EEVblog 1592 - Fluke 287 Multimeter Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: January 11, 2024, 09:26:48 pm
content: Fluke 287 Multimeter Teardown

author: floobydust
author_rank: Super Contributor
timestamp: January 12, 2024, 12:44:59 am
content: Ahhh very nice. The transparent plastic appears to be needed for the jack-detect, IR opto-sensor passes through two jacks if you look carefully.The supercaps are discontinued and soon to be unobtainium. I believe it's the same supercap used in Fluke 189, 287, 289 - but not sure.07/2023 Elna is phasing out making coin supercaps, they are NRND but some production and stock available.Elna 0.2F 3.3V DSK-3R3H204T614-H2L new p/n is RSCSK2043R3D01004T. Mouser 555-DSK3R3H204T614H2Elna 0.33F 3.3V DSK-3R3H334T-HL new p/n is RSCSK3343R3D02008T. Mouser 555-DSK-3R3H334T-HL (thicker 2.1mm vs 1.4mm- fits)The second PTC RT2 might be for LowZ?Dave, please taunt Brymen to up their rotary switch tech instead of this "good enough" philosophy

author: golden_labels
author_rank: Super Contributor
timestamp: January 12, 2024, 04:44:16 am
content: Looking at the video, the clear plastic part completely covers the top side. Including the display. I suppose one wants to have transparent plastic over the display.As for the purposes, I may only come up with two ideas:Dust and water protection.It was cheaper/easier to make another part than to mold the case in just the right shape to hold all parts together.Quote from: floobydust on January 12, 2024, 12:44:59 amAnd then we learn that this idea is already patented. Or — the other end — Brymen won’t implement it, because they couldn’t treat it as their own IP.

author: Black Phoenix
author_rank: Super Contributor
timestamp: January 12, 2024, 04:49:34 am
content: Weren't the supercaps Panasonic? My 2007, first from the line batch of 289, was Panasonic until it gone to Fluke support because of the Supercar issue. Didn't disassemble after it so I don't know if it was replaced by a new Supercap or deleted entirely.Although new batch motherboards are equipped with lithium coin cell and holder.

author: floobydust
author_rank: Super Contributor
timestamp: January 12, 2024, 05:52:10 am
content: I think Panasonic was used but they discontinued their line up first, leaving Elna. I wonder what the power drain is, if a coin cell works.The Fluke rotary switch does have a few patents. 'Digital multimeter having enhanced rotary switch assembly'US 8093516andUS 8946571to show a couple.Brymen rotary switch a copy of a 1989Actron US patent US4876416.Another function of the clear plastic insert is passing IEC 61010 they wrap it in tinfoil to see if an arc can jump out to your hand, at the seams, LCD, buttons etc.You must have good HV isolation from the multimeter internals - PC board/battery holder to the outside case where your hand would be.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 12, 2024, 09:08:09 pm
content: The additional application processor with all the RAM really looks like huge overkill for such a multimeter. Almost makes no sense.

author: EEVblog
author_rank: Unknown
timestamp: January 12, 2024, 10:19:54 pm
content: Quote from: floobydust on January 12, 2024, 12:44:59 amAlso for the serial port.QuoteI was thinking of bodging in a replacement. I have a kit of various supercaps.QuoteWhat's their problem?Didn't they perform fairly well in Jow Smiths switch testing?

author: EEVblog
author_rank: Unknown
timestamp: January 12, 2024, 10:20:43 pm
content: Quote from: SiliconWizard on January 12, 2024, 09:08:09 pmMaybe they had used it in some other product?Works well enough from a low power point of view.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 12, 2024, 11:24:30 pm
content: Quote from: EEVblog on January 12, 2024, 10:20:43 pmYes, it's probably used in a whole line of products, and reusing the design is understandable. The MSP430 apparently implements the base measurement functionalities and most likely doesn't have enough resource left for implementing the UI and additional features of these more advanced models, so they did maximum reuse here and separated the two.It's perfectly understandable, but I can't help having a problem with products using a lot more resources than what's strictly needed to get the exact same features. It's just waste.The big bloat problem, it's everywhere, and the justification is always the same - that helps the company (or at least they think it does) by lowering immediate development costs, but it's otherwise a burden to everyone else, in the grand scheme of things. So that's my rant on "the great bloat".Quote from: EEVblog on January 12, 2024, 10:20:43 pmWell, no doubt it's perfectly usable and a nice product, but they claim a 100h min battery life, which is not horrible, but so-so. Sure could get significantly lower consumption with a less complex overall system by migrating what's done by the MSP430 in a recent, low-power 32-bit MCU and implement all the UI on it as well. You get the idea. Simpler BOM, simpler system, cheaper, much lower power.Now some companies do much worse in terms of bloat. Fluke is definitely still reasonable. They haven't used a 3GHz ARM SoC with 8GB of RAM to control a DMM with a monochrome display.

author: bdunham7
author_rank: Super Contributor
timestamp: January 12, 2024, 11:35:41 pm
content: Quote from: SiliconWizard on January 12, 2024, 11:24:30 pmYou're looking at an almost 2 decade old design for the meter and a bunch of obsolete chips. They've respun the board for the current versions and I have not seen at teardown on a new 287/289. I'd be curious, but not curious enough to peel the calibration sticker off of mine and take it apart.

author: scopeman
author_rank: Frequent Contributor
timestamp: January 13, 2024, 01:34:20 am
content: I still like my Fluke 37 and 77 series. 1000Hr life out of a carbon zinc battery. I would bet that a Lithium Iron battery like the Eveready Ultimate Lithium 9V would go a coupleof thousand hours or more.SamW3OHM

author: Black Phoenix
author_rank: Super Contributor
timestamp: January 13, 2024, 03:00:19 am
content: Quote from: floobydust on January 12, 2024, 05:52:10 amWell since it keeps date and time and some parameters and it is the only function of it, probably the same drain as a PC motherboard BIOS battery when 5vSB is not present.

