Multimeter Repaired For Unstable Reading Problem
Meter on my work bench start behaving abnormally, Digits keeps changing on the display.
I thought it is time for new Multimeter because this problem is may be because of the main IC which is not worth to replace.
In spite of doubt I opened the meter for inspection.
On visual inspection component side everything seems ok so removed the PCB from the case for inspecting back side of PCB. While removing the PCB I feel like Mylar Capacitor is bit like dry solder but when I removed the PCB I found one leg of capacitor is loose in the PCB. I desoldered the Capacitor I found Ripped off pad along with its trace.
It is very tiny trace less then 1mm in width & it very difficult to solder. Managed to solder it under Magnifier Glass for this type of soldering you need needle type thin soldering iron tip or chances are very highly to damage nearby traces.
But this doesn’t work because when you solder from other side this wire will easily come out from the solder so for firmly holding I used “UV Solder Mask Ink”. Now a day’s for electronics repair every technicians must have this “Solder Mask” for jumper work in the circuit.
UV LED light is required for curing the ink. UV LED Light is bit expansive but you can make it in few cents. Just buy 5mm UV LED Will work and it will take 1 Minute to set the Solder Mask Ink in to harden epoxy as well it works as insulator.
In solder mask 10ML syringe you can do thousands of masking I used my tweezer tip to apply. You have to apply in thin layer or it will take long time for curing.
Applied UV Light for 1 Minute & ink gets harden.
Re soldered the Mylar Capacitor back to its location.
Now reassembled the Multimeter for testing and result is positive.
Now digits are stable on the screen.
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 ACER Desktop Motherboard Repaired