SIGMA SG888L Multimeter Repair
I was working on some repair & noticed my Multimeter is not showing one line in first digit segment. So I kept the repair work a side to first tackle this fault.
I found very rarely display or circuit problem, 95% this problem is arriving because of poor contact between display & PCB.
So I opened the Multimeter for further process. Removed back cover & removed four screws from the circuit.
It looks clean but when cleaned using IPA on cloth & cleaned the surface of the contacts…
Cleaned the contacts with IPA then rubbed eraser on contacts to cleaned it properly.
Also removed rubber which is having conductive traces on it, though it passes signal from PCB to display. That is also cleaned using IPA on cotton bud.
After cleaning process, I reassembled everything back & connected the battery to it to see the result.
Now, meter is in good working condition and fault is solved.
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles on Sandwich Toaster Repaired
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Waleed Rishmawi
August 3, 2024 at 9:30 pm
Great work. Have a blessed day
Yogesh Panchal
August 3, 2024 at 11:19 pm
Thank you!Waleed
Tayo
August 3, 2024 at 10:31 pm
Good one. What product would you apply to prevent future corrosion?
Yogesh Panchal
August 4, 2024 at 11:30 pm
Thank you! Toyo,
i just cleaned it with IPA, not familiar with the product which stop future corrosion & same time allow proper electric conductivity.
Andy Shiekh
August 3, 2024 at 10:48 pm
I tend to put silicone oil on the contacts to avoid subsequent oxidation.
Yogesh Panchal
August 4, 2024 at 11:38 pm
Andy Shiekh,
thanks for your input,Silicone oil is dielectric works good as insulator grease & Lubricating but doubtful that it will prevent further oxidation with good Electric conductivity.
Parasuraman S
August 3, 2024 at 10:58 pm
Great work to fix our own tools! Many thanks for sharing a very detailed article on fixing the multimeter!
Yogesh Panchal
August 5, 2024 at 12:04 am
It will disturbing when your always supporting tool breakdown.
Thanks!
Albert van Bemmelen
August 3, 2024 at 11:34 pm
Devices with lcd screens with conductive rubber strips are prefered over those that are connected with fragile flexprints that are very hard to repair when broken. The rubber contact strips also can be found in older lcd watches.
Yogesh Panchal
August 5, 2024 at 12:12 am
You are Right Albert,after so many years invented LCD still no other options.
Mark J
August 4, 2024 at 2:33 am
Yogesh Panchal Good job on the repair.
Yogesh Panchal
August 5, 2024 at 12:12 am
Thanks! Mark j
Imoudu.O
August 5, 2024 at 2:45 am
I 've done this type of repair also on my dmm, however i have such problem on my microwave oven, i don't know how to go about it.Does anyone has an idea.
Yogesh Panchal
August 6, 2024 at 10:41 pm
Not clear,What problem you are facing?
Lee
August 6, 2024 at 8:11 pm
Imoudu.O
If its a vfd (vacuum fluorescent display) try looking for an e-cap on the vfd board and change it.
I learnt this from my old boss back when he was repairing VCR's 20 od years ago.