Mackie DLM12S Owner's Manual - Page 15

Owner's Manual Appendix A: Service Information If you think your Mackie product has a problem, please check out the following troubleshooting tips and do your best to confirm the problem. Visit the Support section of our website (www.mackie.com/support) where you will find lots of useful information such as FAQs and other documentation. You may find the answer to the problem without having to send your Mackie product away. Troubleshooting Poor bass performance • Check the polarity of the connections between the mixer and the subwoofers. You may have your positive and negative connections reversed at one end of one cable, causing one subwoofer to be out-of-phase with the other. • Poor bass performance may be the result of bad AC power. See the section titled 'AC Power' on the previous page for further details. No power Poor sound • Our favorite question: Is it plugged in? Make sure the AC outlet is live [check with a tester or lamp]. • Our next favorite question: Is the power switch on? If not, try turning it on. • Make sure the line cord is securely seated in the line cord socket and plugged all the way into the AC outlet. • Is it loud and distorted? Make sure that you're not overdriving a stage in the signal chain. Verify that all level controls are set properly. • Is the input connector plugged completely into the jack? Be sure all connections are secure. Noise • Is the power LED on the front panel glowing green? If not, make sure the AC outlet is live. If so, refer to "No sound" below. • The internal AC line fuse may be blown. This is not a user serviceable part. If you suspect the AC line fuse is blown, please see the "Repair" section next. No sound • Is the input level control for the input source turned all the way down? Verify that all the volume controls in the system are properly adjusted. Look at the level meter to ensure that the mixer is receiving a signal. • Is the signal source working? Make sure the connecting cables are in good repair and securely connected at both ends. Make sure the output volume (gain) control on the mixing console is turned up sufficiently to drive the inputs of the speaker. • Make sure all connections to the active subwoofers are good and sound. • Make sure none of the signal cables are routed near AC cables, power transformers, or other EMI-inducing devices. • Is there a light dimmer or other SCR-based device on the same AC circuit as the DLM12S? Use an AC line filter or plug the subwoofer into a different AC circuit. Hum • Try disconnecting the cable connected to the input jack. If the noise disappears, it could be a "ground loop," rather than a problem with the DLM12S subwoofer. Try some of the following troubleshooting ideas: • Use balanced connections throughout your system for the best noise rejection. • Make sure the mixer does not have a mute on or a processor loop engaged. If you find something like this, make sure the volume/gain is turned down before disengaging the offending switch. • Whenever possible, plug all the audio equipment's line cords into outlets which share a common ground. The distance between the outlets and the common ground should be as short as possible. • Has it shut down? Make sure there is at least six inches of free space behind each DLM subwoofer. Owner's Manual 15