Fluke 289 clock drift - Page 1
Forum section: electronics / testgear

author: erazor
author_rank: Newbie
timestamp: July 17, 2014, 03:30:36 pm
content: Hello,I have a new Fluke 289 here and the clock of the device drifts imho extraordinary. The clock looses roughly 1 second in 12 hours, additionally switching off/on seems to costs another 1/3 second. Fluke hotline says it's no realtime clock, that's also why time is not stated in the instructions. Point.My question is: Do other users have the same huge timedrifts or is just my device a standalone-logging-gherkin?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 17, 2014, 04:18:13 pm
content: Possible capacitor problem?Gory details athttps://www.eevblog.com/forum/testgear/fluke-189-with-leaking-surface-mount-coin-cell/

author: LaurenceW
author_rank: Frequent Contributor
timestamp: July 17, 2014, 05:17:46 pm
content: My 289 drifts, similarly. It also "forgets" the time each time (and that is depressingly frequently) I change the batteries. little onboard battery *looks* OK to me, and I'm not about to replace it. But even if this was stuffed, I'd expect the onboard clock to either run or not run, and not simply run a bit slow. Fluke probably don't issue specs on the accuracy of their onboard clock - maybe now we know why.TBH, I've been a bit dissapointed in my '289. It EATS batteries for fun, takes an AGE (well, 8 seconds SEEMS like an age when you want a volt reading NOW) to boot, the and display contrast is poor. Because of the battery consumption (it even draws a small amount of power when switched off), many users including me have the auto-timeout set quite agreesively. Which meansanother8 seconds wait to take a further reading... OK, it does all the other things the manual says it should, but these things just spoil the "user experience" and seem like design fails to me.

author: retiredcaps
author_rank: Super Contributor
timestamp: July 17, 2014, 05:22:55 pm
content: Quote from: LaurenceW on July 17, 2014, 05:17:46 pmSlightly OT, Have you tried Eneloops in the 289?

author: LaurenceW
author_rank: Frequent Contributor
timestamp: July 17, 2014, 08:36:08 pm
content: I absolutely have, Retiredcaps! The problem is twofold - Eneloops have a low self discharge, which makes them last longer if not used, BUT the firkin' Fluke continues to drain the cells (at 120uA) even when off. And with rechargeables running at about 1.1-1.2V, as far as 289 meter hardware is concerned, those are nearly flat, so the meter shuts down! So the eneloops don't last that long even when the meter is on. Loose-loose

author: LaurenceW
author_rank: Frequent Contributor
timestamp: July 17, 2014, 08:51:06 pm
content: CORRECTIONOnce it has settled (and maybe the internal battery is recharged), the off-current is nearer 50uA. That's about 1mAhr drain per day...?

author: casinada
author_rank: Frequent Contributor
timestamp: July 17, 2014, 10:31:43 pm
content: If you take the batteries out and lose the RTC settings it is definitely a supercap problem and Fluke will take care of it. Mine was eating battery before it was repaired and it lost RTC settings each time I changed the batteries. Once it was repaired the battery seems to be holding really well and no more problems with RTC.

author: erazor
author_rank: Newbie
timestamp: July 19, 2014, 08:44:12 am
content: My final thoughts on this:It might be that the device, once recording is running, uses the more reliable mcu clock as source. I haven't tested that, but the return value of a double precision floating point with fractions suggests that. Setting the system time before starting a recording that needs syncronizing with other sources is a inconvenience I could have lived with.The issue with the leaking capacitor is a definitive no-go, thinking about returning the device once in a while (which costs money) for repair and how much more batteries I have to pay in the long run,just because the manufacturer has no permanent fix for this.I returned the 289. Maybe I have a look at the Agilent U1272A.Thanks

author: Brx
author_rank: Newbie
timestamp: March 27, 2018, 07:28:06 pm
content: I found this thread while looking for experiences & info - and maybe some fix/adjust/tweak advice for the clock accuracy on the Fluke 287 and Fluke 289 meters. We've been using four meters at times to do datalogging (yes, I know a dedicated datalogger might sometimes be more prudent, but separate meters is also very flexible for other applications), but regarding the Fluke meters' clock, I noticed that I had set all four meters clocks within a second of each other a little over a week prior, and prior to another logging session, I noticed they were all out of sync, one by more than 20 seconds!I thought that sounds like some very sad clock freq stability...especially considering the room temp is also controlled within 2degC.I went ahead and sync'd the clocks again and started a logging session with all four meters (same current F/W version too BTW) and was able to press all four start buttons in good sync such that I could see the green button blink lights were nearly in perfect sync between meters. Then, about 30min into the recording session, I noticed the green blinks had gotten very noticeably out of sync. 'Not cool' thought, that's seems to be some very poor clock frequency tolerance!Has anyone looked into their meter(s) in attempt to check the clock frequency accuracy?