The values will be off, but we are just testing it to see if there is any other damage.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 27, 2017, 10:39:45 pm
content: Quote from: The Guy on June 27, 2017, 10:20:55 pmWhat did you buy for $40? Make and model please.

author: MosherIV
author_rank: Super Contributor
timestamp: June 27, 2017, 10:44:37 pm
content: QuoteYou can check by measuring between each leg of the divider network. If it really broken, there will be an open circuit between a pair of legs.I am affraid there is no cheap fix.You can either sell the meter off for parts or look for one being sold for parts.You can download the service manual which tells you how to calibrate the meter but you will need some special equipment or some way to generate the voltages AC and DC, resistances and currents.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 12:03:59 am
content: Quote from: retiredcaps on June 27, 2017, 10:37:05 pmI have a 1M resistor but it's a very fine resistor for hifi audio... I don't want to waste it. Will need to buy some for this test.The $40 dollar multimeter is a mexican distributed made in china unit, it's a Truper model MUT-39. Not accurate at all... like 1% of error in voltage readings. But hey, it does the work, and I just finished measuring the amp that killed my beloved Fluke. This cheapo did it like nothing, felt like measuring potatos... Lol.After this experience no more flukes for me I guess... way too expensive for this kind of failure. My next multimeter it's gonna be a Hioki...or maybe you guys can suggest me some good ones?

author: tooki
author_rank: Super Contributor
timestamp: June 28, 2017, 07:27:06 am
content: Did Fluke decline to service it under warranty? Or are you just assuming it, even though there's no reason to assume they'll decline it?

author: Armadillo
author_rank: Super Contributor
timestamp: June 28, 2017, 08:18:15 am
content: Quote from: The Guy on June 28, 2017, 12:03:59 amSpeed of Measurement/ADC.How is the speed for Truper? I think the unit is in Number of measurement per second.You know, in repair, can't weight for the display to take its time to answer.I think is a fluke accident for this FLUKE, would you say?.

author: MosherIV
author_rank: Super Contributor
timestamp: June 28, 2017, 08:59:09 am
content: I do not understand how the resistor divider network got damaged without the other input protection components being taken out first.The OP has not given the history of the meter, so we do not know if the meter was miss-treated before he got it.QuoteThis assumes the OP bought the meter and is still the 1st registered owner.

author: tooki
author_rank: Super Contributor
timestamp: June 28, 2017, 02:30:06 pm
content: In theory. But there are countless reports of Fluke repairing/replacing meters under warranty with no proof of purchase whatsoever, e.g. with ones found in dumpsters. That alone makes it worth looking into even if you technically aren't eligible. I'm just astonished that the OP doesn't appear to have even attempted that route and has instead written off Fluke altogether. (See their other thread where they're looking for a new meter and have sworn off Fluke forever. In it, they also indicate that they were the original purchaser.)Their reluctance to attempt warranty service, and the fact that the supposed circumstances of the damage are well within the operating specs (never mind overload specs) of the meter make me skeptical of the actual cause of damage; what really happened, OP?

author: tooki
author_rank: Super Contributor
timestamp: June 28, 2017, 02:37:27 pm
content: Quote from: MosherIV on June 27, 2017, 10:44:37 pmIn the other thread about a broken divider network, someone said it cost around $30 for the part from Fluke. How is that beyond economical repair???

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 02:51:08 pm
content: Quote from: tooki on June 28, 2017, 02:30:06 pm...i did ask for a rapair under warranty at the fluke representatives in my country and since I didn't bought the multimeter in their store they basically told me to F. Off. Their customer support is poop.What really happened? I already explained what really happened.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 03:08:59 pm
content: Quote from: tooki on June 28, 2017, 02:37:27 pmBecause the repair require recalibration and here they would charge me like 400usd for the whole package and I'm not going to dump 400bucks in this dmm if it is going to suck like this again at some point.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 03:14:18 pm
content: Quote from: Armadillo on June 28, 2017, 08:18:15 amIt's very fast, but not precise and it will jump around. For example when measuring 340vdc it will show the value like in 3sec but then will jump from say 338vdc to 445 back and froth like forever, so you need to calculate the average value yourself.EDIT: Sorry it's not 445, it's 345, it would jump from 338 to 345.

