An audio amplifier identified by a large heat sink and large capacitors.
An audio amplifier is the final stage of amplification where the signal is raised to a level that can be fed into a headset or speaker, allowing you to get the benefit of the signal, be it music or voice reproduction. The greatest amount of power consumption is required here. The audio amplifier is typically easy to troubleshoot, as it often provides visible clues as to what happened.
Instructions
1. Unplug the amplifier from the wall. Using a screwdriver, remove the screws holding the top cover and look inside looking for a burned component such as a resistor or power transistor. Smell the inside of the amplifier to see if you can detect a burned odor.
2. Plug in the amplifier and, using the service manual, locate the power transistors. Check with a multimeter to see if there is a voltage on any of the transistor pins. In some cases there will be a power-integrated circuit with several pins attached. Locate the power one and check for a voltage.
3. Check to make sure the fuse in the back hasn't blown. A blown fuse needs to be replaced. No voltage indicates a faulty power supply, and repair to this section is best done by an experienced service technician.
4. Confirm the power supply is working, the speakers are all right and there is a signal going into the amplifier. Then, using a can of freeze, spray the components one at a time with a short burst, freezing the components starting with the power transistors or power IC, then the capacitors in the same area.
5. The last component frozen before the amplifier starts to work is likely to be the faulty one. Unplug the power supply and use needle-nose pliers to pull one pin at a time out of the board after heating it to melt the solder. Use a solder wick and clean the holes left on the board. Remove the screws holding the circuit board down and lift the board to gain access to the under side.
6. Identify the faulty component using the service manual and replace it with a new component in the same position. Insert the component pins into the holes, making sure not to bend the pins. Solder them in place, taking care not to short the pins together by using excess solder. Clip off the excess pins protruding from the under side of the board using a side cutter.
7. Secure the circuit board back in place, plug the amplifier in and turn on. With the amplifier working, turn it off and replace the cover.
Tags: audio amplifier, power supply, circuit board, power transistors, screws holding, service manual
