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Electronics => Repair => Topic started by: regged on April 17, 2021, 06:14:35 pm

Title: Fluke 289 do not measure resistance
Post by: regged on April 17, 2021, 06:14:35 pm
Hi all. Is there any schematics to understand how resistance measure works? Everything works except ohms, lo 50ohm also work. But when i choose ohms, DMM shows 150Kom all time. When i short leads, it shows 2.3 Ohms.
Title: Re: Fluke 289 do not measure resistance
Post by: retiredcaps on April 17, 2021, 07:00:00 pm
I suggest checking all the input protection like the PTC, MOVs, fusible resistor, etc.  The PTC should be around 1K ohm, the MOV's should be open circuit and fusible resistor around 1K ohm.

Also, if your 289 had battery leakage, it would be a good idea to clean the entire PCB with 99% IPA.
Title: Re: Fluke 289 do not measure resistance
Post by: Grandchuck on April 17, 2021, 07:01:47 pm
Also, there might be a pair of transistors serving as a voltage clamp (Zener) which could be damaged.
Title: Re: Fluke 289 do not measure resistance
Post by: Trader on April 17, 2021, 09:52:12 pm
A Fluke 289 has a lifetime warranty, did you check this?
Title: Re: Fluke 289 do not measure resistance
Post by: regged on April 18, 2021, 06:57:55 am
Can you show which thermistors and varistors? I found one green ptc with R112 marking. This probably exploded.
Title: Re: Fluke 289 do not measure resistance
Post by: regged on April 18, 2021, 12:38:15 pm
I checked between com and V leads, there is ~150Kom and this resistance always shows on display.
Title: Re: Fluke 289 do not measure resistance
Post by: retiredcaps on April 18, 2021, 06:33:57 pm
Quote from: regged on April 18, 2021, 06:57:55 am
Can you show which thermistors and varistors? I found one green ptc with R112 marking. This probably exploded.
Post clear focused pictures of the PCB so we can see what you are talking about.
Title: Re: Fluke 289 do not measure resistance
Post by: BeBuLamar on April 22, 2021, 08:26:32 pm
Why don't you simply send it back to Fluke for repair. It should be free.
Title: Re: Fluke 289 do not measure resistance
Post by: Elliotsk on April 24, 2021, 01:15:15 am
I had the same problem ALSO the audible continuity worked intermittently as well.  HERE is the fix that worked perfectly.  For some reason the test leads on new Flukes have had some kind of coating on the outside that screws up the resistance and continuity tests.  Take a small patch of scotch-brite or very very fine sandpaper and clean the probe tips tip to base.   BAM! Problems solved for me!  Fingers crossed for you!