How To Use A Multimeter In Mobile Phone Repairs

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Learn how to use a multimeter in mobile phone repairs by reading this guide. A multimeter is used for testing and to check readings of various parts and components in a mobile phone.

There are two types of multimeters available in the market. They are

1. Digital Multimeter
2. Analog Multimeter

You can use any type of the ones mentioned above as both of them will do the same thing. The only difference is that a digital one will show you the readings in digital format thereby saving you time and effort. While in an analog one, you will have to see the reading as per the arrow on its screen. Most technicians prefer to use the digital models. The analog models are used by old generation technicians, as they love and have a distinct affinity to them!

A multimeter whether digital or analog has two wires (also called probes), a red and a black wire. The red probe is positive (+), while the black probe is negative(-). In electronics, always red is positive and black is negative.

When you buy a new multimeter, insert one end of the red probe in VΩ slot (round hole), and the black probe in the COM (means common) slot. The 3rd slot i.e 10A or 20A is not used in cell phone repairs.

In mobile phone repairs, we use only any 1 of the below given settings in multimeter:

1. DC Volt Setting: We use this setting to check the voltages of the things to be checked. In DC volt setting the output voltage of various things like battery, battery connector, charger, charging connector, etc. can be checked. It is indicated by a capital V and straight line with 3 dots below it.

Read how to check voltage of a cell phone battery

2.  Resistance Setting:  By this meter, the resistance of various parts like resistors, etc can be checked. We can also check resistance between 2 points if it is instructed to check in a service manual to check it to get a particular reading while repairing a fault in the motherboard. We can also check the microphone of cell phone with this setting.

Read how to check a resistor in cell phones.

3.  Continuity:  This is also called diode setting. When you touch the red and the black probe ends while on this setting, you will be able to hear a beep sound. By keeping the multimeter on this setting, we can check the continuity between the given 2 points. We can check whether the tracks are open or not. If the multimeter shows continuity, it will give a beep sound. That will mean that the track is ok. And if it does not beep, it will mean that the track is broken. To repair a broken track, all technicians make jumpers. Jumpering means soldering a thin insulated wire from one end of a broken track to the other end.

With this setting, we also check whether the circuit board is short or not. We check the shorting by keeping the wires on the positive and negative terminals of the battery connector and also reverse the wires. If we get beep sound both ways then the circuit board is short, if we get beep sound only once then it is not short.

In some models of cell phones, you will not hear the beep sound. Instead you will either see some reading (like 255, 282, etc) on the screen of the multimeter or just 1. So if you see reading 2 times i.e even after reversing the probes, then the circuit board is short. You should get reading one time and just 1 on the other time.

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