Electronics > Repair
Please help, FLUKE 8920A Multimeter Repair
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daisizhou:

--- Quote from: Harry_22 on June 13, 2024, 08:27:35 pm ---Ok, make an ajustment according paragraph 4-48 on page 4-19 steps from 1 to 8.
Adjust only R72 according step 5  and R26 - step 8.

--- End quote ---

**I haven't made any adjustments yet,I followed the steps to measure,I don't know if my measurements are correct,And whether some of the preparatory steps in the early stage are correct**

It seems that R72 does not need to be adjusted because TP3 is less than 1mv。
R26 may need to be adjusted since TP3 is greater than 1mv(2.3mV-2.2mV)
(TP3 TEST NO2----- I modified AMPLIFIER A, TP3 voltage is about 2.3mV-2.2mV)

Don't P101 and P103 need to be disassembled and thoroughly cleaned?






https://i.postimg.cc/m2DfyqnC/55.jpg
daisizhou:
I need to use the hose again and blow air with my mouth to test the voltage at each test point of P101 and P103 and see if there is any change during the blowing process?
Harry_22:

--- Quote from: daisizhou on June 14, 2024, 12:20:47 pm ---I need to use the hose again and blow air with my mouth to test the voltage at each test point of P101 and P103 and see if there is any change during the blowing process?

--- End quote ---

No, enough is enough.

I will have a look soon.
daisizhou:
I tried to capture this part of the waveform. I don't know if it can help your analysis. Please check it out.


PS:I have a suggestion to disassemble and separate the module motherboard shown in the red box in the figure below.
     Then install and restore 8920A, turn on the power, and press "LOW RANGE ENABLE",
     If the fault disappears, then the fault is on the main board of the red-framed module.
     If the fault persists, then the fault is on the largest bottom plate.
     Do you think it is necessary to make such an attempt?
I tried the above test,Without module mainboard installed, analog pointer keeps deflecting to the right (full scale)

Return to normal state,"LO RANGE ENABLE" swing is always effective in "AUTO" gear,If I press the "HOLD" button and try to jump to 2mv, 200mv, 2v, 20v, 200v, 700v, there is no swing


Harry_22:
First warm it up for about 15 minutes.
Connect the load.
Then switch it to "LO RANGE"  and adjust the zero reading by R26.
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