Fluke 187/189 repair  - Page 1
Forum section: electronics / repair

author: Syzeryuino
author_rank: Contributor
timestamp: August 26, 2020, 11:53:38 am
content: I recently picked up a fluke 187 for 40$ from an online store in my country as not workingThe meter doesnt start up at all, after opening it i discovered one of the caps was blown(on the last pic), thinking it was an easy repair i replaced it. but it doesnt do anything, does anyone have a solution or a service manual of some sort for this meter?

author: aqibi2000
author_rank: Regular Contributor
timestamp: August 26, 2020, 11:56:41 am
content: What is the resistance across the points where you have installed the new capacitor?

author: daisizhou
author_rank: Super Contributor
timestamp: August 26, 2020, 12:05:21 pm
content: please checkhttp://bbs.38hot.net/forum.php?mod=viewthread&tid=853404&extra=page%3D1

author: Syzeryuino
author_rank: Contributor
timestamp: August 26, 2020, 12:14:26 pm
content: Quote from: aqibi2000 on August 26, 2020, 11:56:41 amIt was 1.1 Mega ohmQuote from: daisizhou on August 26, 2020, 12:05:21 pmOh wow didnt know this exist, thanks

author: daisizhou
author_rank: Super Contributor
timestamp: August 26, 2020, 12:18:59 pm
content: Check the manual carefully before repairing.

author: Syzeryuino
author_rank: Contributor
timestamp: August 26, 2020, 12:28:15 pm
content: Quote from: daisizhou on August 26, 2020, 12:18:59 pmthis might be asking too much at this point, but do you have the english version, my mandarin is really limited

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 26, 2020, 12:46:40 pm
content: There are signs of residue/corrosion mainly around the 93C56 and on both sides of PCB.I'd start with a good wash-down of whole PCB with toothbrush.Next start checking power supplies.

author: daisizhou
author_rank: Super Contributor
timestamp: August 26, 2020, 12:52:37 pm
content: Please use google translate.Just understand the circuit principle

author: daisizhou
author_rank: Super Contributor
timestamp: August 26, 2020, 01:00:08 pm
content: It is recommended that you use (washing water) to clean the motherboard, especially those with blue color corrosion, focus on cleaning!! Attention!! (Plate washing water) is not alcohol.It is a mixed liquid specially designed for cleaning PCB circuit boards.If you use alcohol, it will corrode the pads and other places and leave white marks. It is strongly recommended that you do not use alcohol to clean

author: kripton2035
author_rank: Super Contributor
timestamp: August 26, 2020, 02:49:16 pm
content: auto-translated documents in english

author: Syzeryuino
author_rank: Contributor
timestamp: August 26, 2020, 03:15:00 pm
content: Quote from: shakalnokturn on August 26, 2020, 12:46:40 pmok, will do!Quote from: daisizhou on August 26, 2020, 01:00:08 pmi dont think i have any of that, or they sell those things here, do you have an alternative like ethanol or wd40? or should i just wash it with water and let it rest in an oven?Quote from: kripton2035 on August 26, 2020, 02:49:16 pmwow man, thanks alot for that

author: joeqsmith
author_rank: Super Contributor
timestamp: August 26, 2020, 04:39:51 pm
content: During your attempt to repair the meter, how did you manage to damage this area?

author: daisizhou
author_rank: Super Contributor
timestamp: August 27, 2020, 12:40:01 am
content: It is recommended to use a knife to physically clear the black areaSeeing the PCBAfter seeing the PCB substrate layer thicknessStop after seeing the PCB base layerThen use insulating oil to protect

author: goaty
author_rank: Regular Contributor
timestamp: August 27, 2020, 07:31:06 am
content: Very interessting PDF with good points to start.I think you need to check from page 14 on the power supply first.Because your damaged cap is exactly at the power input.So that and the LT1307 etc are probably the thing to check.(Man I wish they would teach more english in China. It´s really hard to understand sometimes.)

author: Syzeryuino
author_rank: Contributor
timestamp: August 27, 2020, 07:43:22 am
content: Quote from: joeqsmith on August 26, 2020, 04:39:51 pmthe burnt pictures ( the small one ) is not mine but from the instructions , maybe its a fluke that's being serviced by the manufacterQuote from: daisizhou on August 27, 2020, 12:40:01 amok, i have cleaned the pcb and start probing around lt1307 and found that the voltage input of the lt1307 is ~100mv ( probably an error on the meter ) so my question is, what is the component between the photos? thanksQuote from: goaty on August 27, 2020, 07:31:06 amthanks for the advice, but i have the same question for you same as @daisizhou what's the component that cause that much voltage drop.

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 27, 2020, 07:57:24 am
content: The lowest component marked, the one with 6V on one side nothing on the other is an inductor to filter supply to the LT1307.If the inductor has fused consider the LT1307 may be damaged.

author: goaty
author_rank: Regular Contributor
timestamp: August 27, 2020, 08:05:08 am
content: You can for test bridge the inductor, but make sure not to use batteries but a current limited power supply !Later, maby I can try measure inductor in circuit if it is possible on my 189, so you can know the inductance.

