Author Topic: Fluke 189 strange readings  (Read 1882 times)

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Offline Samogon

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Re: Fluke 189 strange readings
« Reply #25 on: September 03, 2019, 08:22:21 pm »
I believe it is ADC chip, meter is on the waiting for repair shelf, will update when i start working on it.

Yes, please, do let us know of anything else you may find when working on it.

Thanks!

So in my case it was ADC asic, and i have found that any slight contamination causes it erratic readings.

« Last Edit: September 03, 2019, 08:25:38 pm by Samogon »
 

Offline retiredcaps

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Re: Fluke 189 strange readings
« Reply #26 on: September 03, 2019, 10:25:13 pm »
Does anyone know if the buzzer will eventually recover, or I'd better look for a replacement?
Has the buzzer improved?  Maybe it's still not dry with IPA trapped inside?  Maybe direct some air to the hole?

If not improved, you could probably get a replacement from digikey/mouser.  I don't know the part number or specs, but you could probably find the right parameters using a scope?
 

Offline retiredcaps

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Re: Fluke 189 strange readings
« Reply #27 on: September 03, 2019, 10:27:03 pm »
So in my case it was ADC asic, and i have found that any slight contamination causes it erratic readings.

It's not clear to me so can you please clarify if you actually replaced the ADC or just washed it with IPA?
 

Offline Samogon

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Re: Fluke 189 strange readings
« Reply #28 on: September 03, 2019, 11:59:40 pm »
I did replace ASIC. And it fixed one of the problems reading 10 Ohms on short.
I just noticed that any contamination of this greatly affects reading. I made several cleaning steps and every step showed improvement. Lastly i ran it in the Crest ultrasonic cleaner with Branson EC 3% solution.
That brought it to specs operation.
 

Offline giosif

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Re: Fluke 189 strange readings
« Reply #29 on: September 14, 2019, 09:36:30 am »
Has the buzzer improved?  Maybe it's still not dry with IPA trapped inside?  Maybe direct some air to the hole?

If not improved, you could probably get a replacement from digikey/mouser.  I don't know the part number or specs, but you could probably find the right parameters using a scope?
No, it hasn't.
I tried applying heat, blowing air, bumping it on the sides, then on the top and bottom, but there was no change.
I tested again even now, and it is the same.
One thing I did notice, though, was that, if I let the buzzer sound continuously for 1 minute or so, it would start to become louder.
But, then, if I let it sit half a minute or so and sound the buzzer again, it would go back to a fainter sound.

In the end, I just bought a cheap 5V buzzer off eBay - probably an unknown brand, but I don't think that matters for this kind of component.
 

Offline giosif

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Re: Fluke 189 strange readings
« Reply #30 on: September 14, 2019, 09:38:02 am »
I did replace ASIC. And it fixed one of the problems reading 10 Ohms on short.
I just noticed that any contamination of this greatly affects reading. I made several cleaning steps and every step showed improvement. Lastly i ran it in the Crest ultrasonic cleaner with Branson EC 3% solution.
That brought it to specs operation.

And had you tried these same cleaning steps with the original ASIC?
Or that was definitely broken?
 

Offline Samogon

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Re: Fluke 189 strange readings
« Reply #31 on: September 14, 2019, 04:36:48 pm »
Yes both times ultrasonic cleaning.
I was just curious how it would behave before cleaning, it was awful, erroneously reading buzzer going off all the time.
 

Offline giosif

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Re: Fluke 189 strange readings
« Reply #32 on: September 14, 2019, 10:30:10 pm »
Oh, wow.
So, it couldn't have been just contamination for the original ASIC.
I wonder what else it could have happened to it, then: overvoltage?
 

Offline Samogon

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Re: Fluke 189 strange readings
« Reply #33 on: September 15, 2019, 01:18:27 am »
Nope original was bad, replacement did the trick. My point was that this area really sensitive. Which my tests before snd after cleaning proved
 


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