If the microphone is dynamic, first check the position of the switch. Then disconnect the microphone from the socket, and then connect the plug to an ohmmeter. In the switch position the resistance of the voice coil should be several tens of Ohms, and is disabled it should be the switch is shorted. Finding open, the bell separately the cable and voice coil, and find a short, check the switch and also the cable.
Dynamic microphone with plug type DIN may not work if the plug is soldered under the old standard, and the nest - according to the new, or Vice versa. A shared contact in that Jack is always average, but the signal can be both right and left. If necessary, perform the soldering in the plug.
Electret microphone switch has not. Test should be only a digital device, analog because you can burn a field-effect transistor built into the microphone capsule. The resistance between the contacts of the plug should be from 500 to 5000 Ohms, and it can vary depending on the polarity of the probes. If there is an open or short, proceed as described above. If the microphone capsule will have to change the polarity. In the repair of all microphones as dynamic and electret cannot be made perepiski when the plug is inserted in the slot.
The condition of the microphone may not work if the VCR is set to the zero position of the level control recording and karaoke system - you can adjust the sensitivity. Check their position and adjust as necessary. Also the sound can be very quiet if the device is designed for an electret microphone connect a dynamic. The same result is possible by connecting a 3-volt electret microphone inset to a device designed for a 1.5-volt. If the device is designed for dynamic microphone, electret with him will not work at all.
When unhealthy good microphone connected to your computer, first check the settings of the software mixer. Note that mixers of one OS tick can mean the enabled state of the corresponding input, and the other is disabled. In the case that the manipulation of the mixer will not lead to success, check whether the socket is inserted a microphone plug (it should be green). If not helped by it, make sure sound card is working and properly configured.