Solved:Fluke 189 multimeter - functions button not working after wrong measuring

[techboy]

Hello guys,
New here, have not realised how electronic centred EEVblog can be. Glad I found it.

I had an issue with my Fluke 189, where accidentally measured low voltage 5-12V while I was on Diode mode. I am glad my Fluke survived and is working fine, although the blue circle button (refer to the picture) to switch to functions like Diode or Continuity mode stop functioning. As the current knob position is right now, I cannot switch the multimeter to continuity mode.



I took it apart and reset the memory by resoldering the battery but still not functioning. Run quick measuring on the board but resistors and transistors seem to be fine. No burn marks as it was low voltage.
All other functions of the multimeter seem to be fine. Fuses are all fine.

Does anyone have experience with repairing multimeters? I spoke with Fluke authorised service, but this model is discontinued and no parts available, unfortunately. They quoted me almost $200 bench fee with no clear results. Considering they cannot get parts, my chances are they probably cannot get replacement board either.

I can take higher resolution photos of the PCB if it's going to help? Although these ones from @bdallen87's post on this forum are quite accurate




I cannot find any schematic of it unfortunately. Only Fluke schematic I manage to scrape was Fluke 17B

Regards

[goaty]

Maby _just_ the blue button stopped working ? Tried cleaning the PCB and the Button contact surface ?

[techboy]

@Goaty you are a star.

How I did not tough of that. And in our engineering course we were taught to start troubleshooting by the simplest link. It must be just a coincidence that it failed at that exact moment.

I cleaned the pads before but haven't tough of the button itself. When you think about it this is one of the most used buttons on this multimeter.

[goaty]

I hope I´ll remember to check that first once my 189 dies ;-)
Great it is ok again.

[shakalnokturn]

While you're in there maybe evaluate the condition of the backup capacitor before it brings you extra problems. (Other than losing saved measurements...)

[JFJ]

I had an issue with my Fluke 189, where accidentally measured low voltage 5-12V while I was on Diode mode.,  I am glad my Fluke survived and is working fine...

Even applying mains voltage in diode mode shouldn't cause any damage to a Fluke multimeter. As an example, please see Dave's overload test - at 12 minutes and 20 seconds into this review:

[BigB_52]

Hi,
I have a Fluke 189 which was in storage for a long time with batteries in, when I took it out the battery was corroded, I cleaned the battery cartridge, placed new batteries and turned it on the meter was running for itself without measuring anything, probs were in the air and no matter where the selector switch was. I opened the meter to inspect inside found nothing wrong, no battery liquid leaked and it was supper clean, I changed the supper cap, nothing changed in the result, I sent it for calibration they reported “the meter can not register calibration constants.
I tested the eprom 93c56 that holds the calibration constants, it is fine,I can read from and write to it with no problem with an external eprom programmer.
Since it came back from calibration facility, the UNCAL mark is on the screen All the time, and the mere shows 0000 in all conditions, even when I activate calibration mode the measurement is zero, the measurement does not follow the input to match the required voltage calibration menu,
Any one has any thought in that?

Thanks
Ben

[shakalnokturn]

A note on the 93C56 although I don't think your problem is there: I think some models are 3V to 5V Vcc parts (would need to check datasheet) in the 189 Vcc should be in the 3-3.3V range (worth checking) , verifying it on an universal programmer it may have a different supply voltage.

Having a strange behaviour and not showing any input reading at all sounds bad. You could at least check the input is reaching whatever ASIC to start with.

The Fluke 89-IV service manual is around, that should give you a good starting point if you want to troubleshoot properly.

[coromonadalix]

The Fluke 89-IV service manual   has no schematics in it