Fluke 289 power button light - Page 1
Forum section: electronics / testgear

author: Dubbie
author_rank: Unknown
timestamp: July 02, 2018, 09:03:46 pm
content: Is it just mine, or is it normal for the Fluke 289 to have it's power button LED lit permanently, even when it is off?It's not very bright, but it's still probably sucking a mA or two.No wonder the batteries drain on the stupid thing.I can't find anything on google about this, so I thought I would ask here.

author: Daruosha
author_rank: Regular Contributor
timestamp: July 02, 2018, 09:12:16 pm
content: I have two Fluke 289s and none of them has permanently lit power button LED.

author: Dubbie
author_rank: Unknown
timestamp: July 02, 2018, 09:21:39 pm
content: And the mystery deepens...I took the back off again to measure the "off" current draw. It measures ~0.39mA which seems ok I guess...BUT the light has now gone off! It turns on as usual when the meter is turned on, but when it is off it is off.So I guess whatever was causing the button to stay lit isn't doing it anymore. (It was doing it as well before I last changed the batteries.)BTW, the current draw when the meter is on and measuring is ~21mA which seems reasonable. None of those values explain why my meter uses a set of batteries about once every 3 months. The only thing I can think is maybe the thing was actually still on and drawing a few mA the whole time.

author: tautech
author_rank: Super Contributor
timestamp: July 02, 2018, 09:35:17 pm
content: Dubbie, could the LED just be illuminated when it's gone into sleep mode ?Do they have that ?

author: iainwhite
author_rank: Unknown
timestamp: July 02, 2018, 09:43:30 pm
content: Another thought - was it perhaps in logging mode when the led was staying on?

author: retiredcaps
author_rank: Super Contributor
timestamp: July 02, 2018, 09:56:11 pm
content: Maybe you have a bad supercap? Seehttps://www.eevblog.com/forum/testgear/fluke-189-with-leaking-surface-mount-coin-cell/?all

author: Dubbie
author_rank: Unknown
timestamp: July 02, 2018, 10:47:00 pm
content: My coin cell was corroding. Have removed and will replace.It has zero charge left. Not even a flicker.No sign of any leakage damage on the board. It looks immaculate.Hopefully the dead cell was the reason for the wonky behavior.

author: Dubbie
author_rank: Unknown
timestamp: July 03, 2018, 05:05:45 am
content: So I put it back together with the supercap removed.The stupid powerbutton light is on again all the time!It's not as bright as before, but it is on.The video below shows the meter starting off, I press the button to turn it on, wait for it to start, then turn it off again. You can see the starting and ending state is quite dim compared to turning on, but it IS on.https://youtu.be/PnZ_8_ZNqJI

author: retiredcaps
author_rank: Super Contributor
timestamp: July 03, 2018, 06:00:24 am
content: Quote from: Dubbie on July 02, 2018, 10:47:00 pmWhat about the other side of the pcb where S5/DS4 is as perhttps://www.eevblog.com/forum/reviews/fluke-287-dmm-teardown-and-photos/?action=dlattach;attach=11258;imagefromhttps://www.eevblog.com/forum/reviews/fluke-287-dmm-teardown-and-photos/

author: Dubbie
author_rank: Unknown
timestamp: July 06, 2018, 12:26:32 pm
content: Just to conclude this thread, I replaced the super cap. I inspected both sides of the board. Both sides are immaculate. The power button still glows when it is off. I dunno. I give up!

author: Terry01
author_rank: Frequent Contributor
timestamp: July 06, 2018, 02:09:08 pm
content: I think mine is ok???

author: retiredcaps
author_rank: Super Contributor
timestamp: July 06, 2018, 08:03:41 pm
content: Quote from: Dubbie on July 06, 2018, 12:26:32 pmI don't have this meter, but final suggestions which may or may not make sense are1) reset back to factory defaults2) check firmware to see if you have the latest - if not consider upgrading?

author: Dubbie
author_rank: Unknown
timestamp: July 06, 2018, 08:48:32 pm
content: Quote from: retiredcaps on July 06, 2018, 08:03:41 pmHave done both these things.

author: Terry01
author_rank: Frequent Contributor
timestamp: July 07, 2018, 10:24:56 am
content: Quote from: Terry01 on July 06, 2018, 02:09:08 pmDoes any1 else think my cap looks upside down compared to others or am I just tripping?

author: Gregg
author_rank: Super Contributor
timestamp: July 07, 2018, 05:37:37 pm
content: Does any1 else think my cap looks upside down compared to others or am I just tripping?Maybe you have the new model with a coin cell instead of the super cap. It does look like the polarity of a coin cell.

author: james_s
author_rank: Super Contributor
timestamp: July 07, 2018, 06:25:19 pm
content: Can you tell what drives the LED? Maybe a pullup or pulldown resistor has failed or a transistor/mosfet is leaky? It doesn't take much current to make an LED glow.

author: Dubbie
author_rank: Unknown
timestamp: July 07, 2018, 11:08:51 pm
content: Thing is, it does turn off properly when the meter is on. I presume it is just hanging off a microcontroller gpio although I could be wrong. I don’t really have the time to trace it out and figure out what is happening, so I guess I’ll just live with it.

author: Terry01
author_rank: Frequent Contributor
timestamp: July 08, 2018, 01:07:12 pm
content: Quote from: Gregg on July 07, 2018, 05:37:37 pmMaybe you have the new model with a coin cell instead of the super cap. It does look like the polarity of a coin cell.Ah, cool! Thanks for the reply and I agree it does look like a coin cell too. I hope it is anyways

author: Terry01
author_rank: Frequent Contributor
timestamp: July 08, 2018, 01:10:08 pm
content: Quote from: Dubbie on July 07, 2018, 11:08:51 pmMaybe try just taking the battery compartment off and then back on again and see if it goes away again. You might be lucky. It sounds like something just moving a fraction or something when you move the battery compartment.One of those proper PITA problems!

author: nixxon
author_rank: Frequent Contributor
timestamp: October 02, 2020, 11:08:16 pm
content: Quote from: Terry01 on July 07, 2018, 10:24:56 amOh no! All the electons have probably fallen out by now. Did you contact Fluke about the missing electrons and the oddly lit LED?

author: coppercone2
author_rank: Super Contributor
timestamp: October 03, 2020, 09:40:56 pm
content: yikes, I was hoping the off current draw was something like 5uA. I know it has a RTC, I never measured mine.I think other people reported a reasonable off current draw for a new meter is something like 50uA. I think you have a fault in the soft switch. Maybe the impedance is not well defined. I think more then a few hundred uA and you have a instrument thats going to leak batteries if you forget about it.You draw gives you <1 year. If it draws 50uA you get 4.5 years

author: Dubbie
author_rank: Unknown
timestamp: October 06, 2020, 10:07:58 pm
content: Old thread, but I ended up solving this one.Traced the power LED to this mosfet...

author: BravoV
author_rank: Super Contributor
timestamp: October 07, 2020, 08:28:18 am
content: Quote from: Dubbie on October 06, 2020, 10:07:58 pmHey Dubbie, what happened to that mosfet ? Busted open drain-source ?Also did you identify part no. for that mosfet ?

author: Dubbie
author_rank: Unknown
timestamp: October 07, 2020, 09:54:56 am
content: Look carefully at the center of the image..There was no need to replace any parts.