Fluke 287 DMM Teardown and photos - Page 1
Forum section: electronics / general

author: Baqar79
author_rank: Newbie
timestamp: June 28, 2011, 09:21:14 am
content: Just some exterior & interior shots of my Fluke 287 DMMHey thought I would try and sneak in a question as well; I cannot figure out why when selecting manual arrange above 50V (ie 500V & 1000V) I get a constant 3.0V AC regardless whether I short the leads or leave them disconnected; If I relative this value and measure small AC voltages the value given is pretty bogus (for example the 2V 1KHz output from the Rigol 1052E used for calibration becomes around 0.5V).

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: June 28, 2011, 01:25:59 pm
content: HiYou did a fine job with your Nikon D5000About the AC voltage ranges, yes there no zero volts,some DMM behave differently from others.For example the Fluke 28II at fresh boot, it shows some AC voltage in all ranges,and few minutes later it drops in to a minimum value.Its not a good idea to compensate the what ever volts shown in the display at the 1000V range,the measured volts will be accurately shown, no matter what.The most interesting picture for me, of the posted ones, are the one with the PCB,there is on it also the memory backup battery, so to retain date and time.Unfortunately such batteries, they live the most up to 8 - 10 years.At list in the digital cameras this is their life cycle.Thanks for posting.

author: Baqar79
author_rank: Newbie
timestamp: July 02, 2011, 01:38:21 am
content: I thought I might post the full resolution version of the main PCB as people seem more interested in this one.Thanks Kiriakos-GR for your response, I still feel a bit uncomfortable with the 3V voltage on AC (mind you it is about 0.3V on the 50V range as well), but it did come with a calibration report that said the 1000V was dead on. So for AC measurements relative is pretty much useless right?...Cheers,Jamie

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 02, 2011, 01:59:18 am
content: Quote from: Baqar79 on July 02, 2011, 01:38:21 amWell you made the mistake to get an TRMS DMM that sings special songs,normally you should get one with 15$ that shows all digits as 000 .Oh well, the next time you will do a better shopping ..

author: Unknown
author_rank: Unknown
timestamp: July 02, 2011, 02:34:58 am
content: Zeroing true-RMS voltmeters will increase your error. The RMS converter tends to be non-linear near 0V, which causes an offset at 0V input. It's usually calibrated at 100% and 10% of the range, to optimize the accuracy in this range. If you compensate for the offset, you shift the whole curve, which will cause errors for higher voltages. ACV is often specified above a certain part of the range (eg. 10%).Here is a blurb for Keithley explaining the issue.

author: Unknown
author_rank: Unknown
timestamp: July 02, 2011, 11:48:06 am
content: Great pictures Baqar79. And for anyone that wonders, the 289 is almost identical inside.

author: EEVblog
author_rank: Unknown
timestamp: July 02, 2011, 12:33:10 pm
content: Awesome pics.Ah, the good'ol LM324!Dave.

author: Astronomer
author_rank: Newbie
timestamp: September 25, 2011, 01:42:21 am
content: Thanks for taking the time to do the tear-down, take the shots and post them! They're sincerely appreciated.I was very curious about what's inside this DMM, and your post satisfied that curiosity. I received my 287 a week ago and I'd be in the doghouse if I took mine apart. I'm an amateur enthusiast. My hobbies all have many bits and pieces of electronics, and I felt it was high-time that I learned to troubleshoot the equipment as easily as I troubleshoot data networks. I'm fortunate in that a friend taught electronics at a community college for several decades and will mentor me as I stumble along.I'm a firm believer in not cheaping out when it comes to tools, and this DMM came highly recommended.Thanks again!

author: Richard W.
author_rank: Regular Contributor
timestamp: March 03, 2012, 09:01:51 pm
content: Quote from: Kiriakos-GRThats a double layer supercapacitor. EN-Type in the document.http://www.cde.com/catalogs/EDL.pdf

author: FenderBender
author_rank: Super Contributor
timestamp: March 04, 2012, 04:58:54 am
content: Quote from: Richard W. on March 03, 2012, 09:01:51 pmHence the C145 marking.

author: MerlinMac
author_rank: Newbie
timestamp: June 23, 2015, 07:12:02 am
content: Hi good morning, I have the multimeter flows 289 and I'm currently using with accessory IR3000 FC. In the application of mobile two locked me out options, you know why? Someone has disarmed the IR3000 FC? You give me some advice with 289 flows? A greeting and thank you very much to all.