author: MosherIV
author_rank: Super Contributor
timestamp: June 28, 2017, 03:39:28 pm
content: QuoteWhat about getting the part from Fluke, someone said it is only $30, fix it yourself.Then get another calibration Lab to re-calibrate the meter. You need to make it clear it is a Calibration adjustment and not just a calibration check.The cost of that depends on the local cal lab.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 03:49:51 pm
content: Quote from: MosherIV on June 28, 2017, 03:39:28 pmThat's actually a good idea, will try to find a small lab that will recal my meter. Not sure if I'll find one though, but if i do that'd be great.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 28, 2017, 04:20:57 pm
content: Quote from: The Guy on June 28, 2017, 03:14:18 pmIf one can trust themeter's manualpublished CAT ratings, it seems it will be enough for lower voltage jobs. The bouncing around in voltage measurement can possibly be due to either cables or something internal. Put it in continuity mode and see if the buzzer is intermittent or continuous as you move the cables around: if intermittent, replace the cables and see if the problem goes away; if the buzzer is continuous, the issue may be located at the voltage measurement circuit.If the Truper meter was purchased new, I would go back and try to get a replacement/discount/refund.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 04:36:13 pm
content: Quote from: rsjsouza on June 28, 2017, 04:20:57 pmSorry, my mistake. The jumping would be from 338 to 345, not to 445. Will go to the store where I purchased it and try another to see if it's "normal" or not

author: The Soulman
author_rank: Super Contributor
timestamp: June 28, 2017, 06:30:29 pm
content: Why not replace/bridge the +/- 10 meg resistor with another (decent quality) 10 meg and ad a trimmer network to itthen you can adjust yourself.If it reads good on one range than all others should read good also, replacing the entire network could be more troublesome.It's a bodge but it's better than nothing.

author: Armadillo
author_rank: Super Contributor
timestamp: June 28, 2017, 07:05:24 pm
content: Quote from: The Guy on June 28, 2017, 03:14:18 pm3 sec is way too slow. I think for fluke is probably 300msec per reading, 20,000 counts to 99.99%. That would be the only reason I am using Fluke, not so much on the safety CATegories. Money for Quality as the saying goes. It's like a F16 vs Mitsubishi Zero. If I can remember correctly fluke is not using the 7106 chip, I think its some custom ASIC chipset.When you repaired the Fluke, make a comparison. I don't think the china one can compare.

author: Ian.M
author_rank: Super Contributor
timestamp: June 28, 2017, 07:20:35 pm
content: Quote from: The Soulman on June 28, 2017, 06:30:29 pmBecause on higher voltages the open circuit resistor could flash over or leak giving a highly inaccurate reading. If you do this, you need to locate the defective resistor element on the substrate, and grind it away so it can never shunt the replacement resistor.

author: The Guy
author_rank: Regular Contributor
timestamp: June 28, 2017, 10:49:07 pm
content: Quote from: Armadillo on June 28, 2017, 07:05:24 pmDude , it's a friggin 40 dollar meter... I don't know, I eyeballed it maybe it's 1 sec or 10 who knows. All I'm saying is that it got the work done. I'm pretty sure a japanese toyota will outlast a mercedes big time.Obviously I'm not keeping this meter for checking high voltages because I might get killed... I just bought it to check my screwed up fluke

author: tooki
author_rank: Super Contributor
timestamp: June 29, 2017, 08:00:43 pm
content: Quote from: The Guy on June 28, 2017, 02:51:08 pmSo talk to Fluke USA (or whatever country you purchased it from) and see what they say. If they're willing to cover it under warranty, then the postage is still likely to be cheaper than the repair.As for why I am skeptical of your story: you measured something well within the capabilities of the meter. There's no way that should have caused the damage shown.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 29, 2017, 09:11:53 pm
content: I have repaired a Fluke 8060A that had an intermittent connection in one of the pins of the Caddock resistor divider. In my case it was not an electrical damage but instead a mechanical one - I suspect that either the meter was subjected to a fall or someone had tried to repair it and accidentally hit the resistor divider. I fixed it by re-soldering the pin to the pad on the ceramic substrate.If the multimeter of the OP was subjected to mechanical stress and the connection was hanging by a hair, the higher voltage measurement may have been enough to thermally vapourize what was left of a connection. I would, in this case, get a very potent loupe and carefully inspect the resistor divider for any problems.

author: The Guy
author_rank: Regular Contributor
timestamp: June 29, 2017, 10:19:57 pm
content: Quote from: tooki on June 29, 2017, 08:00:43 pmAll I can say is that I am not lying. I was measuring 4 different caps all with 450VDC in one of their leads and when I measured the third (without changing the selector) it didn't read crap. So. There.Now if you still don't want to believe me then to my eyes, damn, kind of stubborn man.