author: EEVblog
author_rank: Unknown
timestamp: January 13, 2024, 10:19:21 am
content: Quote from: SiliconWizard on January 12, 2024, 11:24:30 pm200 hours life quoted while data logging.

author: EEVblog
author_rank: Unknown
timestamp: January 13, 2024, 10:20:41 am
content: Quote from: scopeman on January 13, 2024, 01:34:20 am

author: EEVblog
author_rank: Unknown
timestamp: January 13, 2024, 10:24:55 am
content: Quote from: bdunham7 on January 12, 2024, 11:35:41 pmHow do you know they re-spun the design?

author: bdunham7
author_rank: Super Contributor
timestamp: January 13, 2024, 12:01:26 pm
content: Quote from: EEVblog on January 13, 2024, 10:24:55 amWhen I sent mine in for a battery draw issue thinking it would be the supercap, they informed me that the problem was actually one of the chips on board. They didn't say which one, but the tech did say that particular part was completely NLA and the only fix was to replace the meter. The new meter runs different firmware and the versions are not compatible between the original and new meters. Others have reported that they now use a soldered-in coin cell for the RTC but I haven't seen for myself. Also, I'm pretty sure the boot time is faster.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 13, 2024, 10:19:46 pm
content: Quote from: bdunham7 on January 12, 2024, 11:35:41 pmIf they have made any significant modification of the architecture, I'd somehow highly doubt that would yield anything less bloated - I would actually expect more bloat as time goes by.But the most likely is that they haven't changed much, at least regarding the part I was talking about. What bunch of "obsolete chips" have you identified?

author: floobydust
author_rank: Super Contributor
timestamp: January 13, 2024, 10:42:06 pm
content: From Dave's pics:Fluke28x REV 015U26 - MC9328MXSCVP10, i.MX ARM920T, 100MHz, LCD controller, 2 32-bit timers (oh so many lol), RTC, USB etc. MAPBGA-225 discontinued 01-2021.U28 - 640P30TF65 64Mb as 4MBx16 NOR FLASH BGA-64U25, U27 - IS66WVC2M16ALL, PSRAM 32Mb as 2MBx16, 70ns VFBGA-54 DRAMIt does look like overkill ARM9 even if the LCD is super high res - ultimately the multimeter is reading only one or two quantities, what would a Cray do with all that?I think the added costs - 8 layer board, BGA mix with all that the through-hole, big CPU and memory might have caused the product to be expensive?I got burned once in a product design using that "mobile/cellphone" PSRAM as it has a very low power self-refresh mode - but they all got obsoleted by Micron and the Fluke shows an Intel part and we all know how their venture into mobile went...The memory IC going obsolete, it scuttled my whole project. I would guess that necessitated Fluke board rev. but not sure what they went with or if power drain increased. Assuming the supercap only holds the RTC, not data logs.Quote from: EEVblog on January 12, 2024, 10:19:54 pmIt's single point, high contact pressure and seems to be finicky about production tolerances. Not sure what the outcome was in this threadBM786 Switch Issue.

author: bdunham7
author_rank: Super Contributor
timestamp: January 13, 2024, 11:38:00 pm
content: Quote from: SiliconWizard on January 13, 2024, 10:19:46 pmSince they kept the same model and presumably the same functionality, I wouldn't expect them to make any significant changes, just enough to accomodate parts. I didn't look up everything but for example the cell-phone SRAM chips show obsolete if I looked them up correctly--no surprise there.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 14, 2024, 12:11:44 am
content: I haevn't looked up the exact parts, but PSRAM is relatively easy to source and replacing them is no problem. I bet they could even find the same pinout, as it's probably standard JEDEC stuff?

author: Black Phoenix
author_rank: Super Contributor
timestamp: January 14, 2024, 04:14:14 am
content: Well I've done an experience with my 289. I've been having it with Panasonic Eneloops on it. The charge is the same as it was last time I use it, so no consumption of battery as when it was sent to support where a pack of 6 batteries would be empty in less than a month.But simulating a battery change, so removing the back cover, remove batteries and insert again gave me the message of needing to correct time and date.So I would say that my fix was just the removal of the supercap from the PCB and was left that way.Again I can't be sure because I didn't open the multimeter after repair and I can't be bothered to do it since it works well and the time and date is an easy fix of connecting to the pc and getting the correct time and date via the Fluke ViewForms sync function.It doesn't affect saved data in the memory, only the RTC function.

author: floobydust
author_rank: Super Contributor
timestamp: January 14, 2024, 06:54:42 pm
content: Cellular RAM is constantly obsoleted with no equivalent. It's either VCC or pinout/package as deal breakers, industrial temp range is also much harder to source. It makes designing an embedded system (expanded bus) high risk as you are tied to a part that 1 or 2 manufacturers make with a lifetime of a few years.The IS66WVC2M16ALL PSRAM in standby at <0.15mA will auto-refresh.I'll bet there is an operating system stashed somewhere in meter's firmware, that's why the main CPU is ARM9.

author: bilaal.yousuf
author_rank: Newbie
timestamp: January 15, 2024, 07:38:16 am
content: Does anyone have the schematic for fluke 287 and also for 179 please?

author: EEVblog
author_rank: Unknown
timestamp: January 15, 2024, 08:47:10 am
content: Quote from: bilaal.yousuf on January 15, 2024, 07:38:16 amhttps://www.eevblog.com/forum/testgear/fluke-189iian-(289)-service-manual/?action=dlattach;attach=1964316