Electronics > Repair
Fluke 289 not quite sorted.
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nixxon:
In order to troubleshoot the 289 LCD that is not working, I am thinking about using my fully working 287's parts for troubleshooting.

I want to figure out if the LCD of the non working 289 is all right.

What is the best way to go:

1) Connecting the working 287's LCD to the non working 289 multimeter? or
2) Connecting the non working 289's LCD display to the working 287 multimeter?
ElecSeb:
Expected non-working LCD to Working DMM.
This way when it works you know for sure the LCD works.

Other way around when good LCD attached to defect DMM, you know screen from new unit is good, but if it does not work, you know the Mainboard of the defect DMM is broken. But till that moment you still do not know if the suspected LCD is broken.

My 2 cents
nixxon:

--- Quote from: ElecSeb on October 21, 2018, 07:12:07 am ---Expected non-working LCD to Working DMM.
This way when it works you know for sure the LCD works.

Other way around when good LCD attached to defect DMM, you know screen from new unit is good, but if it does not work, you know the Mainboard of the defect DMM is broken. But till that moment you still do not know if the suspected LCD is broken.

My 2 cents

--- End quote ---

I did as you suggested. The LCD from the 289 woke up fine when connected to my good DMM (287).

It seems that the LCD driver circuit on the 289 is no good. I noticed that one of the crystals had a low amplitude (200 mVpp) the way I measured it. According to the Fluke 27 Service Manual a similar 32.768 kHz crystal should measure 600 mVpp or more.:


* 4. Connect either an oscilloscope or frequency counter, using a low-capacitance probe,
to pin 54 of U1 or to the junction of C17 and Y1 (the crystal). A 32.768 kHz sine
wave with an amplitude of approximately 600 mV peak-to-peak should be present at
the junction of C17 and Y1 (3 V peak-to-peak at U1 pin 54). Note that U2 and the
display will not operate if the clock signal is not present. If the clock signal is not
present, the most likely causes are U1, Y1 or C17.
*
Can a missing (or low) clock signal be a part of the LCD problem when the rest of the meter seems to be working ok?
ElecSeb:
At this moment I do not have a scope available (bought a new one recently and is still in transit).
However did you measure your power lines?

And how do you know that the unit powers-on (sorry if I missed it in your posts).
nixxon:

--- Quote from: ElecSeb on October 21, 2018, 04:37:11 pm ---At this moment I do not have a scope available (bought a new one recently and is still in transit).
However did you measure your power lines?

And how do you know that the unit powers-on (sorry if I missed it in your posts).

--- End quote ---

Hello. Good luck with your new scope. Are you planning to use it to do measurements on a working 287/289?

I have not measured power lines. I  bought the 289 as non working.

I have fixed one fault in the current terminal sensing and updated the firmware from v1.10 to v1.16.

I can read the 289's "screen" via the IR189USB interface on my computer using FlukeView Forms.

Now I am trying to fix it's LCD driving circuit (LCD itself is working) and the resistance measurement function not reaching "OL" while probes are open circuit.
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