User manual CLARION APX 400.4

[. . . ] Protection circuits safeguard the amplifier when overheating and speaker shorts or improper load conditions occur. All connections and controls of the APX200. 2 and APX400. 2 are on the end panels and are easy to understand. We use gold-plated RCA and barrier connectors to ensure the best electrical connection for your system. Included is an external automotive type fuse that is easy to replace. [. . . ] MOUNTING PRECAUTIONS Although the Clarion APX200. 2 and APX400. 2 both incorporate heat sinks and protection circuits, mounting the amplifier in a tight space without any air movement can still damage internal circuitry over time. Choose a site that provides adequate ventilation around the amplifier. For easy system set-up, mount the amplifier so the front panel controls will be accessible after installation. In addition, observe the following precautions: 1. For the most efficient cooling, mount the amplifier so cool air runs along the length of the fins rather than across them. Remember, any moving air will dissipate heat. Avoid mounting to subwoofer enclosures or areas prone to vibration. Do not install the amplifier on plastic or other combustible materials. Prior to drilling, make sure proposed mounting holes will not cut into the fuel tank, fuel lines, brake lines (under chassis) or electrical wiring. WIRING PRECAUTIONS Read all wiring precautions. If you are not sure of the connections, contact your authorized Clarion dealer. Before installation, make sure the source unit Power switch is in the OFF position. Disconnect the negative (-) lead of the battery before making any power connections. When making connections, be sure that each connection is clean and secure. Insulate final connections with electrical tape or shrink tubing. Failure to do so may damage your equipment. 9 4. A secure clean ground connection is critical to the performance of your Clarion amplifier. Use the shortest ground wire possible snd securely connect to the car chassis to minimize resistance and avoid noise problems. Add an external fuse on the amplifier's positive (+) power lead and connect it as close as possible to the vehicle's (+) battery terminal. Use a rating that equals the total current consumption at full output of all amplifiers in the system. Adding an external fuse will protect the electrical system from short circuits that can cause a fire. Refer to Figure 6 when making electrical connections. [. . . ] Check polarity of wires from amplifier to each speaker as defined by the system design. Solution Incorrect wiring or short circuit. Review Installation and check all wiring connections. Problem Whining or ticking noise in the audio with engine on. [. . . ]