Digital Multimeter Repaired
Some days ago I got unhappy because my Digital Multimeter (DMM) suddenly stopped working. What was the complaint? It did not switch on. I own an Analog Multimeter, but I prefer the DMM.
As you can see it’s a DT9205A, and it was bought from the HUNTER store in my country last year. I talked to a colleague who has a similar (same model) and his DMM had happened the same situation a some time ago, he told me he had exchanged the switch button for the Data hold button.
I said to him: no, I’m going to repair the switch button. So I began to disarm my DMM, 3 screws in the back cover plus one in the battery cover.
Next step was to separate the PCB, only 6 screws.
As I do not have a handy de-soldering tool I used a traditional method in my country to extract the switch from the PCB: the injection needle (look at the photos below). In other words, heating the solder point and push down the needle to separate the tin from the tip of the component
Why did not I use a vacuum de-soldering pump? Because the rails of this area in the PCB were very thin and I was afraid of destroying them.
Look at the result then.
The switch was extracted from the PCB.
It was disarmed into pieces, for clean and lubricates it. Finally it was armed again. Look at the photos below.
All the contacts (fixed and mobile ones) were cleaned with a piece of paper and lubricated with “3 in 1” lubricating oil.
When the switch was re-soldered in the PCB and the device was armed, look at the result when it was switched on.
I tested my DMM in the different scales and for showing some of these tests; I took photos when I was testing the resistors supplied with my Blue ESR Meter: 82 Ω and 5.6 Ohm for alignment.
I could not deny I was very happy now; my own DMM was safe and done now.
This article was prepared for you by Humberto Rodriguez, one of our ‘Master Authors’ from Cuba.
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