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

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 12:39:29 pm
content: my fluke 187(yes it is 187,not 189) after i replaced the lcd started to act weirdcan you suggest what to check on the board?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 12:41:58 pm
content: i checked the resistors,they seems fine but what are those blue and red ones? the bues are the mov-s(varistor) right? but what is the red one? and how to measure them?do i have to desolder them to measure?

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 12:46:40 pm
content: Did you clean the zebra strips while replacing the lcd ? Are they fitted in the correct position again ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 12:54:18 pm
content: i replaced the whole complete display assembly with a new one (thats why theres a 189 label on the front) so the zebra strips are new too

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 12:57:57 pm
content: ok but it seems that there are bad contacts to the display so I would reassemble the display and clean the zebra strips and the contacts on the board with alcohol

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 01:03:10 pm
content: why do you think theres bad connection to the display?the greyed out part on the second screen is the bar which is changing faster than the camera can catch up.the screen is fine as far as i can tell.but i cannot measure coltage with it,and it stays on at the off position,so there must be a problem with the dial terminals?(seems fine,not corroded or bent) or theres a blown component on the track somewhere but visibly theres no damaged part

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 01:09:54 pm
content: ok then I was on the wrong way , sorry .

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 01:41:58 pm
content: Can you anyway measure anything or is the multimeter completely locked up ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 01:46:39 pm
content: it seems it wont measure anything.the lead sockets seems fine too so i suspecting the movs or somehing around there but i dont know how to measure them or my another idea is the terminals in the knob.i disassembled it and i dont know if i put it back together correctly(maybe thats cause the off positions still on symptome)

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:05:37 pm
content: Ok that could be . Here in the forum there are teardown pictures of the 187 . Just look and compare it with yours . So you could perhaps find the fault

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:09:54 pm
content: i saw that pictures but they were too poor quality / the pics from the 87iv is different(the movs ect)

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:15:20 pm
content: Yes it s a quite different meter . Can you take some pictures of your multimeter and put it here in the forum ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:30:25 pm
content: not that different.99% the same.first i need some suggestions where to start.someone here must be saw that error before

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:37:31 pm
content: Well I unfortunately don t . So it seems that the processor locks up your multimeter . Did you put the old led back in to exclude the possibility that the new lcd is faulty and lock the multimeter ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 02:47:35 pm
content: the processor?what leads you to that conclusion?how can be the new lcd be faulty?it is clearly functioning / putting back the old one is pointless since it is broken

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:06:22 pm
content: well it could be possible that the new lcd locks up the processor so it doesn t measure anything and you cannot switch it off . I am not an expert in fluke multimeters . But in this case something let the multimeter not to work properly . If the movs or the ptc would be broken , you could measure it and you could switch off the multimeter properly . Another fault could be the contacts of the dial switch . Are they correctly fitted in ? Are the wipers in the correct position and not twisted 180 degrees ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:10:18 pm
content: how can be the new lcd block the processor? / the wipers can be misaligned since i tought that the pins are centered but as i look it closely it may be not so yes it can be twisted.do you have the correct pattern?or do you have a picture?the one i found here from it is too blurry

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:15:34 pm
content: ok here is one

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:18:00 pm
content: i saw this one.i cant see the orientation on it / how about the screen and the processor?

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:25:02 pm
content: Just click on the picture to enlarge it . Then you can see the orientation

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:26:33 pm
content: i did and still cant see

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:36:50 pm
content: look at the arrows

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:41:29 pm
content: lol,eagle eyesthe middle ones is twistedi did tried to swith all 180 degree before but never tought to try all possibilities.ill let you know the results

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:45:13 pm
content: they have to be in parallel line . if not then one is scratching on the pcb and not on the contact

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:47:24 pm
content: look

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:53:20 pm
content: they were parallel,just the middle ones were twisted 180 degrees

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:55:04 pm
content: ok does the multimeter work now ?

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:56:57 pm
content: i have to resolder the holder of the 10amp fuse first since it came off when i pulled the fuse out to check it

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 03:59:08 pm
content: Ok , shit happens

author: alext
author_rank: Regular Contributor
timestamp: February 18, 2017, 04:03:49 pm
content: yup,the third shit so farit starts to piss me off

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 18, 2017, 04:05:49 pm
content: Murphy s law again

author: alext
author_rank: Regular Contributor
timestamp: February 19, 2017, 11:42:09 am
content: it turns out that after i glued a tiny crack on the inside of the knob i assembled it together too fast and the superglue did not dried completely and the evapored glue made a tiny transparent insulating film on the mainboard connectorsit took hours to take it off with ipa / acetone but now it seems fully functionalnext time ill let the "instant" superglue sit for a few hours

author: WackyGerman
author_rank: Regular Contributor
timestamp: February 19, 2017, 12:48:44 pm
content: ok , so I wasn t that far away off with my thought of a problem with the dial switch . Hot glue would also work really well and colds down really quick . The main thing is you solved the problem

author: alext
author_rank: Regular Contributor
timestamp: February 19, 2017, 01:10:30 pm
content: yes i have hot glue gun but it is hard to dispense it precisely.mostly i use epoxy or super glue,usually it hardens within a minute,but the one i used last time(loctite super bond power flex) hardens in about 2 hours (without any caution about that on the package of course)