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Fluke 189 with leaking surface mount supercap (also Fluke 287, Fluke 289)

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BravoV:

--- Quote from: ron on January 10, 2014, 06:44:26 pm ---What corrosion?  What "corrosive" material is in a cap?  Remember that the original poster thought it was a battery cell.

I just checked my oldest 189 and sure enough the cap had obviously leaked.  I used a tooth pick to remove the most of the dried brown crud (Latin term for dielectric?) and wiped the remaining residue off with a q-tip dampened with IPA.  Looks clean now.  Under a 20x loupe, I see no pitting or "corrosion" on the cap case.   The residue is harmless except it indicates a failed or failing cap.
Yes, this cap has a problem, but it isn't going to corrode the pcb or anything else.
Don't panic.  :)

--- End quote ---

If cap already oozed out so many of it's internal material, let alone this goo if its harmless, but then this raised few questions :

* Does the leakage current still at < 150uA as new one ?
* If the internal leakage is increasing, then how much ? Will the cap suck the battery charge significantly even the DMM is at OFF position, since its basically connected all the time to the battery.Still don't have time to measure my 287s off current.  :'(

ron:

--- Quote from: BravoV on January 11, 2014, 11:31:22 am ---
If cap already oozed out so many of it's internal material, let alone this goo if its harmless, but then this raised few questions :

* Does the leakage current still at < 150uA as new one ?
* If the internal leakage is increasing, then how much ? Will the cap suck the battery charge significantly even the DMM is at OFF position, since its basically connected all the time to the battery.Still don't have time to measure my 287s off current.  :'(

--- End quote ---


The cap apparently failed open(or nearly open), as would be expected.  Current draw in off position is <70uA.  This meter does forget time when batteries are removed -- a non issue for me. 
I checked another 189 and 2 289's and they are OK.  Using enerloops, battery life in all of my X89 meters is much better than spec.

SoundTech-LG:
Hi,

I'll have to tear into it and check, but I bought a 189 off ebay recently. When it arrived it was dead. Replaced the batteries, and it came right up.
Curious now if the supercap is the reason.

SoundTech-LG:
Had the creeping crud...   removed the cap entirely. Cleaned up the mess on the board. Not sure I will be installing a replacement. Never use logging storage. Oh, date/time...  maybe I will replace!

true:

--- Quote from: BravoV on January 07, 2014, 07:16:27 am ---
--- Quote from: Huluvu on January 07, 2014, 07:06:29 am ---
--- Quote from: mjlorton on January 07, 2014, 12:43:02 am ---> The good news is the supercap is only in the unit to maintain the units date and time. It has no other purpose. It does not support instrument memory or logged /saved readings.

--- End quote ---

What about removing the supercap permanently from the Meter?
I rarely use the logging capability.

--- End quote ---

Or maybe replace it with just ordinary lower capacitance cap, but good and reliable one ?

--- End quote ---

I wrote this earlier in the thread, but I did just this and it works fine.

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