author: The Guy
author_rank: Regular Contributor
timestamp: June 29, 2017, 10:35:53 pm
content: Quote from: rsjsouza on June 29, 2017, 09:11:53 pmI inspected the R divider with a 10x magnifying loupe but didn't see anything weird.... what should I look for?

author: The Guy
author_rank: Regular Contributor
timestamp: June 29, 2017, 10:58:52 pm
content: May someone please point me to the resistor network I need to buy? maybe a Caddock? I'm not sure how to find it.I attached a picture from the original.Thanks.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 29, 2017, 11:00:58 pm
content: Quote from: The Guy on June 29, 2017, 10:35:53 pmIn my case it was a very small crack on the solder between the pad and the pin. I would also try to inspect the ceramic substrate for any very thin cracks. Something similar to what Dave did in a salvaged oscilloscope where the front panel suffered a hit (sorry, I forgot the episode number)

author: The Guy
author_rank: Regular Contributor
timestamp: July 01, 2017, 03:35:13 am
content: Quote from: rsjsouza on June 29, 2017, 11:00:58 pmChecked the resistor network closely and couldn't see anything suspicious (I'm a high end jeweler, so I have a keen eye).Weird.The problem now is how to find a new resistor network, can't find it. Called to the fluke representatives here and they told me that since the 187 model is long ago discontinued they do not sell the part anymore. Searched the caddock site but couldn't find the part either.Maybe someone can give me a hand? I'll appreciate it greatly.Thanks

author: Electro Detective
author_rank: Super Contributor
timestamp: July 02, 2017, 02:24:15 am
content: I reckon with a bit of surfing there'll be some Ebayers out there with parts available,or flogging physically damaged meters sold as partsMight be able to score a working board cheaper than stuffing around sourcing parts and gambling,and avoid any more of those classic 'sorry that model is obsolete, **** off and buy a new one..' Flook serviss fone calls we all love..

author: Armadillo
author_rank: Super Contributor
timestamp: July 02, 2017, 04:07:47 am
content: Quote from: joeqsmith on June 25, 2017, 04:28:39 pmUnclamped Flyback maybe? Or damaged wheeling diode.If its straight DC voltage, then its a fluke accident.

author: Electro Detective
author_rank: Super Contributor
timestamp: July 02, 2017, 07:22:05 am
content: Whether it's a Fluke, Flook, Brymen, Uni-T or Harbor Frightmeter,if you're prodding inside a tube filled gadget, then a high voltage probe or some form of attenuation is a must haveSHTF is best read as a peaky 100 volts, rather than a nano burst of 10000v +++

author: tooki
author_rank: Super Contributor
timestamp: July 02, 2017, 07:13:48 pm
content: Quote from: The Guy on July 01, 2017, 03:35:13 amStop dealing with the dipshit local distributor and talk to Fluke directly. (I run into the same stonewalling with distributors in Switzerland. So I talk to the manufacturer itself, and then they force the local guys to do what they're supposed to.)

author: MosherIV
author_rank: Super Contributor
timestamp: July 02, 2017, 07:26:03 pm
content: Fluke would not sell me parts direclty in UK. I had to go through their authorized parts distributors.Ask or look uo who are Fluke parts distributors in your country.Alternatively, ebay for a spares or repair one.Another alternative, you know which pins are open circuit, carefully measure to see if you can find where the break is. If you are lucky, it might just be where the pin joins the board and you may be able to reflow it or use silver paint to re make the connection

author: Armadillo
author_rank: Super Contributor
timestamp: July 02, 2017, 08:40:27 pm
content: Quote from: Electro Detective on July 02, 2017, 07:22:05 amIf it's a burst, wouldn't it be better to verify other functions of the meter right after the resistor network........ before buying the network?Do you think other parts will sustain that kind of a K.O. blow, particularly the ASIC?

author: Electro Detective
author_rank: Super Contributor
timestamp: July 03, 2017, 01:50:32 am
content: My point is whether or not it's a fixed and verified 100% working Fluke 187, or a higher Cat rated Brymen or Amprobe etcwhen poking around in tube gear or TV circuits or similar it's a better bet to have an attenuating probe or circuit of some sort, rather than risk taking out either an expensive meter or a 'basic' sacrificial cheap cannon fodder meter (which may survive better lol) due to a fast unforeseen transient, or pulsed signal/s exceeding the meter's dynamic rangei.e. I have no problem during a troubleshoot if my meter indicates 4.5v or 45v in the presence of 450v using an attenuator,same deal when using add on clamp meters, 1ma = 1 amp etc

