The Behringer B300 is an active two-way loudspeaker system with two-band equalisation, a built-in microphone preamplifier and a total of 300 watts of power, designed mostly for rehearsal halls and small, club-type venues. Although serious repairs on B300 speakers should be left to a qualified technician, there are some things that consumers with basic electronics knowledge can do to fix common problems associated with speakers of this type to keep them working well. Doing small repairs can also save you quite a bit of money if you're a musician on a budget.
Unplug the power cable from the wall or surge protector and inspect it for frayed edges, burnt contacts and general signs of wear. A damaged power cable is often responsible for intermittent power failure, no power at all or a weak audio signal.
Test the contacts of the power cable with a multimeter for continuity. You can find a basic multimeter at most hardware stores, electronics supply shops and through many different online retailers. All multimeters have different operating instructions. Read the instructions that came with yours if you are unsure of how to test a power cable.
Replace the cable with a working cable if you find frayed edges or any signs of damage. If the cable does not test properly, discard it immediately. It could cause damage to internal components if you continue to use it.
Test the contacts on the back of the speaker with your multimeter. Again, this is a specific task, and you need to know how to check the readings on your particular multimeter.
Unscrew the plug connection on the back of the speaker. Unsolder the cabling connected to the plug, making a note of what cables were connected where.
Replace the plug connection with one of the same type. Various connectors can be purchased or ordered through an electronics supply store in person or online. If you are unsure of the type of connector, take the item with you.
Solder the new power cable in place. Plug the speaker in and test it to make sure you have fixed the problem. Note any fluctuations in power or odd clicking-type sounds. This may be the sign of a more serious internal power problem. Seek help from a qualified technician.
Never work on a speaker if you are unsure of what you are doing. You may damage the speaker, turning a potentially small problem into a larger, more expensive problem down the road.