Testing of Mobile Phone Microphone or Mouthpiece

Mobile phone microphone also known as mouthpiece is the one that intercepts the voice to transmit to other  mobile phone users. Without it or a defective one will result that the other user on a phone cannot hear the one with a defective microphone on its mobile phone handsets.
A microphone is made of an electrical magnetic wire shaped into a round coil with a magnet metal surrounds it,  the mechanical vibration  generated by it will then produce an electrical voltage signal.
Checking the microphone is also been so easy, Just set the analog or digital multimeter to resistance scale then attach both test probe to its terminal. A good sign of a working microphone tends to have a reading of about 1000 ohms and by changing the probe on mic terminal it shows open or 1 in digital multimeter.

Testing of Mobile Phone Battery Voltage

 

A  working battery voltage is approx. 3.7 volts DC,  below this voltage range the phone will not be power on. Checking the battery voltage by a digital multi-meter is so easy, just set  it to a DC range 20 volts then attach the both test probes to each corresponding polarity, Red probe to positive terminal, then black probe to negative battery terminal. Check the maximum battery voltage reading  3.7 volts. A battery voltage lower than 3.7 volts can power on the handsets but it shows Battery Low on a screen. A battery voltage lower than 2 to zero volts will hardly charge the phone and won't power up the phone.