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

I tested it, and it seems to have no effect.

It's night here, the light may not be very good.

Do I need to wait for the fault to recur before repeating this test?

By the way, I found that my 8920a host is missing this PCB. Is this normal?

Harry_22:
Seems you have no ground connection of 8920.
Please do the following:
1. Connect metal case to the ground.
2. Connect oscilloscope to TP1
3. Push Low Range button
4. Switch on 8920
5. Check 8.6 volt at TP1
6. Touch C18 by hot soldering iron.
7. Observe oscilloscope
daisizhou:
I took apart the electrical outlet panel from the wall,Found that it only has a "blue" neutral wire and a "red" live wire, and no yellow ground wire.So I don't know about your suggested metal shield case grounding, how should I connect it

Also, as suggested by "blackdog", replace these red tantalum capacitors,Because these tantalum capacitors will fail after long-term use.According to my experience, most tantalum capacitor failures are caused by breakdown and short circuit, and this is the first time I have encountered leakage current.
Do you think I need to replace them all?
Harry_22:
There is a whole topic regarding how to do grounding correctly. All equipment requires grounding. You can use a nearby metal base or pipe.
I do not recommend replacing all capacitors. It is not for nothing that tantalum is used in medical equipment. Change only the critical 1uF in both amplifiers.
daisizhou:
Ok, I'm going to spend some time looking for a real ground test point.

My original plan was to replace tantalum capacitors with 35V or 50V withstand voltage specifications, not electrolytic capacitors.I understand that tantalum capacitors have special functions.Because these red tantalum capacitors have been in operation for 20-30 years,Isn't replacing them in advance the best option?

Do you mean to just replace the C18 35V 1UF tantalum capacitor with a 35V1UF or 50V1UF tantalum capacitor?Other tantalum capacitors remain in their original state
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