Fluke 189 rescue

[Ja-no]

Some time ago I bought a fluke 189 for cheap. Was advertised as non functional but after some troubleshooting I managed to get it working.

On first inspection I noticed that 2 case screws were missing, the battery terminals seemed to have leakage corrosion, the high amp fuse was not the correct one (25A instead of 11) and the 440mA fuse was blown. Despite this I proceeded with the preliminary inspection.

First I decided to address the leakage in the battery terminals. I cleaned them a little with a cotton swab and vinegar to discard battery power issues and begin testing. After cleaning the terminals I put on some batteries and the meter turned on! But alas there were more issues...

When putting the meter in the different functions via the rotary knob the screen showed some segments, but the display then started to fade. I suspected dirty screen contacts or some issue with the LCD power supply. I then decided to take the meter apart.

After dissasembling the case I noticed that one screw post was broken. I checked the board but the meter did not seem to have any visible electrical damage (I even checked the supercap for leakage or shorts, but it was fine). However, two of the screen tabs were broken.

I suspected that was part of the LCD issue, so I cleaned the contacts anyways and taped the tab sections of the screen to the board using electrial tape. I put the meter back together and used the two screws on the top of the case to make sure that it was tight enough for the screen to make contact with the PCB.

Success! after putting the batteries on again the display worked! It displayed all segments and every function appeared correctly on the display. However the switch function button didn't seem to work. I plugged in some leads and started making some measurments...

But no reading was shown on the meter, it appeared as if I weren't measuring anything. Voltage oscillating near 0 when in the voltage ranges, OL when in ohms, open when measuring temperature. However, the amp ranges seemed to detect lacking fuses and incorrect lead placement.

Since everything seemed to work well I suspected lead continuity to the meter, so I opened it again, connected a lead to eack jack input and tested continuity to the pcb traces to which they were connected. The A/mA, uA and V jacks seemed to test ok, but the COM jack tested open. I soldered a wire to the COM trace to make low voltage, resistance and capacitance measurments, and it worked! So I decided to take a closer look at the input jack assembly.

On closer inspection i discovered that it was damaged, and it seemed a repair was attempted using superglue. I researched more on jack assembly issues and stumbled upon MrModemhead's article on Fluke 80 series jack repair (http://mrmodemhead.com/blog/fluke-80-series-jack-assembly-rebuild/), which seemed very similar to the one on the 189.

I decided to desolder the jack assembly and see if the issue was similar to the one on MrModemhead's article (this was one of the most time consuming parts of the project). Both tabs of the COM jack and one of the V jack were broken, as well as the plastic sleeves of both.

I rebuilt both jacks as per the instructions on MrModemhead's site and the meter started showing readings taken with leads connected to its inputs.

I fixed the non working switch function button with some double sided tape and aluminum foil, and I managed to clean the case using only dish soap, water and a brush.

I attached before and after pictures of the meter. In the second picture the meter is measuring a 5v LT1236.

I will add more posts with more pictures and descriptions of the process.

[Ja-no]

A picture of the battery terminals after a preliminary cleaning with vinegar, the wire used to troubleshoot the jack assembly can be seen.


A closer look at how the wire was attached for testing


The broken tabs of the LCD, I have the pieces, but I dont think that gluing them back on would work (perhaps I'm wrong)


Nothing electrical tape can't fix 

[Ja-no]

The damage to the jack assembly. There was superglue on the cracked plastic


The broken tabs are visible when the assembly is desoldered


The brass jack replacements made by following MrModemhead's article


Test fitting the jacks on the assembly


Te assembly sealed with epoxy

[Ja-no]

THe function button fix using tin foil and double sided tape. I first put the tape in the matte side of the foil, exposed the other side of the tape and using scissors and a toothpick cut the taped foil to size, which I then attached to the button (using the same toothpick)



The case before and after cleaning



A more professional screen fix using kapton tape 

[BILLPOD]

Good Morning Ja-no,  Great job on that 189.    I've had mine since
around 2008, and bought it new because of the recording feature.
I can't imagine what your meter was subjected to in order for there to be so much damage, but you apparently got it working again.   Also, great job on your write up and pictures.  There aren't a whole lot of 189s in the wild, so we have to take care of ours.

[retiredcaps]

Excellent repair job.   

Modemhead doesn't visit very often here, but I'll ping him tomorrow to check out this thread.

[Michael YYZ]

I’m amazed. Well done! 

[bc888]

Really, really appreciate the share. Thanks! Good work.

[ModemHead]

Really nice work on the repair!  The 189 is a great meter and totally worth the effort.