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 27, 2020, 12:35:25 pm
content: I'm trying to imagine the abuse this meter has been through.There's a diode across the battery input I imagine it's only for reverse polarity protection.The fact that this tantalum capacitor and inductor before the LT1307 blew would point to an overvoltage, which would mean someone with a supply other than the normal batteries was careless.If you're lucky enough that happened before the person had time to wreck other things by scratching deposit between IC pins with the DMM powered...

author: joeqsmith
author_rank: Super Contributor
timestamp: August 27, 2020, 02:44:48 pm
content: Quote from: Syzeryuino on August 27, 2020, 07:43:22 amLOL. Yeah, I wasn't paying attention to who the posts were from.

author: goaty
author_rank: Regular Contributor
timestamp: August 27, 2020, 07:57:57 pm
content: The chip inductor on 189 measure in circuit 5 to 5,5µH.

author: Syzeryuino
author_rank: Contributor
timestamp: August 28, 2020, 05:43:06 am
content: Quote from: goaty on August 27, 2020, 07:57:57 pmthanks goaty ,after shorting the inductor for a split second the meter came to life!, ill look for replacement right away.Quote from: shakalnokturn on August 27, 2020, 12:35:25 pmi know right, just because fluke dmm are tough doesnt mean you need to abuse it like that. but this is pretty common in my country i guess. lots of fluke multimeter become black ( mine too before i wash it!).Quote from: joeqsmith on August 27, 2020, 02:44:48 pmhappens to all of us hahahah, just dont lost focus when fixing electronics!

author: goaty
author_rank: Regular Contributor
timestamp: August 28, 2020, 07:02:07 am
content: Quote from: Syzeryuino on August 28, 2020, 05:43:06 amThat doesn´t sound too good. So it died again ? Hopefully you limited the current...

author: Syzeryuino
author_rank: Contributor
timestamp: August 28, 2020, 01:20:24 pm
content: Quote from: goaty on August 28, 2020, 07:02:07 amsorry for phrasing it incorectly, i shorted it with twezers, and once it turned on i quickly pull it awayedit : was limiting the current to 300mA too much? it was on for less than a second.

author: Black Phoenix
author_rank: Super Contributor
timestamp: August 28, 2020, 01:30:12 pm
content: Quote from: Syzeryuino on August 28, 2020, 01:20:24 pmThe question is now to know how much current is present in that part of the circuit to know if you overshoot or not. But I think not, you just made a little "overclock".

author: Syzeryuino
author_rank: Contributor
timestamp: August 28, 2020, 06:57:35 pm
content: Quote from: Black Phoenix on August 28, 2020, 01:30:12 pmafter i replaced the broken inductor is it safe assume its fixed? like will it blow up if i put a battery in it? and the inductor that goaty identify is 5~5.5uH , can i use 5,7uH because its the only one i can find.

author: Black Phoenix
author_rank: Super Contributor
timestamp: August 29, 2020, 12:48:41 am
content: Quote from: Syzeryuino on August 28, 2020, 06:57:35 pmGo ahead, It is within tolerances. Fire the cute little guy and see what happens.

author: Syzeryuino
author_rank: Contributor
timestamp: August 30, 2020, 01:07:01 pm
content: Quote from: Black Phoenix on August 29, 2020, 12:48:41 amgood thing is it turns on!, but because of the very dirty zebra strips and the semi destroyed case the screen is very blurry!and when the screen turns on it keeps beeping and showing LEADS on the screen!, it was on volt mode and i already plugged in the leads, do you know why this happens?

author: coromonadalix
author_rank: Super Contributor
timestamp: August 30, 2020, 02:07:48 pm
content: Damn thats nastyBolt studs broken, the zebra strips seems crusty ...Hum are you sure the dial is at the right position(s) ? if yes the "LEADS" will show if your red lead is in the volt plug and you dial the Amp ... ma, ua selectionOr you still have a problem in it ?

author: Syzeryuino
author_rank: Contributor
timestamp: August 30, 2020, 07:15:11 pm
content: Quote from: coromonadalix on August 30, 2020, 02:07:48 pmyeah about the studs, i was planing to glue a standoff there and change the self taping screw to a machine screw.also about the dial, yeah its in the right position and it always shows "LEADS" in all the dials, but the logo in the top right corner does change

author: coromonadalix
author_rank: Super Contributor
timestamp: August 30, 2020, 07:44:10 pm
content: I repaired my one of my 189 stand off with the super glue and baking power mix, glued the stud, waited a few hours, put some baking power around the crack applied some glue and slowly rebuilt and solidifed the broken standoff i had, be carefull it stiffen really really fast.Be carefull to about the screws, they have a special thread, not the common ones, you may / surely create cracks, i've bought many original fluke screws.Maybe for the LEADS detection something is still wrong

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 30, 2020, 07:47:47 pm
content: On your LEADS problem:Did you take the green deposit on the PCB seriously and give a thorough scrub? If you didn't you could be looking for faults that aren't really there for a long time.If you have cleaned the PCB, look towards the banana sockets with detection contacts, you could have contamination in the socket itself or between plastic assembly and PCB.

author: Syzeryuino
author_rank: Contributor
timestamp: August 30, 2020, 08:55:03 pm
content: Quote from: coromonadalix on August 30, 2020, 07:44:10 pmok, this method seems more legit than planting a standoff myself!, but what is baking power? do you mean baking powder?Quote from: shakalnokturn on August 30, 2020, 07:47:47 pmafter looking at it the banana plug looks super crusty!, tried cleaning it with ethanol but that didnt fix it, i looked at the repair manual it says to soak it in IPA for 24 hours, so im doing that.

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 30, 2020, 11:01:50 pm
content: I'm not saying it'sthemethod but it works well for me:Spray the socket with contact cleaner then give it a "little of the old in-out, in-out" with a cotton ear bud.Repeat with new buds until they stop coming out grey.Have a sewing needle with a bent point at hand if you loose the cotton tip.

author: Syzeryuino
author_rank: Contributor
timestamp: August 31, 2020, 03:39:12 pm
content: after soaking it in 98% ipa it kinda looks more dirty now.. is that the dirt in the many layers of the board coming out? i tried cleaning it with ethanol and tooth brush to no avail

author: aqibi2000
author_rank: Regular Contributor
timestamp: August 31, 2020, 06:06:51 pm
content: Just do it