author: Ian.M
author_rank: Super Contributor
timestamp: July 03, 2017, 04:51:37 am
content: Why would you expect meter trouble making measurements with a 1KV DC rated meter and probes in circuits with supply rails up to 500V? Linear circuits, even with inductive loads wont have more than double the supply voltage at the waveform peak. I'm assuming you aren't *STUPID* so don't try to measure the collector, drain or plate voltage of chopper circuits and class C amplifier stages, or break the circuit to a large inductor carrying significant DC current while the meter is across it. Of course one also needs to take adequate care of your own safety but this discussion is already way off track into the long grass . . . ..On the rare occasions we needed to measure voltages over about 800V in the repair shop, our first recourse was the Avo 8 which had a 2.5KV DC range, or for over 2KV we had a dedicated EHT meter that read up to 25KV. By not pushing the limits of our meters' ratings, we never killed any Flukes or even lesser meters due to overvoltage. Unless you repair CRT scopes, arcade monitors or the like, or work on HVDC power devices and circuits, with the commercial death of the conventional CRT, one seldom needs the capability to measure voltages above one KV any more.

author: Electro Detective
author_rank: Super Contributor
timestamp: July 03, 2017, 06:18:30 am
content: I am familiar with all those drills, and have an AVO 8 mkV for the higher 2 KV stuff that has a pop out breaker if things get nastyOP states the meter rated at 1000v Cat 111 got fried at 450 volts, maybe not because of the meter but because of a fault or something amiss in the DUT.If OP goes back in to the same scenario with a new or fixed meter, he may be back here again at this post a lot poorer.This is why I suggest he may want to invest in some attenuation

author: Armadillo
author_rank: Super Contributor
timestamp: July 03, 2017, 06:30:03 am
content: He did say, blue MOV read open.Linear amp section we all know unlikely, but switch mode section possible especially how the 450v is generated? Is it common voltage in USA?OP said 3rd capacitor... no ideal if the caps are in cascade or the actual part of the amp circuit involved or how 500vdc is generated?Anyway, likely is a defective resistor array network but fluke lifetime warranty is effectively 10 years, or 7 years from end of manufacture.It is worthy to note that fluke qualifies that protection devices can be impaired, this implies from previous owner likely. Probably that's why the need to establish original ownership.in any case, it would not be wise to say that blue MOV read open to them.

author: The Guy
author_rank: Regular Contributor
timestamp: August 19, 2017, 09:58:39 pm
content: Just wanted to let you know for future reference that I just installed a Kaddock 10Mohm 1% resistor I ordered over the broken resistor network and my dear Fluke 187 multimeter is working like a charm again!!! So awesome. Not sure how accurate yet, but I compared some measurements with the cheapo multimeter and it's perfect, also measured some good quality caps and resistor and reads also perfect.I thought I'd lost the fluke.So, thanks fellas!Take care.

author: Ian.M
author_rank: Super Contributor
timestamp: August 19, 2017, 10:22:19 pm
content: The problem with that is unless you effectively disconnect the broken section of the resistor network (with enough clearance to withstand 1KV) you can never trust the meter again as if you use it on higher voltages, the break in the resistor network may flash over and leave a partially conductive path. If it does that, it will, in parallel to the Kaddock resistor, drop the total below 10Meg and cause the meter to over-read.

author: The Guy
author_rank: Regular Contributor
timestamp: August 19, 2017, 10:56:44 pm
content: Quote from: Ian.M on August 19, 2017, 10:22:19 pmI am aware of that... I don't have a high voltage source at hand, but I did measure 220Vac without any trouble. If it happens that an arc gets formed through the broken resistor network I will gouge away right above the main leg the resistance substance, like 0.5mm wide to make sure no arc is formed as you suggested. Thanks.

author: Ian.M
author_rank: Super Contributor
timestamp: August 19, 2017, 11:04:46 pm
content: If you can, crop and desolder the 10Meg leg of the module and add a sliver of Kapton tape over the stub of the leg to increase the separation.

author: The Guy
author_rank: Regular Contributor
timestamp: August 19, 2017, 11:48:48 pm
content: Quote from: Ian.M on August 19, 2017, 11:04:46 pm...or maybe just cut the leg altogether and solder the kaddock leg on the pcb instead

author: Ian.M
author_rank: Super Contributor
timestamp: August 19, 2017, 11:52:03 pm
content: That's what I meant - remove the leg, add extra insulation because the clearance may be insufficient for 1KV and connect the replacement resistor to the PCB pads.

author: The Guy
author_rank: Regular Contributor
timestamp: August 19, 2017, 11:57:58 pm
content: Quote from: Ian.M on August 19, 2017, 11:52:03 pmoh... ok, yea good idea