Fluke 187/189/87 IV help needed - Page 1
Forum section: electronics / testgear

author: wictor
author_rank: Regular Contributor
timestamp: July 15, 2015, 10:03:02 pm
content: Hi,I have a problem in my fluke 187. It works in DC mV range, but not in normal V range. I think the problem is in voltage divider resistor network. The part has 626496 number on it. Input voltage comes to the first pin, but I cannot measure it after that. If I measure resistance between two first pins I get infinite resistance. Other pins give reasonable values. I have attached image of the part and I have marked pins, what I mean. Could someone measure resistance between these pins or do you know other source for information about this part?Thanks,Wictor

author: retiredcaps
author_rank: Super Contributor
timestamp: July 15, 2015, 10:12:05 pm
content: If you measure a 9V battery, what does the 187 show?

author: wictor
author_rank: Regular Contributor
timestamp: July 15, 2015, 10:33:43 pm
content: Quote from: retiredcaps on July 15, 2015, 10:12:05 pmIt shows 0 always in DC V range, no matter what the voltage is. Current measurement works from mA and A jacks. Resistance measurement works and mV range works. That's why I'm thinking that higher voltage range divider has broken.

author: Lightages
author_rank: Unknown
timestamp: July 15, 2015, 10:51:00 pm
content: Are you the original owner and is this fault from some abuse. If the answers are yes and no, then Fluke should be fixing this under warranty.

author: radioFlash
author_rank: Regular Contributor
timestamp: July 16, 2015, 03:13:20 am
content: I get 9.986 Megaohms between the indicated pins on my 187.

author: wictor
author_rank: Regular Contributor
timestamp: July 16, 2015, 04:13:12 am
content: Quote from: Lightages on July 15, 2015, 10:51:00 pmI'm not the original owner and I don't know what was the reason, why it broke.

author: wictor
author_rank: Regular Contributor
timestamp: July 16, 2015, 04:13:57 am
content: Quote from: radioFlash on July 16, 2015, 03:13:20 amThank you very much!

author: retiredcaps
author_rank: Super Contributor
timestamp: July 16, 2015, 05:30:10 am
content: Odd, those thin film resistor network are pretty reliable. I think I might have seen one post in the last 4 years about the resistor network not working?A couple of suggestions since you are not the original owner which means you unlikely get free warranty service/repair?First, try resoldering the second joint even if looks okay. Maybe there is a cold/cracked joint not visible to the eye?Second, trying soldering a 10M ohm resistor across pins 1 and 2, as a test, and see if DC volts work?

author: wictor
author_rank: Regular Contributor
timestamp: July 16, 2015, 06:31:38 am
content: Quote from: retiredcaps on July 16, 2015, 05:30:10 amI could see from the first two divider pins, that someone had already tried to solder those two... And since I measured infinite resistance that was most probably the reason why the meter didn't work. I also tried to resolder them after measurement. I don't see any cracks or other obvious reasons, why it have failed.I already tried 10M ohm resistor as soon I found out the value. The meter works with the 10 M resistor. Of course it's not spot on, but now I know there is hope to get it working again by replacing the divider and doing calibration. That might be too expensive though...Thanks all for your help!Wictor

author: retiredcaps
author_rank: Super Contributor
timestamp: July 16, 2015, 09:44:24 pm
content: Quote from: wictor on July 16, 2015, 06:31:38 amThe resistor network might be available from Fluke as replacement part. Even if you could get it, the cost of calibration is likely $60 to $100. Only you can determine if the parts + calibration check is worth the money.Another option is to try and find a 3rd party thin film resistor network (maybe from Caddock?). Again, you would probably have to check its calibration either yourself or pay someone to do it.Finally, you try to find a 10M ohm resistor that is 1% or better and just live with it knowing that it will be off its original specifications.

author: wictor
author_rank: Regular Contributor
timestamp: July 17, 2015, 08:50:39 pm
content: Quote from: retiredcaps on July 16, 2015, 09:44:24 pmIt's available and costs about 30 €.

author: Pulso
author_rank: Newbie
timestamp: October 04, 2015, 09:48:33 am
content: First I apologize for my English, actually is the google translator.A few days ago I bought a second hand Fluke189. It was with 1A fuse burned instead of the original 440mA. The most serious is that it measures twice as AC current. In measurements with 1-100uF capacitor failure. I have visually checked the PCB and all I've seen is a small bubble in the resistor array back with a x60 magnifying glass. It can result from the burning gases resistance.Can anyone tell me the measured among of all 626496 array pin values, can be found schematic or service manual?Quote from: wictor on July 17, 2015, 08:50:39 pmPlease Wictor, from where you bought the array?

author: retiredcaps
author_rank: Super Contributor
timestamp: October 04, 2015, 09:35:11 pm
content: Quote from: Pulso on October 04, 2015, 09:48:33 amThe precision resistor network is not required when doing a current measurement. The meter measures the voltage drop across the internal precision current shunt to get an ampere reading.Questions for you so I can make suggestions.1) Does DCV work in all ranges? 5V, 50 and 500V?2) Does ohms work in all ranges?3) Does ACV work when measuring mains?4) Does DC current work?5) Can you give us an example of double the AC current measurement?6) Does uA AC work?7) Does mA AC work?8] Does measuring a 1000uF capacitor work?9) Can we get clear focused pictures of your pcb? Both sides.