SONY KV HA21M50 _ KV HA21M80 _ KV HA21M81 _ KV HA21M80/H _ KV HA21M83 _ KV HA21P52 _ KV HA14M80

Fault:  No sound or distorted and low sound output from the speaker.

  Before do any thing, just check the settings first.  If sound MUTE is ON, there will be no sound from the output section.  Be sure it is in OFF state.

  The second step is to check whether you get audio signals.  To check this, plug-in a good headphone to the headphone socket.  If you do get sound by headphone, and not from the loudspeaker, make sure that the headphone socket has some trouble with its internal switchover contacts.  Just push in and take out the headphone pin into the headphone socket for at least five times, and check you get sound from the loudspeaker.

  If not, check the loud speakers for voice coil trouble.  You can check this without the help of a multimeter.  Take a good torch cell, and connect its two pole with two pieces of wire, and touch these wires to the terminals of the loud speaker.  If the speaker is good, you will hear a ‘Thumb’ sound for each intermittent touch with wires on the speakers’ connection tabs. If no sound is heard, be sure that the speaker I damaged, and should be replaced with same type.  Speakers’ impedance will be marked on its magnet.

If the speaker is found good, and there is no sound from it, even though you get sound output by connecting the headphones to its headphone socket, make sure that the headphone socket is faulty.  To replace it you have to disconnect it from the circuit, and buy a new one of same type.  It is a semiskilled work indeed.

If you can’t get any sound output from the headphone socket by connecting a good headphone to it, either the audio output IC do not get proper voltage, or may be defective.

  Audio output IC used with this set is [IC203] [AN 5276].  It is a dual amplifier type, that is, a single IC is used to amplify both stereo channel signals.  Even one channel amplifier stage inside this IC is defective; you have to replace the IC.

  It is a 12 solder terminal IC.  Check all the terminal soldering of this IC for loose solder points.  It is best to resolder all these solder terminals, by applying a little more solder, without making any solder short in between adjacent solder terminals.  Check the input voltage at [pin number 10] of this IC. If voltage is there, and even reordering terminals does not help you, replace the IC.  It is defective.