Lower voltage for resistance measurement for FLuke 289

[TimFox]

If you connect your Fluke to a resistor, does it read correctly?
Is that why they call it an ohmmeter?
If not, it may be busted.

[tonycstech]

So you are telling me that using two probes to measure resistance is not a correct way to do it ?
its a 1.8v rail. Measuring it with 2v or even 5v at the probes will likely cause measurement issues so is there a way to lower the voltage in the firmware of the meter  maybe ?

[bdunham7]

So if i cannot trust FLUKE for giving me expected reading while chinese junk does, i have no point to continue with this conversation because solutions are rather absurd.

The solution would be to understand the circuit in question and for that to happen you'd have to tell us exactly what circuit or DUT you are measuring.  Your low-cost meters typically have lower test currents for the resistance ranges and if you have a circuit that is not ohmic, then you will likely see different results.  This is why I suggested manually using a higher range on the Fluke as this will reduce the test current.  For example, what do you get on this particular measurement if you manually select the 500k range?  That's a 1µA test current.

As far as giving you the "expected" reading, you can be pretty sure that the Fluke is giving you the correct reading, notwithstanding what a bevy of other cheap meters may say.  Why that correct reading doesn't match your expectations or other meters is another story, one I'd encourage you to try to understand.  You can rant and rave all you want and you won't change anyone's mind.

[bdunham7]

So you are telling me that using two probes to measure resistance is not a correct way to do it ?
its a 1.8v rail. Measuring it with 2v or even 5v at the probes will likely cause measurement issues so is there a way to lower the voltage in the firmware of the meter  maybe ?

No, we're telling you that it isn't a resistor.  When you say you are measuring a 1.8V rail, do you mean that you are measuring the part of the circuit that would be powered by a buck regulator with the regulator removed (or not)? 

I previously explained how to lower the maximum applied voltage to about 0.5V if you think that's the issue.  A 50k resistor (47k is close enough) is all you need.  You need to understand that the maximum (open circuit) voltage is only near 5V when the test leads are completely open.  As soon as you have anything connected, the voltage drops.  For the 500R to 500k ranges, if the resistance is within the selected range then the applied voltage will be less than 0.5V.  However, the circuit you are testing is still not a resistor.  Keeping the voltage below 0.5 may cause it to behave ohmically--or not.

[tonycstech]

yes its a buck converter circuit. nothing is removed.
Removal of the buck converter is not an option. I need to know the circuit resistance before i do anything to it.
Measuring at the coil.
So if fluke gives me low ohm reading, it means there is a problem with the circuit.
Meanwhile chinese piece trash says circuit is not low and the device is working normally after all.

So yeah: "just use chinese junk" is the only option i have at this point and all the FLUKE hype is a joke UNLESS you work in some industrial setting.
Otherwise its useless for modern electronics with multi phase controllers and processing units.
Maybe some tractor wiring or construction site measurements its best for FLUKE use but i dont see any use for it in my case. Maybe not this model.

[bdunham7]

Otherwise its useless for modern electronics with multi phase controllers and processing units.
Maybe some tractor wiring or construction site measurements its best for FLUKE use but i dont see any use for it in my case. Maybe not this model.

I assure you people are using Fluke 289s on things other than tractors and construction.  Have you tried or are you willing to try any of the things I've suggested?

[J-R]

https://youtu.be/YXeJ-BQnJtw?t=46

[tonycstech]

https://youtu.be/YXeJ-BQnJtw?t=46

Yep, there is a live demo for ya

[J-R]

https://youtu.be/YXeJ-BQnJtw?t=46

Yep, there is a live demo for ya

I guess there is no other way to say this, but even though you have mad repair skills, you probably need to hit the electronics books a bit...

[tonycstech]

https://youtu.be/YXeJ-BQnJtw?t=46

Yep, there is a live demo for ya

I guess there is no other way to say this, but even though you have mad repair skills, you probably need to hit the electronics books a bit...

All i need to know is if there is any way to hack the device internals so it would obey my will. I think firmware driven device can be hacked by altering the firmware.

[J-R]

https://youtu.be/YXeJ-BQnJtw?t=46

Yep, there is a live demo for ya

I guess there is no other way to say this, but even though you have mad repair skills, you probably need to hit the electronics books a bit...

All i need to know is if there is any way to hack the device internals so it would obey my will. I think firmware driven device can be hacked by altering the firmware.

Oh, but adding a resistor to your test probe was too much to ask for?  Come on now, you've run this train off the tracks...

[bdunham7]

All i need to know is if there is any way to hack the device internals so it would obey my will. I think firmware driven device can be hacked by altering the firmware.

FWIW, in your video when you are showing the "wrong" reading of 218 ohms, the applied voltage is about 210mV so too much voltage isn't really the issue.  Clearly this circuit is non-ohmic and is reacting to the different test currents being applied.  You were correct when you said "I really don't understand how this meter works".  Even If you could modify the firmware, what would you program it to do?

https://youtu.be/YXeJ-BQnJtw?t=46

Even though you may be good at what you are doing, you also clearly have no idea exactly what it is that you are doing and no inclination to learn.  You never responded to my suggestions even though your video shows you already tried some of them.  Why waste our time?