Mackie 406M Owner's Manual - Page 28

The bass frequencies diminish when standing center, but get louder as you approach one side! • Check the polarity of the speaker cable connections. You may have your positive and negative connections reversed at one end of one speaker cable. As soon as the music gets loud, the mixer shuts down! • Check the LEVEL meters. Be sure that the CLIP LED is not lighting up frequently or continuously. • Make sure there is room behind the powered mixer to provide sufficient ventilation to the heatsink. If it gets too hot, it will shut down the show. • Is the total speaker impedance connected to each amplifier 2 ohms or greater? If the impedance is too low, the amplifier may overheat and shut down. It hurts when I touch my arm, or my leg, or even my head! • You have a broken finger. Bad sound! • Is it loud and distorted? Follow the procedures described in the "Quick Start" section to verify that the levels are set properly. • Is the input connector plugged completely into the jack? Check the speaker connections and verify that all connections are tight and that there are no stray strands of wire shorting across the speaker terminals. • Keep practicing. Noise/Hum • Turn the channel VOLUME knobs down one by one. If the noise disappears, it's either that channel or whatever is plugged into it. If not, turn down the EFX TO MAIN control. If the noise disappears, it could be coming from an external effects device plugged into the EFFECTS RETURN jack(s). • Make sure all connections to the powered mixer 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 SCRbased device on the same AC circuit as the powered mixer? Use an AC line filter or plug the powered mixer into a different AC circuit. • Is there an external processor or other electronic device connected to the powered mixer? Make sure it is plugged into the same AC circuit as the powered mixer to reduce the possibility of creating a ground loop. • Refer to "Grounding" in Appendix B. There's sound in the monitors even though all the channel MONitor controls are turned down! • Make sure the EFX TO MON control is turned down. This control adds the "wet" effects signal to the monitor output even when there is no monitor signal present. Repair Service for the PPM Series Powered Mixers is available only from one of our authorized domestic service stations or at the factory, located in sunny Woodinville, Washington. Service for Mackie Powered Mixers living outside the United States can be obtained through local dealers or distributors. If your powered mixer needs service, follow these instructions: 1. Review the preceding troubleshooting suggestions. Please. 2. Call Tech Support at 1-800-258-6883, 8am to 5pm PST, to explain the problem and request an RA (Return Authorization) number. Have your powered mixer's serial number ready. You must have an RA number before you can obtain service at the factory or an authorized service center. 3. Keep this owner's manual. We don't need it to repair the powered mixer. 4. Pack the powered mixer in its original package, including endcaps and box. This is very important. When you call for the RA number, please let Tech Support know if you need new packaging. Mackie is not responsible for any damage that occurs due to non-factory packaging. 5. Include a legible note stating your name, shipping address (no P.O. boxes), daytime phone number, RA number, and a detailed description of the problem, including how we can duplicate it. 28